p-Toluenesulfonic acid → 1,3,4,9-Tetrahydro-1,1-diethyl-6-(phenylmethoxy)pyrano[3,4-b]indole

Participants

Reaction Steps

A mixture consisting of 5-benzyloxytryptophol (7.0 g, 0.0262 mol), diethyl ketone (10 mL), benzene (400 mL) and p-toluene sulfonic acid is refluxed for 3.5 hours using a Dean-Stark tap to remove the water. The reaction mixture is cooled to room temperature, washed with 5% sodium bicarbonate, water (200 mL), brine (200 mL), dried (MgSO4), filtered and concentrated to give 9.9 g of crude product. The crude product is flash chromatographed on silica gel using 15% ethyl acetate/hexane as an eluent to afford 6.5 g of pure title compound.

Provenance & Evidence