(2-Aryl-2-cyanoethenyl)ketenes---annulated cyanophenols from azidoquinones

Annulated cyanophenols are the products derived from the thermolysis of 3,6-diaryl-2,5-diazido-1,4-benzoquinones in the presence of an alkyne. The transformation is envisaged to involve the following steps: 1)thermal fragmentation of the azidoquinones to arylcyanoketenes, 2) cycloaddition of the ketenes to an alkyne to give 4-aryl-4-cyanocyclobutenones, 3) electrocyclic ring opening of the cyclobutenone to generate (2-aryl-2-cyanoethenyl)ketenes, and 4) ring closure of the conjugated ketenes to give the annulated cyanophenol products. Similarly, analogous products are obtained from the thermolysis of 4-aryl-3-azido-6-chloro-5-ethoxy-1,2-benzoquinones.