Trilaciclib

• Molecular FormulaC₂₄H₃₀N₈O
• Average mass446.548 Da
• G1T 28

PATENT, WO 2014144326, Compound 89 (also referred to as Compound T)

WO2014144847A3
Inventors	Norman E. Sharpless, Jay Copeland Strum, John Emerson Bisi, Patrick Joseph Roberts, Francis Xavier Tavares
Applicant	G1 Therapeutics, Inc.

Norman Sharpless
Born	Norman Edward Sharpless September 20, 1966 (age 51) Greensboro, North Carolina
Nationality	American
Other names	Ned Sharpless
Occupation	Director, Lineberger Comprehensive Cancer Center Founder, G1 Therapeutics ($GTHX)
Notable work	Wellcome Distinguished Professor, American Society of Clinical Investigation Member, Association of American Cancer Institute board of directors,

NCI Director Dr. Norman E. Sharpless

Synthesis

WO  2016040858

 

Trilaciclib (G1T28)

Trilaciclib is a potential first-in-class short-acting CDK4/6 inhibitor in development to preserve hematopoietic stem cells and enhance immune system function during chemotherapy. Trilaciclib is administered intravenously prior to chemotherapy and has the potential to significantly improve treatment outcomes.

G1 is currently evaluating trilaciclib in four Phase 2 clinical trials: three studies in patients with small-cell lung cancer (SCLC), and one study in patients with triple-negative breast cancer (TNBC). Preliminary data from the SCLC trials were presented at the American Society of Clinical Oncology 2017 Annual Meeting and at the 2016 World Conference on Lung Cancer.

Data from a Phase 1 trial in healthy volunteers were presented at the American Society of Clinical Oncology 2015 Annual Meeting and published in Science Translational Medicine. Trilacicilib has been extensively studied in animals; these preclinical data have been presented at several scientific meetings and published in Molecular Cancer Therapeutics, Science Translational Medicine, and Cancer Discovery.

Trilaciclib is a small molecule, competitive inhibitor of cyclin dependent kinases 4 and 6 (CDK4/6), with potential antineoplastic and chemoprotective activities. Upon intravenous administration, trilaciclib binds to and inhibits the activity of CDK4/6, thereby blocking the phosphorylation of the retinoblastoma protein (Rb) in early G1. This prevents G1/S phase transition, causes cell cycle arrest in the G1 phase, induces apoptosis, and inhibits the proliferation of CDK4/6-overexpressing tumor cells. In patients with CDK4/6-independent tumor cells, G1T28 may protect against multi-lineage chemotherapy-induced myelosuppression (CIM) by transiently and reversibly inducing G1 cell cycle arrest in hematopoietic stem and progenitor cells (HSPCs) and preventing transition to the S phase. This protects all hematopoietic lineages, including red blood cells, platelets, neutrophils and lymphocytes, from the DNA-damaging effects of certain chemotherapeutics and preserves the function of the bone marrow and the immune system. CDKs are serine/threonine kinases involved in the regulation of the cell cycle and may be overexpressed in certain cancer cell types. HSPCs are dependent upon CDK4/6 for proliferation.

Trilaciclib (G1T28) is a CDK4/6 inhibitor in phase II clinical development as a chemoprotectant at G1 Therapeutics for first- or second-line treatment in patients with metastatic triple negative breast cancer, in combination with gemcitabine and carboplatin. Also, phase II trials are ongoing in newly diagnosed, treatment-naive small-cell lung cancer patients, in combination with carboplatin, etoposide, and atezolizumab and phase I trials in previously treated small-cell lung cancer patients, in combination with topotecan.

U.S. Patent Nos. 8,822,683; 8,598,197; 8,598,186, 8,691,830, 8,829,102, 8,822,683, 9, 102,682, 9,499,564, 9,481,591, and 9,260,442, filed by Tavares and Strum and assigned to Gl Therapeutics describe a class of N-(heteroaryl)-pyrrolo[3,2-d]pyrimidin-2-amine cyclin dependent kinase inhibitors including those of the formula with variables as defined therein):

U.S. Patent Nos. 9,464,092, 9,487,530, and 9,527,857 which are also assigned to Gl Therapeutics describe the use of the above pyrimidine-based agents in the treatment of cancer.

These patents provide a general synthesis of the compounds that is based on a coupling reaction of a fused chloropyrimidine with a heteroaryl amine to form the central disubstituted amine. Such coupling reactions are sometimes referred to as Buchwald coupling (see WO Ί56 paragraph 127; reference WO 2010/020675). The lactam of the fused chloropyrimidine, for example, a 2-chloro-spirocyclo-pyrrolo[2,3-d]pyrimidine-one such as Intermediate K as shown below can be prepared by dehydration of the corresponding carboxylic acid. The reported process to prepare intermediate IK requires seven steps.

(Intermediate IK; page 60, paragraph 215 of WO Ί56)

WO 2013/148748 (U.S. S.N. 61/617,657) entitled “Lactam Kinase Inhibitors” filed by Tavares, and also assigned to Gl Therapeutics likewise describes the synthesis of N-(heteroaryl)-pyrrolo[3,2-d]pyrimidin-2-amines via the coupling reaction of a fused chloropyrimidine with a heteroaryl amine to form the central disubstituted amine.

WO 2013/163239 (U.S. S.N. 61/638,491) “Synthesis of Lactams” describes a method for the synthesis of this class of compounds with the variation that in the lactam preparation step, a carboxylic acid can be cyclized with a protected amine in the presence of a strong acid and a dehydrating agent, which can be together in one moiety as a strong acid anhydride. The purported improvement is that cyclization can occur without losing the protecting group on the amine before cyclization. The typical leaving group is “tBOC” (t-butoxycarbonyl). The application teaches (page 2 of WO 2013/163239) that the strong acid is, for example, trifluoroacetic acid anhydride, tribromoacetic acid anhydride, trichloroacetic acid anhydride or mixed anhydrides. An additional step may be necessary to take off the N-protecting group. The dehydrating agent can be a carbodiimide-based compound such as DCC (Ν,Ν-dicyclohexylcarbodiimide), EDC (l-ethyl-3-(3-dimethylaminopropyl)carbodiimide, or DIC (Ν,Ν-diisopropylcarbodiimide). DCC and DIC are in the same class of reagents-carbodiimides. DIC is sometimes considered better because it is a liquid at room temperature, which facilitates reactions.

WO 2015/061407 filed by Tavares and licensed to Gl Therapeutics also describes the synthesis of these compounds via the coupling of a fused chloropyrimidine with a heteroaryl amine to form the central disubstituted amine. WO ‘407 focuses on the lactam production step and in particular describes that the fused lactams of these compounds can be prepared by treating the carboxylic acid with an acid and a dehydrating agent in a manner that a leaving group on the amine is not removed during the amide-forming ring closing step.

