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.