Direct, Mild, and General <i>n</i>-Bu<sub>4</sub>NBr-Catalyzed Aldehyde Allylsilylation with Allyl Chlorides
作者:Makeda A. Tekle-Smith、Kevin S. Williamson、Isaac F. Hughes、James L. Leighton
DOI:10.1021/acs.orglett.7b03193
日期:2017.11.3
A direct, mild, and general method for the enantioselective allylsilylation of aldehydes with allyl chlorides is reported. The reactions are effectively catalyzed by 5 mol % of n-Bu4NBr, and this rate acceleration allows the use of complex allyl donors in fragment-coupling reactions and of electron-deficient allyl donors. The results are (1) significant progress toward a “universal” asymmetric aldehyde
Umpolung of Michael Acceptors Catalyzed by <i>N</i>-Heterocyclic Carbenes
作者:Christian Fischer、Sean W. Smith、David A. Powell、Gregory C. Fu
DOI:10.1021/ja058222q
日期:2006.2.1
N-Heterocycliccarbenes can catalyze beta-alkylations of a range of alpha,beta-unsaturated esters, amides, and nitriles that bear pendant leaving groups to form a variety of ring sizes. In this process, the nucleophilic catalyst transiently transforms the normally electrophilic beta carbon into a nucleophilic site through an unanticipated addition-tautomerization sequence.
Highly Enantioselective Synthesis of 1,2,3-Substituted Cyclopropanes by Using α-Iodo- and α-Chloromethylzinc Carbenoids
作者:Louis-Philippe B. Beaulieu、Lucie E. Zimmer、Alexandre Gagnon、André B. Charette
DOI:10.1002/chem.201202528
日期:2012.11.12
α‐chlorozinc carbenoids by using a dioxaborolane‐derived chiral ligand. The synthetically useful iodocyclopropane building blocks were derivatized by an electrophilic trapping of the corresponding cyclopropyl lithium species or a Negishi coupling to give access to a variety of enantioenriched 1,2,3‐substituted cyclopropanes. The synthetic utility of this method was demonstrated by the formal synthesis of an
Enantio- and Diastereoselective Iodocyclopropanation of Allylic Alcohols by Using a Substituted Zinc Carbenoid
作者:Louis-Philippe B. Beaulieu、Lucie E. Zimmer、André B. Charette
DOI:10.1002/chem.200902228
日期:2009.11.9
(Zinc)redible! 2,3‐Disubstituted and 2,3‐trisubstituted iodocyclopropanes can be accessed in enantiomerically enriched form by using the enantioselective Simmons–Smith iodocyclopropanation of allylicalcohols in the presence of the stoichiometric dioxaborolane chiral ligand. These iodocyclopropanes serve as versatile chiral building blocks towards highly functionalized 1,2,3‐trisubstituted cyclopropanes
<i>N</i>-(4-methylbenzenesulfonyl)- pyrrolidines and piperidines by a tandem S<sub>N</sub>2-michael addition reaction
作者:Richard A. Bunce、Jeffrey C. Allison
DOI:10.1080/00397919908086214
日期:1999.6
A tandem S(N)2-Michael addition sequence has been developed for the preparation of N-(4-methylbenzenesulfonyl)- pyrrolidines and piperidines bearing functionalized side chains at C-2.