Enantiospecific, Regioselective Cross-Coupling Reactions of Secondary Allylic Boronic Esters
作者:Laetitia Chausset-Boissarie、Kazem Ghozati、Emily LaBine、Jack L.-Y. Chen、Varinder K. Aggarwal、Cathleen M. Crudden
DOI:10.1002/chem.201303683
日期:2013.12.23
enantioselective Suzuki–Miyaura cross‐coupling of chiral, enantioenriched secondaryallylic boronic esters is described (see scheme; DME=dimethoxyethane, Bpin = pinacolboryl, dba = dibenzylideneacetone). Mechanistic studies show that the reactions proceed via γ‐selective transmetalation followed by reductive elimination. The reaction provides the first independent confirmation that the transmetalation of
Synthesis and deprotonation of 1-(p-toluenesulfonyl)-2-al-kenyl carbamates. Dichotomous achiral d1 and chiral d3 reagents for carbonyl addition directed by metal exchange
作者:Michael Reggelin、Petra Tebben、Dieter Hoppe
DOI:10.1016/s0040-4039(00)99157-3
日期:1989.1
title compounds 3 were prepared by electrophilic sulfonylation of allylic carbamates 1. The achiral lithium anions 4 add to carbonyl compounds with the α-position, thus permitting nucleophilic alkenoylation, whereas the chiral titanium derivates 8 undergo completely regioselective γ-addition, representing a new class of homoenolate reagents.
Sparteine complexes of lithiated primary O-2-alkenyl carbamates stereochemistry of the lithium-titanium exchange and application for the synthesis of enantiomerically enriched γ-lactones
作者:Oliver Zschage、Dieter Hoppe
DOI:10.1016/0040-4020(92)80016-9
日期:1992.7
(−)-sparteine complex from 1-lithio-2-butenyl N,N-diisopropylcarbamate has (S)-configuration at the metal bearing carbon atom, in contrary to our previous assumption. Transmetallation with titanium tetraisopropoxide and the carboxylation proceed with inversion. The addition of aldehydes occurs in a anti-SE′-process. The enantioselective synthesis of homoaldol adducts and some corresponding γ-lactones is reported
与我们先前的假设相反,由1-硫代-2-丁烯基N,N-二异丙基氨基甲酸酯优先形成的(-)-天冬氨酸络合物在带有金属的碳原子上具有(S)-构型。用四异丙氧基钛进行金属转移和羧化反应进行转化。在加入醛的发生在抗-S E' -Process。据报道,高聚物加合物和一些相应的γ-内酯的对映选择性合成。