Enantioselective Friedel–Crafts reactions between phenols and N-tosylaldimines catalyzed by a leucine-derived bifunctional catalyst
作者:Guo-Xing Li、Jin Qu
DOI:10.1039/c2cc31735d
日期:——
Enantioselective FriedelâCrafts reactions between phenols and N-tosylaldimines were developed using a bifunctional catalyst readily prepared from L-leucine. The chiral benzylic amine products were obtained in high yields (up to 96% yield) and good to high enantiomeric excesses (up to 95% ee).
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
Development of Bifunctional Chiral Thioureas and Thiosquaramides in the Synthesis of Betti Bases
作者:Martyna Malinowska、Anna Zawisza
DOI:10.3390/molecules28237835
日期:——
Bifunctional thioureas and, for the first time, bifunctional thiosquaramides as organocatalysts were used in the asymmetric Betti reaction involving 1-, 2-naphthols and hydroxyquinoline with N-tosylimine and ketimine. The described methodology affords direct access to chiral aminoarylnaphthols in excellent yield (up to 98%) with high enantioselectivity (up to 80% ee) and enantioenriched 3-amino-2-oxindoles