Gold-catalyzed synthesis of 1H-isochromene-4-carbaldehydes via oxidative cascade cyclization

An efficient gold-catalyzed formation of indenylidene-derived 1H-isochromene-4-carbaldehydes from substituted 1,5,10-triyne-O-silanes was developed under mild reaction conditions. In this reaction gold- catalyzed selective oxidation, 1,2-migration of enynyl group, nucleophilc addition and then 5-endo-dig cyclization took place regioselectively. The indenylidene-derived isochromene-4-carbaldehydes were synthesized in moderate to very good yields via the formation of a new C-C and C-O bonds in one-pot.