Other publications that describe compounds of this general class include the following. WO 2014/144326 filed by Strum et al. and assigned to Gl Therapeutics describes compounds and methods for protection of normal cells during chemotherapy using pyrimidine based CDK4/6 inhibitors. WO 2014/144596 filed by Strum et al. and assigned to Gl Therapeutics describes compounds and methods for protection of hematopoietic stem and progenitor cells against ionizing radiation using pyrimidine based CDK4/6 inhibitors. WO 2014/144847 filed by Strum et al. and assigned to Gl Therapeutics describes HSPC-sparing treatments of abnormal cellular proliferation using pyrimidine based CDK4/6 inhibitors. WO2014/144740 filed by Strum et al. and assigned to Gl Therapeutics describes highly active anti -neoplastic and anti-proliferative pyrimidine based CDK 4/6 inhibitors. WO 2015/161285 filed by Strum et al. and assigned to Gl Therapeutics describes tricyclic pyrimidine based CDK inhibitors for use in radioprotection. WO 2015/161287 filed by Strum et al. and assigned to Gl Therapeutics describes analogous tricyclic pyrimidine based CDK inhibitors for the protection of cells during chemotherapy. WO 2015/161283 filed by Strum et al. and assigned to Gl Therapeutics describes analogous tricyclic pyrimidine based CDK inhibitors for use in HSPC-sparing treatments of RB-positive abnormal cellular proliferation. WO 2015/161288 filed by Strum et al. and assigned to Gl Therapeutics describes analogous tricyclic pyrimidine based CDK inhibitors for use as anti -neoplastic and anti-proliferative agents. WO 2016/040858 filed by Strum et al. and assigned to Gl Therapeutics describes the use of combinations of pyrimidine based CDK4/6 inhibitors with other anti-neoplastic agents. WO 2016/040848 filed by Strum et al. and assigned to Gl Therapeutics describes compounds and methods for treating certain Rb-negative cancers with CDK4/6 inhibitors and topoisomerase inhibitors.

Other biologically active fused spirolactams and their syntheses are described, for example, in the following publications. Griffith, D. A., et al. (2013). “Spirolactam-Based Acetyl-CoA Carboxylase Inhibitors: Toward Improved Metabolic Stability of a Chromanone Lead Structure.” Journal of Medicinal Chemistry 56(17): 7110-7119, describes metabolically stable spirolactams wherein the lactam resides on the fused ring for the inhibition of acetyl-CoA carboxylase. WO 2013/169574 filed by Bell et al. describes aliphatic spirolactams as CGRP receptor antagonists wherein the lactam resides on the spiro ring. WO 2007/061677 filed by Bell et al. describes aryl spirolactams as CGRP receptor antagonists wherein the lactam resides on the spiro ring. WO 2008/073251 filed by Bell et al. describes constrained spirolactam compounds wherein the lactam resides on the spiro ring as CGRP receptor antagonists. WO 2006/031606 filed by Bell et al. describes carboxamide spirolactam compounds wherein the spirolactam resides on the spiro ring as CGRP receptor antagonists. WO 2006/031610, WO 2006/031491, and WO 2006/029153 filed by Bell et al. describe anilide spirolactam compounds wherein the spirolactam resides on the spiro ring; WO 2008/109464 filed by Bhunai et al. describes spirolactam compounds wherein the lactam resides on the spiro ring which is optionally further fused.

Given the therapeutic activity of selected N-(heteroaryl)-pyrrolo[3,2-d]pyrimidin-2-amines, it would be useful to have additional methods for their preparation. It would also be useful to have new intermediates that can be used to prepare this class of compounds.

PATENT

WO 2014144596

PATENT

WO 2014144326

Compound 89 (also referred to as Compound T)

WO2014144847A3
Inventors	Norman E. Sharpless, Jay Copeland Strum, John Emerson Bisi, Patrick Joseph Roberts, Francis Xavier Tavares
Applicant	G1 Therapeutics, Inc.

EXAMPLES

Intermediates B, E, K, L, 1A, IF and 1CA were synthesized according to US 8,598,186 entitled CDK Inhibitors to Tavares, F.X. and Strum, J.C..

The patents WO 2013/148748 entitled Lactam Kinase Inhibitors to Tavares, F.X., WO 2013/163239 entitled Synthesis of Lactams to Tavares, F.X., and US 8,598,186 entitled CDK Inhibitors to Tavares, F.X. and Strum, J.C. are incorporated by reference herein in their entirety. Example 1

Synthesis of tert-butyl N- [2- [(5-bromo-2-chloro-pyrimidin-4yl)amino] ethyl] carbamate, Compound 1

To a solution of 5-bromo-2,4-dichloropyrimidine (3.2 g, 0.0135 mol) in ethanol (80 mL) was added Hunig’s base (3.0 mL) followed by the addition of a solution of N-(tert- butoxycarbonyl)-l,2-diaminoethane (2.5 g, 0.0156 mole) in ethanol (20 mL). The contents were stirred overnight for 20 hrs. The solvent was evaporated under vacuum. Ethyl acetate (200 mL) and water (100 mL) were added and the layers separated. The organic layer was dried with magnesium sulfate and then concentrated under vacuum. Column chromatography on silica gel using hexane/ethyl acetate (0- 60%) afforded tert-butyl N-[2-[(5-bromo-2-chloro-pyrimidin-4- yl)amino]ethyl]carbamate. ¹HNMR (d6-DMSO) δ ppm 8.21 (s, 1H), 7.62 (brs, 1H), 7.27 (brs, 1H), 3.39 (m, 2H), 3.12 (m, 2H), 1.34 (s, 9H). LCMS (ESI) 351 (M + H).

Example 2

Synthesis of tert-butyl N-[2-[[2-chloro-5-(3,3-diethoxyprop-l-ynyl)pyrimidin-4- yl] amino] ethyl] carbamate, Compound 2

To tert-butyl N-[2-[(5-bromo-2-chloro-pyrimidin-4-yl)amino]ethyl]carbamate (1.265 g, 6 mmol) in THF (10 mL) was added the acetal (0.778 mL, 5.43 mmol), Pd(dppf)CH₂Cl₂ (148 g), and triethylamine (0.757 mL, 5.43 mmol). The contents were degassed and then purged with nitrogen. To this was then added Cul (29 mg). The reaction mixture was heated at reflux for 48 hrs. After cooling, the contents were filtered over CELITE™ and concentrated. Column chromatography of the resulting residue using hexane/ethyl acetate (0- 30%) afforded tert-butyl N- [2- [ [2-chloro-5 -(3 ,3 -diethoxyprop- 1 -ynyl)pyrimidin-4-yl]amino] ethyl] carbamate. ¹HNMR (d6-DMSO) δ ppm 8.18 (s, 1H), 7.63 (brs, 1H), 7.40 (brs, 1H), 5.55 (s, 1H), 3.70 (m, 2H), 3.60 (m, 2H), 3.42 (m, 2H), 3.15 (m, 2H), 1.19 – 1.16 (m, 15H). LCMS (ESI) 399 (M + H).

Example 3

Synthesis of tert-butyl N-[2-[2-chloro-6-(diethoxymethyl)pyrrolo[2,3-d]pyrimidin-7- yl] ethyl] carbamate, Compound 3

To a solution of the coupled product (2.1 g, 0.00526 mole) in THF (30 mL) was added TBAF solid (7.0 g). The contents were heated to and maintained at 65 degrees for 2 hrs. Concentration followed by column chromatography using ethyl acetate/hexane (0-50%) afforded tert-butyl N-[2-[2-chloro-6-(diethoxymethyl)pyrrolo[2,3-d]pyrimidin-7-yl]ethyl]carbamate as a pale brown liquid (1.1 g). ¹FiNMR (d6-DMSO) δ ppm 8.88 (s, 1H), 6.95 (brs, 1H), 6.69 (s, 1H), 5.79 (s, 1H), 4.29 (m, 2H), 3.59 (m, 4H), 3.34 (m, 1H), 3.18 (m, 1H), 1.19 (m, 9H), 1.17 (m, 6H). LCMS (ESI) 399 (M + H).

