Methanol → 4-Hydroxyiminomethyl-9-phenyl-2,3,4,9-tetrahydrothiopyrano[2,3-b]indole

Participants

Reaction Steps

A solution of the product of the above (2) (3.71 g) in pyridine (75 ml) is heated at 110° C. for 70 minutes. After cooling, methanol (25 ml) and hydroxyamine hydrochloride (2.2 g) are added thereto. The mixture is stirred at room temperature for 50 minutes and evaporated. The residue is acidified with ice-cooled 3 N-hydrochloric acid and extracted with chloroform. The extract is evaporated to give oily residue. The residue is chromatographed on a column of silica gel and eluted with benzene. The eluate is evaporated to give 4-hydroxyiminomethyl-9-phenyl-2,3,4,9-tetrahydrothiopyrano[2,3-b]indole (3.28 g). The product is dissolved into tetrahydrofuran (55 ml) and lithium aluminium hydride (1.4 g) is added thereto at room temperature. The mixture is refluxed for 1 hour. Ethyl acetate, an 10% aqueous solution of sodium hydroxide and water are successively added thereto. The precipitate is collected by filtration, washed with ethyl acetate and chloroform, and added to the filtrate. The organic layer is separated, washed with water, dried and evaporated to give the free base of the title compound as an oil.

Provenance & Evidence