Organocatalytic Iminium Ion/Carbene Reaction Cascade for the Formation of Optically Active 2,4-Disubstituted Cyclopentenones
作者:Christian Borch Jacobsen、Kim L. Jensen、Jonas Udmark、Karl Anker Jørgensen
DOI:10.1021/ol2018104
日期:2011.9.16
An organocatalytic iminium ion/N-heterocyclic carbene (NHC) cascade reaction between β-keto phenyltetrazolesulfones and α,β-unsaturated aldehydes, providing direct access to opticallyactive 2,4-disubstituted cyclopent-2-enones, has been developed. The products are isolated in good yields with high enantioselectivities.
Sulfonyl hydrazine is a new functionality for the Lewis base organocatalysis. Nα-substituted camphorsulfonyl hydrazines (CaSH) are effective organocatalysts for the asymmetric aza-Michael addition to α,β-unsaturated aldehydes with enantioselectivity of up to 90%.
An organocatalytic approach to enantiomerically enriched α-arylcyclohexenones and cyclohexanones
作者:Sara Duce、María Jorge、Inés Alonso、José Luis García Ruano、M. Belén Cid
DOI:10.1039/c1ob06356a
日期:——
The presence of a p-nitrophenyl group converts acetone into an excellent and versatile nucleophile in organocatalytic processes, able to react with α,β-unsaturated aldehydes affording β-substituted α-arylcyclohexenones via a Michael reaction/aldol reaction/dehydration sequence, which occurs in good yields, ee up to 96% and complete diastereoselectivity. The resulting compounds are excellent synthons for the diastereoselective preparation of a variety of synthetically useful polysubstituted cyclohexanones and derivatives.
One-Pot Asymmetric Synthesis of Seven-Membered Carbocycles Cyclohepta[<i>b</i>]indoles via a Sequential Organocatalytic Michael/Double Friedel–Crafts Alkylation Reaction
作者:Nitin S. Dange、Bor-Cherng Hong、Chih-Ching Lee、Gene-Hsiang Lee
DOI:10.1021/ol4016749
日期:2013.8.2
enantioselective synthesis of highly functionalized cyclohepta[b]indoles with high enantioselectivity (up to 96% ee). The process combines an enantioselective organocatalytic Michael addition and a highly efficient double Friedel–Crafts reaction sequence in one pot with good yields and stereoselectivity. The structures and absolute configurations of the products were confirmed by X-ray analysis.
已开发出一种新方法,用于对映选择性合成具有高对映选择性(最高ee为96%)的高度官能化的环庚[ b ]吲哚。该方法在一锅中结合了对映选择性有机催化迈克尔加成反应和高效的双重Friedel-Crafts反应顺序,并具有良好的收率和立体选择性。通过X射线分析确认了产物的结构和绝对构型。
Highly selective γ-alkoxylation, γ-amination and γ-alkylation of unbiased enals by means of photoredox catalysis