Example 4

Synthesis of tert-buty\ N-[2-(2-chloro-6-formyl-pyrrolo [2,3-d] pyrimidin-7- yl)ethyl] carbamate, Compound 4

To the acetal (900 mg) from the preceeding step was added AcOH (8.0 mL) and water

(1.0 mL). The reaction was stirred at room temperature for 16 hrs. Cone, and column chromatography over silica gel using ethyl acetate/hexanes (0- 60%) afforded tert-butyl N-[2-(2- chloro-6-formyl-pyrrolo[2,3-d]pyrimidin-7-yl)ethyl]carbamate as a foam (0.510 g). ¹HNMR (d6-DMSO) δ ppm 9.98 (s, 1H), 9.18 (s, 1H), 7.66 (s, 1H), 6.80 (brs, 1H), 4.52 (m, 2H), 4.36 (m, 2H), 1.14 (s, 9H). LCMS (ESI) 325 (M + H).

Example 5

Synthesis of 7- [2-(teri-butoxycarbonylamino)ethyl] -2-chloro-pyrrolo [2,3-d] pyrimidine-6- carboxylic acid, Compound 5

To the aldehyde (0.940 g) from the preceeding step in DMF (4 mL) was added oxone (1.95 g, 1.1 eq). The contents were stirred at room temp for 7 hrs. Silica gel column chromatography using hexane/ethyl acetate (0- 100%) afforded l-\2-(tert- butoxycarbonylamino)ethyl]-2-chloro-pyrrolo[2,3-d]pyrimidine-6-carboxylic acid (0.545 g). ¹HNMR (d6-DMSO) δ ppm 9.11 (s, 1H), 7.39 (s, 1H), 4.38 (m, 2H), 4.15 (m, 2H), 1.48 (m, 9H). LCMS (ESI) 341(M + H).

Example 6

Synthesis of methyl 7-[2-(teri-butoxycarbonylamino)ethyl]-2-chloro-pyrrolo[2,3- d]pyrimidine-6-carboxylate, Compound 6

To a solution of 2-chloro-7-propyl-pyrrolo[2,3-d]pyrimidine-6-carboxylic acid (0.545 g, 0.00156 mole) from the preceeding step in toluene (3.5 mL) and MeOH (1 mL) was added TMS- diazomethane (1.2 mL). After stirring overnight at room temperature, the excess of TMS- diazomethane was quenched with acetic acid (3 mL) and the reaction was concentrated under vacuum. The residue was purified by silica gel column chromatography with hexane/ethyl acetate (0- 70%) to afford methyl 7-[2-(tert-butoxycarbonylamino)ethyl]-2-chloro-pyrrolo[2,3- d]pyrimidine-6-carboxylate as an off white solid (0.52 g). ¹HNMR (d6-DMSO) δ ppm 9.10 (s, 1H), 7.45 (s, 1H), 6.81 (brs, 1H) 4.60 (m, 2H), 3.91 (s, 3H), 3.29 (m, 2H), 1.18 (m, 9H) LCMS (ESI) 355 (M + H).

Example 7

Synthesis of Chloro tricyclic amide, Compound 7

To methyl 7- [2-(tert-butoxycarbonylamino)ethyl] -2-chloro-pyrrolo [2,3 -d]pyrimidine-6- carboxylate (0.50 g, 0.0014 mole) from the preceeding step in dichloromethane (2.0 mL) was added TFA (0.830 mL). The contents were stirred at room temperature for 1 hr. Concentration under vacuum afforded the crude amino ester which was suspended in toluene (5 mL) and Hunig’s base (0.5 mL). The contents were heated at reflux for 2 hrs. Concentration followed by silica gel column chromatography using hexane/ethyl acetate (0- 50%) afforded the desired chloro tricyclic amide (0.260 g). ¹HNMR (d6-DMSO) δ ppm 9.08 (s, 1H), 8.48 (brs, 1H), 7.21 (s, 1H) 4.33 (m, 2H), 3.64 (m, 2H). LCMS (ESI) 223 (M + H).

Example 8

Synthesis of chloro-N-methyltricyclic amide, Compound 8

To a solution of the chloro tricycliclactam, Compound 7, (185 mg, 0.00083 mole) in DMF (2.0 mL) was added sodium hydride (55% dispersion in oil, 52 mg). After stirring for 15 mins, methyl iodide (62 μί, 1.2 eq). The contents were stirred at room temperature for 30 mins. After the addition of methanol (5 mL), sat NaHCOs was added followed by the addition of ethyl acetate. Separation of the organic layer followed by drying with magnesium sulfate and concentration under vacuum afforded the N-methylated amide in quantitative yield. ¹FiNMR (d6-DMSO) δ ppm 9.05 (s, 1H), 7.17 (s, 1H) 4.38 (m, 2H), 3.80 (m, 2H), 3.05 (s, 3H). LCMS (ESI) 237 (M + H). Example 9

Synthesis of l-methyl-4-(6-nitro-3-pyridyl)piperazine, Compound 9

To 5-bromo-2-nitropyridine (4.93 g, 24.3 mmole) in DMF (20 mL) was added N- methylpiperazine (2.96 g, 1.1 eq) followed by the addition of DIPEA (4.65 mL, 26.7 mmole). The contents were heated at 90 degrees for 24 hrs. After addition of ethyl acetate (200 mL), water (100 mL) was added and the layers separated. Drying followed by concentration afforded the crude product which was purified by silica gel column chromatography using (0-10%) DCM/Methanol. ¹HNMR (d6-DMSO) δ ppm 8.26 (s, 1H), 8.15 (1H, d, J = 9.3 Hz), 7.49 (1H, d, J = 9.4 Hz), 3.50 (m, 4H), 2.49 (m, 4H), 2.22 (s, 3H).

Example 10

Synthesis of 5-(4-methylpiperazin-l-yl)pyridin-2-amine, Compound 10

To l-methyl-4-(6-nitro-3-pyridyl)piperazine (3.4 g) in ethyl acetate (100 mL) and ethanol (100 mL) was added 10%> Pd/C (400 mg) and then the reaction was stirred under hydrogen (10 psi) overnight. After filtration through CELITE™, the solvents were evaporated and the crude product was purified by silica gel column chromatography using DCM/ 7N ammonia in MeOH (0- 5%) to afford 5-(4-methylpiperazin-l-yl)pyridin-2-amine (2.2 g). ¹HNMR (d6-DMSO) δ ppm 7.56 (1H, d, J = 3 Hz), 7.13 (1H, m), 6.36 (1H, d, J = 8.8 Hz), 5.33 (brs, 2H), 2.88 (m, 4H), 2.47 (m, 4H), 2.16 (s, 3H).

Example 11

Synthesis of tert-butyl 4-(6-amino-3-pyridyl)piperazine-l-carboxylate, Compound 11

This compound was prepared as described in WO 2010/020675 Al .

