Methanol → 1-Ethyl-1,3,4,9-tetrahydro-6-(phenylmethoxy)pyrano[3,4-b]indole-1-acetic acid

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Reaction Steps

A mixture consisting of the ester (29.0 g, 0.0765 mol) of Step A, methanol (800 mL), water (50 mL) and potassium hydroxide (16.0 g, 0.29 mol) is refluxed for 4 hours. The reaction mixture is cooled to room temperature, concentrated and diluted with water (500 mL). The aqueous layer is washed with ether (2×200 mL) and made acidic with a 1:1 mixture of concentrated HCl and water to pH 2.71 is extracted with chloroform (4×300 mL) and the combined chloroform layers are washed once with water (2×300 mL), once with brine (300 mL), dried (MgSO4), filtered and concentrated to give 26.0 g of title compound, m.p. 163°-165° C.

Provenance & Evidence