3,4-dihydro-2H-pyran → 5-bromo-1-(oxan-2-yl)-1H-indazole

Participants

Reaction Steps

A 250 mL round bottom flask with was charged with 5-bromo-1H-indazole (25.00 g, 0.127 mol, 1.0 eq), and dichloromethane (100 mL). To the suspension was added dihydropyran (32.0 g, 0.381 mol, 3.0 eq) and a catalytic amount of pyridinium para-toluenesulfonate (3.19 g, 0.0127 mol, 0.10 eq). The mixture was stirred overnight, and in the morning was a clear solution. The methylene chloride was washed sequentially with saturated sodium bicarbonate, 10% citric acid, and brine, and was then evaporated. Chromatography of the residue on silica gel, eluting with EtOAc/heptane, gave the title compound as a colorless liquid (28.00 g, 79%).

Provenance & Evidence