Donor–acceptor cyclopropanes were reacted under Lewis acid catalysis with 3-thioxocyclobutanones as surrogates for disubstituted thioketenes. A broad scope of 2-substituted tetrahydrothiophenes with a semicyclic double bond was obtained under mild conditions with high functional group tolerance and in excellent yield. A sequence of a formal [3 + 2]-cycloaddition followed by the subsequent release of disubstituted ketene is postulated as the mechanism.

中文翻译：

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路易斯酸催化将噻吨酮正式插入给体-受体环丙烷中

供体-受体环丙烷在路易斯酸催化下与3-硫代氧代环丁酮作为双取代硫代乙烯酮的代用品反应。在温和的条件下，具有高官能团耐受性和优异的收率，获得了具有半环双键的2-取代四氢噻吩。推测有一个正式的[3 + 2]-环加成序列，然后随后释放出二取代的乙烯酮作为该机理。