Silver-Catalyzed Highly Regioselective Synthesis ofα-Carbonyl Furans from Enynones
摘要:
A general and efficient method for the synthesis of a wide range of alpha-carbonyl furans is described here. The cyclization of enynone is catalyzed by AgBF4 in a fluorous biphasic system of perfluorodecalin and N,N-dimethylformamide. A variety of chain ketone and cyclic ketone substrates were used to investigate the scope of the reactions.
Stoichiometric ceric ammonium nitrate (CAN) and a catalytic amount of Pd(PPh3)2Cl2 (5 mol %) can rapidly produce multisubstituted 2-ketofuran-4-carboxylate esters from 2-propargylic 1,3-ketoesters via oxidative O-cyclization reaction. Pd(PPh3)2Cl2 was found to be the crucial catalyst as its inclusion greatly enhanced the rate of the reaction and cleanly afforded the products within minutes. Over 30