Synthesis of Compound 89 (also referred to as Compound T)

Compound 89 was synthesized in a similar manner to that described for compound 78 and was converted to an HCl salt. ¹HNMR (600 MHz, DMSO-d₆) δ ppm 1.47 (br. s., 6 H) 1.72 (br. s., 2 H) 1.92 (br. s., 2 H) 2.77 (br. s., 3 H) 3.18 (br. s., 2 H) 3.46 (br. s., 2 H) 3.63 (br. s., 2 H) 3.66 (d, J=6.15 Hz, 2 H) 3.80 (br. s., 2 H) 7.25 (s, 1 H) 7.63 (br. s., 2 H) 7.94 (br. s., 1 H) 8.10 (br. s., 1 H) 8.39 (br. s., 1 H) 9.08 (br. s., 1 H) 11.59 (br. s., 1 H). LCMS (ESI) 447 (M + H)

PATENT

WO 2014144740

PATENT

WO 2016040858

Preparation of Active Compounds

Syntheses

The disclosed compounds can be made by the following general schemes:

Scheme 1

In Scheme 1, Ref-1 is WO 2010/020675 Al; Ref-2 is White, J. D.; et al. J. Org. Chem. 1995, 60, 3600; and Ref-3 Presser, A. and Hufher, A. Monatshefte fir Chemie 2004, 135, 1015.

Scheme 2

In Scheme 2, Ref-1 is WO 2010/020675 Al; Ref-4 is WO 2005/040166 Al; and Ref-5 is Schoenauer, K and Zbiral, E. Tetrahedron Letters 1983, 24, 573.

92

93 

3) Pd/C/H₂ 

Scheme 6

Scheme 7

NHfOH

Scheme 8

In Scheme 8, Ref-1 is WO 2010/020675 Al; Ref-2 is WO 2005/040166 Al; and Ref-3 is Schoenauer, K and Zbiral, E. Tetrahedron Letters 1983, 24, 573.

Alternatively, the lactam can be generated by reacting the carboxylic acid with a protected amine in the presence of a strong acid and a dehydrating agent, which can be together in one moiety as a strong acid anhydride. Examples of strong acid anhydrides include, but are not limited to, trifluoroacetic acid anhydride, tribromoacetic acid anhydride, trichloroacetic acid anhydride, or mixed anhydrides. The dehydrating agent can be a carbodiimide based compound such as but not limited to DCC (Ν,Ν-dicyclohexylcarbodiimide), EDC (l-ethyl-3-(3-

dimethylaminopropyl)carbodiimide or DIC (Ν,Ν-diisopropylcarbodiimide). An additional step may be necessary to take off the N-protecting group and the methodologies are known to those skilled in the art.

Alternatively, the halogen moiety bonded to the pyrimidine ring can be substituted with any leaving group that can be displaced by a primary amine, for example to create an intermediate for a final product such as Br, I, F, SMe, SO₂Me, SOalkyl, SO₂alkyl. See, for Exmaple PCT /US2013/037878 to Tavares.

Other amine intermediates and final amine compounds can be synthesized by those skilled in the art. It will be appreciated that the chemistry can employ reagents that comprise reactive functionalities that can be protected and de-protected and will be known to those skilled in the art at the time of the invention. See for example, Greene, T.W. and Wuts, P.G.M., Greene’s Protective Groups in Organic Synthesis, 4^th edition, John Wiley and Sons.

Scheme 9

CDK4/6 Inhibitors of the present invention can be synthesized according to the generalized Scheme 9. Specific synthesis and characterization of the Substituted 2-aminopyrmidines can be found in, for instance, WO2012/061156.

Compounds T, Q, GG, and U were prepared as above and were characterized by mass spectrometry and NMR as shown below:

Compound T

1H NMR (600 MHz, DMSO- d6) ppm 1.47 (br. s., 6 H) 1.72 (br. s., 2 H) 1.92 (br. s., 2 H) 2.77 (br. s., 3 H) 3.18 (br. s., 2 H) 3.46 (br. s., 2 H) 3.63 (br. s., 2 H) 3.66 (d, J=6.15 Hz, 2 H) 3.80 (br. s., 2 H) 7.25 (s, 1 H) 7.63 (br. s., 2 H) 7.94 (br. s., 1 H) 8.10 (br. s., 1 H) 8.39 (br. s., 1 H) 9.08 (br. s., 1 H) 11.59 (br. s., 1 H). LCMS ESI (M + H) 447.

PATENT

WO-2018005865

Synthesis of N-(heteroaryl)-pyrrolo[3,2-d]pyrimidin-2-amines. The application appears to be particularly focused on methods for the preparation of trilaciclib and an analog of it. Trilaciclib is the company’s lead CDK4/6 inhibitor presently in phase II trials against small-cell lung cancer and triple negative breast cancer. Interestingly, the company is working on a second CDK4/6 inhibitor, G1T38 , which is in a phase II trial against breast cancer.

GENERAL METHODS

The structure of starting materials, intermediates, and final products was confirmed by standard analytical techniques, including NMR spectroscopy and mass spectrometry. Unless otherwise noted, reagents and solvents were used as received from commercial suppliers. Proton nuclear magnetic resonance spectra were obtained on a Bruker AVANCE 500 at 500 MHz in DMSO-dis. HPLC analyses were performed on a Waters HPLC using the below HPLC method.

HPLC Method

Column: Atlantis T3 (150 ^χ 4.6, 3 μιη)

Column Temperature: 40°C

Flow Rate: 1 mL/min

Detection: UV @ 275 nm

Analysis Time: 36 min

Mobile Phase A: Water (with 0.1% Trifluoroacetic Acid)

Mobile Phase B : Acetonitrile (with 0.1% Trifluoroacetic Acid)

Sample preparation: dissolve PC sample, wet or dry solid (~1 mg of active compound) in acetonitrile/water (1/1) to achieve complete dissolution.

HPLC Method Gradient

Example 1. General Routes of Synthesis

Scheme 1-1 : Starting from an appropriately substituted halo pyrimidine, compounds of the present invention can be prepared. In Step 1 the appropriately substituted halo pyrimidine is subjected to l,4-diazaspiro[5.5]undecan-3-one in the presence of base and heat to afford a substituted spirolactam. In Step 2 the appropriately substituted spirolactam is protected with a group selected from R². In Step 3 the protected spirolactam is cyclized in the presence of base to afford a fused spirolactam. The fused spirolactam can be optionally oxidized to a sulfoxide or sulfone after Step 3, Step 4, Step 5, or Step 6. Oxidation prior to Step 3 results in undesired byproducts. In Step 4 the hydroxyl group of the fused spirolactam is converted to a leaving group.

In Step 5 the leaving group is dehydrated to afford a compound of Formula IV. In Step 6 the compound of Formula IV is optionally deprotected.

Scheme 1-2: Starting from an appropriately substituted halo pyrimidine compounds of the present invention can be prepared. In Step 1 the appropriately substituted halo pyrimidine is subjected to l,4-diazaspiro[5.5]undecan-3-one in the presence of base and heat to afford a substituted spirolactam. In Step 2 the appropriately substituted spirolactam is protected with a group selected from R². In Step 3 the protected spirolactam is cyclized in the presence of base to afford a fused spirolactam of Formula IV. The fused spirolactam can be optionally oxidized to a sulfoxide or sulfone after Step 3 or Step 4. Oxidation prior to Step 3 results in undesired byproducts. In Step 4 the compound of Formula IV is optionally deprotected.

Scheme 1-3 : Starting from an appropriately substituted alkyl glycinate, compounds of the present invention can be prepared. In Step 1 the appropriately substituted alkyl glycinate is subjected to cyclohexanone and TMSCN in the presence of base to afford a cyano species. In Step 2 the appropriately substituted cyanospecies is reduced and subsequently cyclized to afford a compound of Formula I.

