Catalytic Asymmetric Addition of Meldrum’s Acid, Malononitrile, and 1,3-Dicarbonyls to<i>ortho</i>-Quinone Methides Generated In Situ Under Basic Conditions
unstable ortho‐quinone methides (o‐QMs) in catalyticasymmetric settings is presented. The enantioselective reactions are catalysed by bifunctional organocatalysts, and the o‐QM intermediates are formed in situ from 2‐sulfonylalkyl phenols through base‐promoted elimination of sulfinic acid. The use of mild Brønsted basicconditions for transiently generating o‐QMs in catalyticasymmetric processes is unprecedented
Organocatalytic asymmetric addition of thioglycolates to <i>o</i>-quinone methides: a route to 5-substituted-5<i>H</i>-benzoxathiepine-2(3<i>H</i>)-ones
作者:Chandan Gharui、Satya Prakash、Deepak Chopra、Subhas Chandra Pan
DOI:10.1039/d0ob00568a
日期:——
Herein we have developed the first enantioselective synthesis of 5-substituted-5H-benzoxathiepine-2(3H)-ones. 2-Sulfonylmethyl phenols and thioglycolates were employed as reaction partners in this method. The desired thia Michael products were obtained via bifunctional squaramide catalyzed conjugate addition reaction to in situ generated o-quinone methides and then basic hydrolysis followed by cyclization