Hydrochloric Acid → (2S)-Methyl 2-(1-(3-chloropyridin-2-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-yloxy)-3-isopropoxypropanoate

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Reaction Conditions

Reaction Steps

Sodium hydride (1.84 g, 45.9 mmol) was added to a stirred solution of (S)-methyl 2-hydroxy-3-isopropoxypropanoate (Intermediate C7a) (6.0 g, 30.6 mmol) in anhydrous THF (200 mL) at 0° C., under nitrogen. The resulting suspension was stirred at 0° C. for 10 minutes and then a solution of 4-chloro-1-(3-chloropyridin-2-yl)-1H-pyrazolo[3,4-d]pyrimidine (Intermediate B15) (8.14 g, 30.59 mmol) in dry THF (50 mL) was added dropwise, maintaining the temperature below 5° C. The reaction mixture was stirred at 0° C. for 10 minutes. Then allowed to warm to ambient temperature and stirred for 1 hour. The reaction mixture was neutralised with 1M HCl. The majority of the THF was evaporated in vacuo and then EtOAc (100 mL) was added. The organic layer was separated and the aqueous layer re-extracted with EtOAc (2×100 mL). The combined organics were washed with saturated brine (75 mL), dried (MgSO4) and evaporated. The crude product was purified by flash silica chromatography, elution gradient 20 to 70% EtOAc in isohexane to afford (2S)-methyl 2-(1-(3-chloropyridin-2-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-yloxy)-3-isopropoxypropanoate (7.76 g, 64.8%), ee 53%. A sample of this (1.48 g) was purified by preparative chiral-HPLC on a 50 mm 20um chiralcel OJ column, eluting with 30% isopropanol in isohexane (modified with 0.1% TEA), to give (2S)-methyl 2-(1-(3-chloropyridin-2-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-yloxy)-3-isopropoxypropanoate (1.03 g, 99% ee). 1H NMR (400 MHz, DMSO-d6) δ 1.10-1.14 (6H, m), 3.68-3.75 (4H, m), 3.98-4.00 (2H, m), 5.80-5.82 (1H, m), 7.74-7.77 (1H, m), 8.33-8.35 (1H, d), 8.59 (1H, s), 8.64 (1H, s), 8.67-8.68 (1H, m); m/z (ESI+) (M+H)+=392; HPLC tR=2.13 min.

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