Scheme 1-4

Scheme 1-4: Starting from an appropriately substituted l-(aminomethyl)cyclohexan-l-amine, compounds of the present invention can be prepared. In Step 1 the appropriately substituted l-(aminomethyl)cyclohexan-l -amine is reductively aminated with an aldehyde. In Step 2 the appropriately substituted cyclohexane amine is optionally deprotected (i.e.: the group selected from R² if not H is optionally replaced by H). In Step 3 the cyclohexane amine is cyclized to afford a compound of Formula I. In Step 4 the compound of Formula I is optionally protected.

1-5

Conversion

Scheme 1-5: Starting from an appropriately substituted halo pyrimidine, compounds of the present invention can be prepared. In Step 1 the appropriately substituted halo pyrimidine is subjected to l,4-diazaspiro[5.5]undecan-3-one in the presence of base and heat to afford a

substituted spirolactam. In Step 2 the protected spirolactam is cyclized in the presence of base to afford a fused spirolactam. The fused spirolactam can be optionally oxidized to a sulfoxide or sulfone after Step 2, Step 3, Step 4, or Step 5. Oxidation prior to Step 2 results in undesired byproducts. In Step 3 the hydroxyl group of the fused spirolactam is converted to a leaving group. In Step 4 the leaving group is dehydrated to afford a compound of Formula IV. In Step 5 the compound of Formula IV is optionally deprotected.

S

Scheme 1-6: Starting from an appropriately substituted halo pyrimidine compounds of the present invention can be prepared. In Step 1 the appropriately substituted halo pyrimidine is subjected to l,4-diazaspiro[5.5]undecan-3-one in the presence of base and heat to afford a substituted spirolactam. In Step 2 the protected spirolactam is cyclized in the presence of base to afford a fused spirolactam of Formula IV. The fused spirolactam can be optionally oxidized to a sulfoxide or sulfone after Step 2 or Step 3. Oxidation prior to Step 2 results in undesired byproducts. In Step 3 the compound of Formula IV is optionally deprotected.

Scheme 1-7: Starting from compound of Formula IV a CDK4/6 inhibitor can be prepared. In Step 1 a heteroaryl amine is subjected to a base and a compound of Formula IV is added slowly under chilled conditions to afford a nucleophilic substitution reaction. The compound of Formula IV can previously be prepared as described in the schemes herein.

Example 2. Representative Routes of Synthesis

Scheme 2-1

quant, yield 2 steps

isolated

70% yield 2 steps 75% yield 95% yield

isolated isolated isolated

Scheme 2-1 : An ester route is one embodiment, of the present invention. Ideally, the best synthesis scheme would afford crystalline intermediates to provide material of consistent purity without column chromatography, and high yielding steps while using safe and cost effective reagents when possible.

The first step in the ester route is a SNAr nucleophilic substitution of CI group in commercially available ester 3 using spirolactam 4. Due to low reactivity of 4, a reaction temperature of 85-95 °C was required. Because of the temperature requirements, DIPEA and dimethylacetamide were selected as the base and solvent, respectively. The reaction follows second-order kinetics and usually stalls after -85% conversion. Therefore, the reaction was typically stopped after 60 hours by first cooling it to room temperature at which point solid formation was observed. The mixture was then partitioned between MTBE and water and product was filtered with excellent purity with -53% yield of the desired product 5. The obtained

compound 5 was protected with a Boc group using Boc anhydride and DMAP as the catalyst and dichloromethane as the solvent. The intermediate 6 was obtained in a quantitative yield. Due to the semi-solid nature of compound 6, the material was taken to the next step without further purification. The Dieckmann condensation was initially performed with strong bases such as LiHMDS and tBuOK. A similar result to the aldehyde route (Scheme 2-2) was obtained: a partial deprotection of Boc group was observed that required column chromatography. However, the best results were obtained when DBU was used as base and THF as solvent. The reaction outcome was complete, clean conversion of 6 to 7. Moreover, the product crystallized from the reaction mixture upon seeding, and a quantitative yield was obtained for the two steps.

The hydroxyl group of 7 was removed via a two-step procedure. First, compound 7 was converted completely into triflate 8 using triflic anhydride and triethylamine in dichloromethane. The reaction was found to proceed well at 0°C. Due to the potential instability of the triflate intermediate, it was not isolated. It was immediately taken to the next step and reduced with triethylsilane and palladium tetrakis to afford the product 9 after ethyl acetate crystallization in -70% yield. The Boc group of 9 was removed using trifluoroacetic acid in dichloromethane to afford 10. Intermediate 10 was converted into the final sulfone 11 using Oxone™ in acetonitrile/water solvent system.

The obtained sulfone 11 was use-tested in the coupling step and was found to perform well. In conclusion, the route to sulfone 11 was developed which eliminated the use of column chromatography with good to excellent yields on all steps.

Scheme 2-2

Molecular Weight: 421 

Scheme 2-2: The first step of Scheme 2-2 consistently afforded product 13 contaminated with one major impurity found in substantial amount. Thorough evaluation of the reaction impurity profile by LC-MS and 2D MR was performed, which showed the impurity was structurally the condensation of two aldehyde 12 molecules and one molecule of lactam 4. Therefore, column chromatography was required to purify compound 13, which consistently resulted in a modest 30% yield. A solvent screen revealed that sec-butanol, amyl alcohol, dioxane, and tert-butanol can all be used in the reaction but a similar conversion was observed in each case. However, tert-butanol provided the cleanest reaction profile, so it was selected as a solvent for the reaction. Assessing the impact of varying the stoichiometric ratio of 4 and 12 on the reaction outcome was also investigated. The reaction was performed with 4 equivalents of amine 4 in an attempt to disrupt the 2: 1 aldehyde/amine composition of the impurity. The result was only a marginal increase in product 13 formation. The temperature impact on the reaction outcome was evaluated next. The coupling of aldehyde 12 and 4 was investigated at two different temperatures: 50 °C and 40 °C with 1 : 1 ratio of aldehyde/amine. Reactions were checked at 2 and 4 hours and then every 12 hours. The reaction progress was slow at 50°C and was accompanied by growth of other impurities. The reaction at 40°C was much cleaner; however the conversion was lower in the same time period. The mode of addition of the reagents was investigated as well at 80°C with a slow addition (over 6 hours) of either aldehyde 12 or amine 4 to the reaction mixture. The product distribution did not change and an about 1 to 1 ratio was observed between product and impurity when amine 4 was added slowly to the reaction mixture containing aldehyde 12 and

DIPEA at reflux. The product distribution did change when aldehyde 12 was added slowly to the mixture of amine 4 and DIPEA. However, the major product of the reaction was the undesired impurity. Other organic bases were tried as well as different ratios of DIPEA. No product was observed when potassium carbonate was used as a base. The results of the experiments are presented in Table 1 below.

Table 1

Compound 13 was successfully formed in three cases: triethylamine, 2,6-lutidine and DIPEA, with the DIPEA result being the best. The use of Boc protected spirolactam 4 had no effect on the impurity formation as well. Its utilization was speculated to be beneficial in performing the coupling step together with the following step, preparation of compound 14.

