Diisopropylethylamine → (R)-ethyl 5-(2-(5-fluoro-2-methylpyridin-3-yl)pyrrolidin-1-yl)pyrazolo[1,5-a]pyrimidine-3-carboxylate

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Reaction Steps

To a solution of ethyl 5-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (Preparation B, Step A, 372 mg, 1.8 mmol) in DMF (10 mL) was added (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (874 mg, 1.98 mmol). The mixture was stirred at ambient temperature for 10 minutes then treated with DIEA (1.57 mL, 8.99 mmol) and (R)-5-fluoro-2-methyl-3-(pyrrolidin-2-yl)pyridine dihydrochloride (455 mg, 1.80 mmol). After stirring at ambient temperature for 4 hours the mixture was partitioned between 10% citric acid (50 mL) and EtOAc (50 mL). The layers were separated and the aqueous layer was extracted with EtOAc (2×30 mL). The combined organic phases were washed successively with water (30 mL), saturated NaHCO3 (30 mL), water (30 mL) and brine (2×30 mL), then dried over Na2SO4, filtered and concentrated. The residue was purified by silica gel column chromatography eluting with 1% MeOH/DCM to afford the product as white foam (480 mg, 72% yield). MS (apci) m/z=370.0 (M+H).

Provenance & Evidence