Enantioselective synthesis of γ-tetrasubstituted nitrosulfonyl carboxylates and amides via<scp>l</scp>-tert-leucine-derived-squaramide catalyzed conjugate addition of nitrosulfones to acrylates and acrylamides
作者:Kalisankar Bera、Irishi N. N. Namboothiri
DOI:10.1039/c4ob00344f
日期:——
Michael addition of α-nitrosulfones to aryl- and alkyl acrylates and acrylamides proceeds in the presence of 5–10 mol% of an amino acid derived new organocatalyst to provide γ-tetrasubstituted γ-nitro-γ-sulfonyl carboxylates and amides in excellent yields and enantioselectivities. Scale-up of the reaction to multi-grams, convenient recovery of the catalyst and its recyclability without any drop in
Enantioselective synthesis of α-nitro-δ-ketosulfones via a quinine–squaramide catalyzed conjugate addition of α-nitrosulfones to enones
作者:Kalisankar Bera、Irishi N. N. Namboothiri
DOI:10.1039/c3cc45985c
日期:——
Conjugate addition of α-nitrosulfones to vinyl ketones in the presence of 0.2 mol% of a quinineâsquaramide organocatalyst afforded α-nitro-δ-ketosulfones possessing a tetrasubstituted chiral center in excellent yield and enantioselectivity in most cases. This strategy also offers a facile and convenient entry into γ-sulfonylhydroxamates that are one carbon homologs of potent enzyme inhibitors.