The major impurity formed during Step 1 of Scheme 2-2 is:

Chemical Formula:€₂₎Η_;Μ(¾ ₆( ₂ί>2

Molecular Weight: 527.4903

The second step (Boc protection of the free lactam) proceeded well using DMAP as a catalyst in dichloromethane at room temperature. The product 14 is a thick oil, and, therefore, cannot be purified by crystallization. The Boc protected intermediate 14 was cyclized successfully into the desired pentacyclic structure 10 upon treatment with a strong base such as LiHMDS or tBuOK. Surprisingly, the Boc group was partially removed during the reaction. The level of deprotection was independent from the internal reaction temperature and was positively correlated with excess of base used. Therefore the mixture of the desired product 10 and 10-Boc compound was treated with acid to completely deprotect Boc group. The conversion of methyl sulfide into the final sulfone 11 was carried out with Oxone™. Initially a mixture of methanol and water was used for the reaction. As the result, a partial displacement of sulfone by methoxy group was detected. The methanol was replaced with acetonitrile and the sulfone displacement was eliminated.

In summary, the ester route (Scheme 2-1) is preferred because:

1. Formation of the impurity during the first step of Scheme 2-2 was unavoidable and resulted in yields of < 35%.

2. Column purification was required to isolate intermediate 14.

3. The aldehyde starting material was not commercially available and required two synthetic steps from the corresponding ester.

Scheme 2-3 : Starting with cyclohexanone, compounds of the present invention can be prepared. In Step 1 the methyl glycinate is subjected to cyclohexanone and TMSCN in the presence of tri ethyl amine in DCM to afford 15. In Step 2 15 hydrogenated with hydrogen gas in the presence of catalytic platinum oxide and subsequently undergoes an intramolecular cyclization to afford compound 16 which is used in the schemes above.

Scheme 2-4: Starting with compound 17, compounds of the present invention can be prepared. In Step 1 compound 17 is subjected to ethyl 2-oxoacetate in the presence platinum on carbon and hydrogen gas to afford compound 18. In Step 2 compound 18 is Boc-deprotected with hydrochloric acid. In Step 3 compound 18 is cyclized to afford compound 16 which is used in the schemes above.

Scheme 2-5

11 19

Scheme 2-5: Starting from compound 11 the CDK 4/6 inhibitor 19 can be prepared. In Step 1 5-(4-methylpiperazin-l-yl)pyridin-2-amine is subjected to LiHMDS and compound 11 is added slowly under chilled conditions to afford a nucleophilic substitution reaction and compound 19. Compound 11 can be prepared as described in the schemes herein.

Scheme 2-6: Starting from compound 11 the CDK 4/6 inhibitor 20 can be prepared. In Step 1 5-(4-isopropylpiperazin-l-yl)pyridin-2-amine is subjected to LiHMDS and compound 11 is added slowly under chilled conditions to afford a nucleophilic substitution reaction and compound 20. Compound 11 can be prepared as described in the schemes herein.

Preparation of Compound 5:

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet, and reflux condenser was charged with ethyl 4-chloro-2-(methylthio)pyrimidine-5-carboxylate 3 (49.2 g, 0.21 mol, 1.00 equiv.), spirolactam 4 (39.2 g, 0.23 mol, 1.10 equiv.), DIPEA (54.7 g, 0.42 mol, 2.00 equiv.), and DMAc (147.6 mL, 3 vol). The batch was heated to 90-95 °C, and after 60 h, IPC confirmed -14% (AUC) of ethyl 4-chloro-2-(methylthio)pyrimidine-5-carboxylate remained. The batch was cooled to RT, and precipitate formation was observed. The suspension was diluted with MTBE (100 mL, 2 vol) and water (442 mL, 9 vol) and stirred for 2 h at RT. The product was isolated by vacuum filtration and washed with MTBE (49 mL, 1 vol). The solid cake was conditioned for 1 h and dried under vacuum at 40 °C for 16 h to afford compound 5 [41.0 g, 53% yield] as an off-white solid with a purity of >99% AUC. ¾ MR (CDCh): δ 8.76 (d, J = 2.0 Hz, 1H), 6.51-6.29 (br, 1H), 4.33 (q, J = 7.0 Hz, 2H), 3.78 (s, 2H), 3.58 (s, 2H), 2.92 (s, 2H), 2.53 (s, 3H), 1.63-1.37 (m, 12H). LCMS (ESI, m/z = 365.3 [M+H]).

Preparation of Compound 6:

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet was charged with 5 [41.0 g, 0.11 mol, 1.00 equiv.], Boc-anhydride (36.8 g, 0.17 mol, 1.50 equiv.), DMAP (1.37 g, 0.01 mol, 0.10 equiv.), and dichloromethane (287 mL, 7 vol). The batch was stirred for 3 h at RT. IPC confirmed no starting material remained (AUC). The batch was concentrated into a residue under reduced pressure and taken to the next step (a quantitative yield is assumed for this step). An aliquot (200 mg) was purified by column chromatography (heptanes/ethyl acetate 0 to 100%) to afford compound 6. ¹H MR (CDCh): δ 8.64 (s, 1H), 4.31 (q, J = 7.0 Hz, 2H), 4.07 (s, 2H), 3.83 (S, 2H), 3.15 (m, 2H), 2.56 (s, 3H), 172 (m, 3H), 1.59 (m, 15H), 1.42 (t, J= 7.0 Hz, 3H). LCMS (ESI, m/z = 465.2 [M+H]).

Preparation of Compound 7:

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet was charged with compound 6 [residue from a previous step, quantitative yield assumed, 52.2 g, 0.11 mol, 1.00 equiv.], and THF (261 mL, 5 vol). The batch was cooled to 0°C and 1,8-diazabicyclo[5.4.0]un-dec-7-ene (17.1 g, 0.11 mmol, 1.00 equiv.) was added keeping the internal temperature in 0-10°C range. After the addition was complete, the cooling bath was removed and the reaction mixture was allowed to warm up to RT and after 2 h, IPC confirmed no starting material remained. The batch was seeded with the product (1.0 g) and was cooled to 0°C. The slurry was stirred at 0°C for 2 h. The product was isolated by vacuum filtration and washed with cold (0°C) THF (50 mL, 1 vol). The solid cake was conditioned for 1 h and dried under vacuum at 40°C for 16 h to afford 7 [47 g, quantitative yield] as a light orange solid with a purity of >99% AUC. The color of the product changed into yellow once the batch was exposed to air for an extended period of time (~ 1 day). Material was isolated with substantial amount DBU, according to proton NMR. However, it did not interfere with the next step. ¹H MR (CDCh): δ 8.71 (s, 1H), 4.03 (s, 2H), 2.57 (s, 3H), 1.85 (m, 10H), 1.51 (s, 9H). LCMS (ESI, m/z = 419.2 [M+H]).

Preparation of Compound 8:

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet was charged with 7 [40.8 g, 0.10 mol, 1.00 equiv.], triethylamine (31.5 g, 0.31 mol, 3.20 equiv.), and dichloromethane (408 mL, 10 vol). The batch was purged with N2 for 15 min and was cooled to 0°C. Triflic anhydride (44.0 g, 0.16 mol, 1.60 equiv.) was added keeping the

internal temperature in 0-10°C range. The batch was stirred at 0°C and after 3 h, IPC confirmed -7.0% (AUC) of 7 remained. [It was speculated that the product was hydrolyzing back into starting material during the analysis.] Once the reaction was deemed complete, the batch was transferred to a 1 L, separatory funnel and was washed with 50% saturated sodium bicarbonate (200 mL, 5 vol). [It was prepared by mixing saturated sodium bicarbonate (100 mL) with water (100 mL)).] The aqueous layer was separated and was extracted with DCM (2×40 mL, 1 vol). The organic layers were combined and concentrated into a residue under reduced pressure and taken to the next step. LCMS (ESI, m/z = 551.6 [M+H]).

