An efficient N-heterocyclic carbene (NHC) catalyzed sulfa-Michael addition (SMA) between enals and thiols has been developed. Under the catalysis of 10 mol% stable free carbene IPr and with 20 mol% hexafluoroisopropanol (HFIP) as an additive, enals react with a variety of thiols to afford the SMA adducts in 54–98% yields. In this process, the free carbene preferentially interacts with thiols through hydrogen-bonding and no NHC-catalyzed extended Umpolung transformations were observed.

中文翻译：

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N-杂环卡宾催化的磺胺-迈克尔加成

已经开发了一种有效的N-杂环卡宾（NHC）催化的烯醛和硫醇之间的磺胺-迈克尔加成（SMA）。在10摩尔％稳定的游离卡宾IPr的催化下，并以20摩尔％的六氟异丙醇（HFIP）作为添加剂，使烯醛与各种硫醇反应，以54-98％的产率提供SMA加合物。在此过程中，游离卡宾通过氢键优先与硫醇相互作用，并且未观察到NHC催化的扩展Umpolung转化。