Turkish Journal of Chemistry, Vol.42, No.2, 237-+, 2018
Tetrahydronaphthalene as a precursor of new series of chalcones, flavanones, and flavones
An efficient synthetic route for a novel series of chalcones 2a-2d as well as for the corresponding flavanones 3a-3d and flavones 4a-4d, using functionalized tetrahydronaphthalene (THN), is described herein. The Claisen-Schmidt condensation of such THN and aromatic aldehydes, in the presence of an aqueous solution of KOH (40%), selectively gives the expected chalcones 2a-2d, which may further undergo an intramolecular oxa-Michael addition using piperidine, affording the corresponding flavanones 3a-3d in high yields. Alternatively, treatment of such chalcones 2a-2d with I-2/DMSO provides rapidly, in a one-pot oxidative cyclization, a series of flavones 4a-4d in excellent yields ranging from 85% to 90%.