Gold(I)-Catalyzed Regioselective Synthesis of Indenylidene Derivatives via 1,5-Acryl Migration.

A novel gold (I)-catalyzed synthetic strategy has been achieved for an efficient construction of indenylidene derivatives from substituted 1,6-diynes. This reaction describes the unique reactivity of gold catalysis in facilitating the intramolecular [3,3]-sigmatropic rearrangement, 5-exo dig cyclization followed by 1,5-migration of acryl group, resulting in the formation of substituted indenylidenes. Various substituted indenylidenes were successfully synthesized with up to 92 % yields. In this protocol, two new C-C bonds were sequentially formed atom economically in one pot.

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, nucleophilic 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 new C-C and C-O bonds in one pot.