Access to Dibenzofurans through Dimerization/Trimerization of Cyclohexanones Followed by Dehydroaromatization.

A novel and efficient method for the synthesis of unsymmetrical substituted dibenzofurans has been developed, which can selectively produce disubstituted dibenzofurans and trisubstituted dibenzofurans products under metal-free conditions. This approach starts from cheap and available nonaromatic cyclohexanones, affording a simple and efficient access to unsymmetrical substituted dibenzofurans.