Conjugate addition of unactivated thiols to α,β-unsaturated ketones catalyzed by a bifunctional rhenium(V)–oxo complex
作者:Allan Peng、Ross Rosenblatt、Kristine Nolin
DOI:10.1016/j.tetlet.2012.03.075
日期:2012.5
found to be an efficient bifunctional catalyst for the 1,4-addition of thiols to α,β-unsaturatedketones. The addition of thiophenol derivatives and alkyl thiols proceeds under mild reaction conditions without pre-activation of the thiol or exogenous base. Reactions of aryl, alkyl, and cyclic enones produce the corresponding β-sulfanyl ketones in good to excellent yield.
Reductivecyclization of sulfur-containing substrates 1 and 5 with samarium diiodide afforded the corresponding thiochroman derivatives with excellent diastereoselectivities. Cyclization of 1 is facilitated by geminal dimethyl substitution, which accelerates the reductive coupling and prevents samarium diiodide induced dehalogenation. Bromo-substituted dihydrothiochroman derivative 8 was further functionalized