With esters and thioesters

On the other hand, the reactions of 2-lithio-2-trimethylsilyl-l,3-dithiane with esters and thioesters give not the ketene dithioacetals, but the 2-acyl-l,3-dithianes 81 (Scheme 2.50). The possibly formed silyl enol ethers 80 undergo subsequent hydrolysis to give 81 [141],... 

Scheme 2.50. Reaction of 2-lithio-2-trimethylsilyl-l, 3-dithiane with esters and thioesters.

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