Cyclobutenone Ethylenedithioacetals and Their Ready Electrocyclic Ring Opening

Abstract

Reported here is a general regiospecific synthesis of cyclobutenedione monoethylendithioacetals which readily undergo ring opening after addition of an organolithium reagent. The generated acyclic enols either tautomerize to the corresponding carbonyl compounds or can be trapped as silylenol ethers, which serve as electron rich dienes in Diels-Alder additions with tetracyanoethylene or maleic anhydride.

Key words

cyclobutenones - dithioacetals - transthioacetalization - electrocyclic ring opening - Diels-Alder reaction

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