Potassium cyanate → 4-Cyano-2,3,4,9-tetrahydrothiopyrano[2,3-b]indole

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Reaction Steps

The product of the above (2) (13.2 g) is dissolved in a mixture of ethanol (300 ml) and triethylamine (20 ml). The solution is refluxed for 1 hour and further 2 hours after addition of a solution of potassium cyanate (25 g) in a mixture of ethanol (170 ml) and water (80 ml) and evaporated to remove the solvent. The residue is extracted with ether after addition of water. The extract is washed with water, dried and evaporated to remove the solvent. The oily residue (15 g) is chromatographed on an column of silica gel (450 g) and eluted with benzene. The eluate is condensed to give the title compound as crystals melting at 125°-126° C. Yield: 69%

Provenance & Evidence