p-Toluenesulfonic acid → 1-Methyl-1,3,4,9-tetrahydro-6-(phenylmethoxy)pyrano[3,4-b]indole-1-aceticacid, ethyl ester

Participants

Reaction Steps

A mixture consisting of 5-benzyloxytryptophol (4.5 g, 0.017 mol), benzene (200 mL), ethyl acetoacetate (3.4 g, 0.026 mol) and p-toluenesulfonic acid (0.5 g) is refluxed for 2.5 hours using a Dean-stock trap to remove the water. The reaction mixture is cooled to room temperature and washed with 5% sodium bicarbonate, (1×200 mL), water (200 mL) and brine (100 mL), dried (MgSO4), filtered and concentrated to give 8.0 g of crude product as a thick oil, which is flash chromatographed on silica gel using 20% ethyl acetate/hexane as an eluent to afford 5.5 g oil which solidifies upon standing, m.p. 96°-98° C.

Provenance & Evidence