Preparation of Compound 9:

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet was charged with compound 8 [residue from a previous step, quantitative yield assumed, 53.7 g, 0.10 mol, 1.00 equiv.], and THF (110 mL, 2 vol). The solvent was removed under vacuum distillation and the procedure was repeated two times. The flask was charged with triethylsilane (22.7 g, 0.20 mol, 2.00 equiv.), and DMF (268 mL, 5 vol). The batch was degassed by five cycles of evacuation, followed by backfilling with nitrogen. The flask was charged with tetrakis(triphenylphosphine)palladium(0) (11.3 g, 0.01 mol, 0.1 equiv.). The batch was heated to 45-50°C, and after 14 h, IPC confirmed no starting material remained. The batch was transferred to a 500 mL, separatory funnel while still warm. The reaction was partitioned between water (5 vol) and ethyl acetate (5 vol). The aqueous layer was extracted with ethyl acetate (3 x3 vol). The organic layers were combined and concentrated down to 2 volumes. The precipitate was filtered and washed with ethyl acetate (2x 1 vol). The solid cake was conditioned for 1 h and dried under vacuum at 40°C for 16 h to afford 9 [27.5 g, 70% yield] as a yellow solid with a purity of -98% AUC. Proton NMR showed some triphenylphosphine oxide present. ¾ NMR (DMSO-i¾):5 9.01 (s, 1H), 7.40 (s, 1H), 4.30 (s, 2H), 2.58 (m, 2H), 2.58 (s, 3H), 1.81 (m, 5H), 1.51 (s, 9H). LCMS (ESI, m/z = 403.4 [M+H]).

Preparation of Compound 10 from the Scheme 2-1 route:

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet was charged 9 (12.8 g, 31.8 mmol, 1.00 equiv.) and dichloromethane (64 mL, 5 vol). Trifluoroacetic acid (18.2 g, 159 mmol, 5.00 equiv.) was added over 20 min and the solution was stirred for 2 h at RT. IPC confirmed reaction was complete. The batch was transferred to a 500 mL, separatory funnel and washed with saturated sodium bicarbonate (200 mL). The aqueous layer was extracted with dichlorom ethane (3 x3 vol). The organic layers were combined and concentrated down to 1 volume. The precipitate was filtered and conditioned for 1 h and dried under vacuum at 40 °C for 16 h to afford 9 [6.72 g, 70% yield] as an off-white solid with a purity of 99.1% AUC. ¾ NMR (DMSO-dis): δ 8.95 (s, 1H), 8.32 (s, 1H), 7.15 (s, 1H), 3.68 (d, J = 1.0 Hz, 2H), 2.86 (m, 2H), 2.57 (s, 3H), 1.92 (m, 2H), 1.73 (m, 3H), 1.39 (m, 3H). LCMS, ESI, m/z = 303.2 [M+H]).

Preparation of Compound 10 from Scheme 2-2 route:

A 50 mL, three-neck flask equipped with a magnetic stirring bar, thermocouple, N2 inlet was charged 14 (680 mg, 1.62 mmol, 1.00 equiv.) and THF (6.8 mL, 10 vol). A I M solution of potassium tert-butoxide (3.2 mL, 3.24 mmol, 2.00 equiv.) in THF was added over 10 min and the solution was stirred for 2 h at RT. IPC confirmed reaction was complete. The batch was acidified with 4 N hydrogen chloride solution in dioxane (2.4 mL, 9.72 mmol, 6.00 equiv.) and stirred for additional 1 h. The batch was transferred to a 500 mL, separatory funnel and washed with saturated sodium bicarbonate (100 mL). The aqueous layer was extracted with ethyl acetate (3 x20 vol). The organic layers were combined and concentrated down to 3volumes and product precipitated. The precipitate was filtered and conditioned for 1 h and dried under vacuum at 40 °C for 16 h to afford 9 [489 mg, quantitative yield] as an off-white solid.

Preparation of Compound 11 :

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet was charged with 10 (9.00 g, 29.8 mmol, 1.00 equiv.), and acetonitrile (180 mL, 20 vol). A solution of Oxone™ (45.9 g, 0.15 mol, 5.00 equiv.) in water (180 mL, 20 vol) was added to the batch over 20 min. The batch was stirred for 2 h and IPC confirmed the reaction was complete. The batch was concentrated down to ½ of the original volume and was extracted with dichloromethane DCM (4x 10 vol). The organic layers were combined; polish filtered and concentrated down to -10 vol of DCM. The product was slowly crystallized out by addition of heptanes (-30 vol). The mixture was cooled to 0°C and the product was filtered and dried under vacuum at 40 °C for 16 h to afford 11 [9.45 g, 95% yield] as an off-white solid with a purity of >99% AUC. ¾ NMR (CDCb): 5 9.24 (s, 1H), 7.78 (s, 1H), 7.46 (s, 1H), 3.89 (d, J= 2.0 Hz, 2H), 3.43 (s, 3H), 2.98 (m, 2H), 2.10 (m, 2H), 1.86 (m, 3H), 1.50 (m, 3H). LCMS (ESI, m/z = 335.2 [M+H]).

Preparation of Compound 13:

A 250 mL, single-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet, and reflux condenser was charged with 4-chloro-2-(methylthio)pyrimidine-5-carbaldehyde (2.00 g, 10.6 mmol, 1.00 equiv.), spirolactam 4 (1.96 g, 11.7 mmol, 1.10 equiv.), DIPEA (2.74 g, 21.2 mmol, 2.00 equiv.), and fert-butanol (20 mL, 10 vol). The batch was heated to 80-85 °C, and after 24 h, IPC confirmed no aldehyde 12 remained. The batch was cool to RT and concentrated into a residue, which was loaded on silica gel column. The product was eluted with ethyl acetate/heptanes (0% to 100%). The product containing fractions were pulled out and concentrated to afford 13 [0.98 g, 29% yield] as an off-white solid.

Preparation of Compound 14:

A 500 mL, three-neck flask equipped with a mechanical overhead stirrer, thermocouple, N2 inlet was charged with 13 [0.98 g, 3.00 mmol, 1.00 equiv.], Boc-anhydride (4.90 g, 21.5 mmol, 7.00 equiv.), DMAP (36 mg, 0.30 mmol, 0.10 equiv.), and dichloromethane (7 mL, 7 vol). The batch was stirred for 3 h at RT. IPC confirmed no starting material remained. The batch was cool to RT and concentrated into a residue, which was loaded on silica gel column. The product was eluted with ethyl acetate/heptanes (0% to 100%). The product containing fractions were pulled out and concentrated to afford 14 [0.98 g, 29% yield] as an off-white solid.

Preparation of Compound 15:

To a suspension of methyl glycinate (500 g, 3.98 mol, 1 eq) in DCM (10 L) was added

TEA dropwise at rt under nitrogen atmosphere, followed by the addition of cyclohexanone (781 g, 7.96 mol, 2 eq) dropwise over 15 min. To the resulting mixture was added TMSCN (591 g, 5.97 mol, 1.5 eq) dropwise over 1 hour while maintaining the internal reaction temperature below 35

°C. After stirred at rt for 2 hrs, the suspension became a clear solution. The progress of the reaction was monitored by H- MR.

