Regiospecific arylation of 1,4-benzoquinone cyanohydrin phosphate: synthesis of 3-aryl-4-hydroxybenzonitriles

Abstract

Reaction of 1,4-benzoquinones (1a,b) with diethyl phosphorocyanidate and lithium cyanide was found to give the monocyanophosphates (2a,b). When catalysed by BF₃·OEt₂, the cyanophosphates (2a,b) reacted with aromatic and heteroaromatic compounds (indole, thiophene, and furan derivatives) to give 3-aryl-4-hydroxybenzonitriles. Under the same conditions ethyl 1-methylindole-2-carboxylate and 2,5-dimethylfuran were converted into 6-oxobenzopyrano[3,4-b]indole-2carbonitriles (15a,b) and benzofuran-5-carbonitriles (22a,b) by reaction with the cyanophosphates (2a,b), respectively.