Citric Acid → (2S)-Methyl 3-[2-(tert-butyl-diphenylsilyl)oxyethoxy]-2-[1-(3-chloro-2-methylphenyl)pyrazolo[4,5-e]pyrimidin-4-yl]oxypropanoate

Participants

Reaction Conditions

Reaction Steps

Sodium hydride (60% in mineral oil) (0.191 g, 4.77 mmol) was added in one portion to (S)-methyl 3-(2-(tert-butyldiphenylsilyloxy)ethoxy)-2-hydroxypropanoate (Intermediate AB3) (1.6 g, 3.97 mmol) in THF (15 mL) cooled to 0° C. under nitrogen. Slow gas evolution. The resulting suspension was stirred at 0° C. for 10 minutes. A solution of 4-chloro-1-(3-chloro-2-methylphenyl)-1H-pyrazolo[3,4-d]pyrimidine (Intermediate AE5) (1.109 g, 3.97 mmol) in THF (10 mL) was added dropwise over 2 minutes. The resulting suspension was stirred at 0° C. for 10 minutes, allowed to warm to ambient temperature and stirred for 72 hours to give an orange solution. Cooled to ˜5° C., 1M citric acid (30 mL) added, the mixture stirred for 10 minutes, diluted with EtOAc (50 mL), the organic phase separated and washed sequentially with water (25 mL) and saturated brine (25 mL). The organic layer was dried (MgSO4), filtered and evaporated in vacuo. The crude product was purified by flash silica chromatography, elution gradient 20 to 50% EtOAc in isohexane to afford the product (2.1 g, 82%). 1H NMR (400 MHz, DMSO) δ 0.95 (9H, s), 2.03 (3H, s), 3.68 (3H, s), 3.67-3.74 (2H, m), 3.78-3.82 (2H, m), 4.04-4.07 (1H, m), 5.87-5.91 (1H, m), 7.37-7.45 (8H, m), 7.61-7.65 (4H, m), 7.67-7.69 (1H, m), 8.48 (1H, s), 8.57 (1H, s); m/z (ESI+) (M+H)+=645; HPLC tR=3.65 min.

Provenance & Evidence