When the methyl glycinate was consumed completely as indicated by H-NMR analysis, the reaction was quenched by water (5 L). The layers were separated. The aqueous layer was extracted with DCM (1 L). The combined organic phase was washed with water (5 L X 2) and

dried over Na₂S04 (1.5 Kg). After filtration and concentration, 1.24 Kg of crude 15 was obtained as oil.

The crude 15 was dissolved in IPA (4 L). The solution was treated with HC1/IPA solution (4.4 mol/L, 1.1L) at RT. A large amount of solid was precipitated during the addition. The resulting suspension was stirred for 2 hrs. The solid product was collected by vacuum filtration and rinsed with MTBE (800 mL). 819 g of pure 15 was obtained as a white solid. The yield was 88.4%. ¾- MR (300 MHz, CD3OD) 4.20 (s, 2H), 3.88 (s, 3H), 2.30-2.40 (d, J = 12 Hz, 2H), 1.95-2.02 (d, J = 12 Hz, 2H), 1.55-1.85 (m, 5H), 1.20-1.40 (m, 1H).

Preparation of Compound 16:

To a solution of 15 (10 g, 43 mmol) in MeOH (100 mL) was added methanolic hydrochloride solution (2 .44 mol/L, 35.3 mL, 2 eq) and Pt02 (0.5 g, 5 wt %). The reaction suspension was stirred with hydrogen bubble at 40 °C for 6 hours. H- MR analysis showed consumption of 15. To the reaction mixture was added K2CO3 (15 g, 108 mmol, 2.5 eq) and the mixture was stirred for 3 hrs. The suspension was filtered and the filtrate was concentrated to dryness. The residual oil was diluted with DCM (100 mL) and resulting suspension was stirred for 3 hrs. After filtration, the filtrate was concentrated to provide crude 16 (6.6 g) as an oil. The crude 16 was diluted with EtOAc/hexane (1 : 1, 18 mL) at rt for 2 hrs. After filtration, 16 (4 g) was isolated. The obtained 16 was dissolved in DCM (16.7 mL) and hexane (100 mL) was added dropwise to precipitate the product. After further stirred for 1 h, 2.8 g of the pure 16 was isolated as a white solid. The yield was 39%. HPLC purity was 98.3%; MS (ESI): 169.2 (MH+); 1 H-NMR (300 MHz, D2O) 3.23 (s, 3H), 3.07 (s, 3H), 1.37-1.49 (m, 10H).

Preparation of compound 19:

5-(4-methylpiperazin-l-yl)pyridin-2-amine (803.1 g; 3.0 equivalents based on sulfone 11) was charged to a 22 L flask. The flask was blanketed with N₂ and anhydrous THF added (12.4 kg). The resulting black-purple solution was cooled in an ice bath to < 5°C. 1M LiHMDS (4.7 L; 1.2 equivalents based on sulfone 11) was added via an addition funnel in three equal additions to keep the temperature below 10°C. Upon the completion of the addition, the reaction mixture was warmed to 16°C. The sulfone 11 (455.1 g; 1.00 equivalents) was added in five additions. Reaction proceeded until HPLC analysis of an IPC sample indicated less than 3% of sulfone 11 remained.

To quench the reaction, the contents of the 22L flask were transferred to a 100 L flask containing water. After stirring for 30 minutes at <30°C, the crude product was collected by filtration, washed with water and dried to afford 19 (387 g, 99.1% purity, 63.7% yield).

Preparation of compound 20:

5-(4-isopropylpiperazin-l-yl)pyridin-2-amine (1976.2 g; 3.0 equivalents based on sulfone 11) was charged to a 50 L flask. The flask was blanketed with N2 and anhydrous THF added (10.7 kg). The resulting black-purple solution was cooled in an ice bath to < 5°C. 1M LiHMDS (9.6 kg; 3.6 equivalents based on sulfone) was added via an addition funnel at a rate to keep the temperature below 10°C. Upon the completion of the addition, the reaction mixture was warmed to 16°C over 120 minutes by removing the ice bath. The sulfone (1000 g; 1.00 mol) was added in five additions. The reaction proceeded until HPLC analysis of an IPC sample indicated less than 1% of sulfone 11 remained. After completion of the reaction, ammonium chloride was added to the reaction mixture. The mixture stirred at < 32°C for at least 30 minutes and the solids collected by filtration to afford 20 (900 g, 99.1% purity, 64.2% yield).

Alternate Route to Spirolactam via cyclohexanone:

Scheme 2-7

26

In one embodiment the spirolactam is made via the synthetic scheme above. By reducing the nitrile group before addition of the glycinate group the reaction sequence proceeds in higher yield. The chemistry used in Step 1 is described in the literature (J. Org. Chem. 2005, 70,8027-8034), and was performed on a kilogram scale. The chemistry to convert Compound 24 into the

spirolactam was also demonstrated on kilogram scale. The Boc protection of Compound 23, is carried out at -70°C in order to limit formation of the di-Boc protected product. Experimental details of a 200 g pilot run are described below.

Step 1

200 g of cyclohexanone 21 was converted to 22 using Ti(Oi-Pr)₄ /TMSCN/NH3. After work-up, 213 g of 22 was obtained. The H- MR was clean. The yield was 84%. The titanium salts were removed by vacuum filtration. In one embodiment, the titanium salts are removed by centrifugation or Celite filtration.

Step 2

190 g of 22 was mixed with LAH (2 eq) in MTBE for 30 minutes at 45°C. After work-up, 148 g of crude 23 was obtained.

Step 3

136 g of the crude 23 from step 2 was converted to 24 with 0.9 eq of B0C2O at -70°C. The reaction was completed and worked up. After concentration, 188 g of 24 was obtained. The yield was 86%. The H-NMR and C-NMR spectra confirmed that the compound was pure.

Step 4

188 g of 24 was subjected to methyl 2-bromoacetate and K2CO3 in acetonitrile to afford 25. 247 g of crude 25 was obtained.

Step 5

247 g of 25 was subjected to TFA in DCE heated to reflux to afford 26. After work-up, 112 g of 6 as TFA salt was obtained. H- MR was clean.

Step 6

26 27

Compound 26 was stirred in EtOH in the presence at room temperature overnight to afford 27. In one embodiment DCM is used as the solvent instead of EtOH.

Example 3. Purge of residual palladium from Step 5 Scheme 2-1:

Since palladium was used in Step 5 of Scheme 2-1, the levels of residual Pd present in the subsequent synthetic steps was determined. Table 2 below and Figure 3 show the palladium levels in the isolated solids.

Table 2

The material after Step 5 was isolated containing 1.47% (14700 ppm) of residual palladium. This data represents the highest level of palladium in the worst case scenario. The workup conditions of the latter steps purged nearly all of the palladium and the final product, 19 bis HC1 salt, contained 14 ppm of Pd, which is below the standard 20 ppm guidline. The Pd levels will likely be even lower once the catal st loading is optimized in Step 5.

19

The process developed in this route was a significant improvement over the one used for the first generation synthesis. Overall, the scheme consists of seven steps with five isolations, all by crystallization. No silica column chromatography is employed in the synthesis, which makes the process highly scalable. The process workup conditions can successfully purge the 1.47% of residual palladium after step 5 of Scheme 2-1.

///////////////TRILACICLIB, G1T28, G1T 28, SHR 6390, PHASE 2, G1 Therapeutics, Inc.

CN1CCN(CC1)C2=CN=C(C=C2)NC3=NC=C4C=C5C(=O)NCC6(N5C4=N3)CCCCC6