An Efficient Synthesis of 4-Hydroxy-1H-indole-2-carbonitrile and Its Conversion to DPI 201–106

A three-step synthesis of 4-hydroxy-1H-indole-2-carbonitrile (3) from commercially available 1,5,6,7-tetrahydro-4H-indol-4-one (4) via cyanation and subsequent halogenation/ dehydrohalogenation proceeds in 84% overall yield. The conversion of 3 into positive inotrope DPI 201–106 (1) is also described.