α-乙酰基二硫缩烯酮α碳原子的酰化反应

Acylation of α-Acetyl Ketendithioacetals with Acyl Chloride

As a kind of versatile synthons, α-oxoketene dithioacetals have found their wide utilizations in organic synthesis. Owing to the interaction between two electron donating groups(RS) and an electron withdrawing group in the α position, the α-carbon atom of α-EWG ketene S,S-acetals shows a high nucleophilicity. In this paper, the reactions of α-acetyl cyclic ketendithioacetals with a series of acyl chlorides were performed and a new route to the C～C bond formation reaction at the α-carbon atom of α-oxoketene dithioacetals was described. By the above reactions, α-acetyl-α-acyl ketendithioacetals were prepared with good to high yields(55%～82%) via the acylation of α-acetyl cyclic ketendithioacetals at the α-carbon atom of α-acetyl ketendithioacetals mediated by titanium tetrachloride in dry dichloromethane at reflux temperature. The mechanism of the acylation between compound 1 and acyl chloride was proposed, which belongs to nucleophilic addition-elimination reaction.

As a kind of versatile synthons, α-oxoketene dithioacetals have found their wide utilizations in organic synthesis. Owing to the interaction between two electron donating groups（RS） and an electron withdrawing group in the α position, the α-carbon atom ofα-EWG ketene S, S-acetals shows a high nucleophilicity. In this paper, the reactions of α-acetyl cyclic ketendithioacetals with a series of acyl chlorides were performed and a new route to the C--C bond formation reaction at the α-carbon atom of a-oxoketene dithioacetals was described. By the above reactions, α-acetyl-α-acyl ketendithioacetals were prepared with good to high yields （55%--82%） via the acylation of a-acetyl cyclic ketendithioacetals at the α-carbon atom of α-acetyl ketendithioacetals mediated by titanium tetrachloride in dry dichloromethane at reflux temperature. The mechanism of the acylation between compound 1 and acyl chloride was proposed, which belongs to nucleophilic additionelimination reaction.