Synthesis of Spiro[benzo[h]chromene-4,3′-indoles] and Spiro[benzo[f]chromene-1,3′-indoles]

Abstract

New spiro heterocycles, spiro[benzo[h]chromene-4,3′-indoles] and spiro[benzo[f]chromene-1,3′-indoles], have been synthesized in 50–60% yield by three-component condensation of substituted isatins with malononitrile or ethyl cyanoacetate and naphthalen-1-ol or naphthalen-2-ol. The described reactions follow a cascade cyclization pathway and provide a regioselective method of synthesis of the title compounds.