Improved Zinc-Catalyzed Simmons–Smith Reaction: Access to Various 1,2,3-Trisubstituted Cyclopropanes
作者:Éric Lévesque、Sébastien R. Goudreau、André B. Charette
DOI:10.1021/ol500267w
日期:2014.3.7
The Simmons–Smith reaction of zinccarbenoids with alkenes is a powerful method to access cyclopropanes containing various substitution patterns. This work exploits the high reactivity of aryldiazomethanes toward zinc halides to generate aryl-substituted carbenoids catalytically. These carbenoids are able to cyclopropanate various alkenes diastereoselectively, including unfunctionalized substrates
The Cinchona Primary Amine-Catalyzed Asymmetric Epoxidation and Hydroperoxidation of α,β-Unsaturated Carbonyl Compounds with Hydrogen Peroxide
作者:Olga Lifchits、Manuel Mahlau、Corinna M. Reisinger、Anna Lee、Christophe Farès、Iakov Polyak、Gopinadhanpillai Gopakumar、Walter Thiel、Benjamin List
DOI:10.1021/ja402058v
日期:2013.5.1
Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogenperoxide as the oxidant, we have developed highly enantioselective Weitz-Scheffer-type epoxidation and hydroperoxidation reactions of α,β-unsaturated carbonylcompounds (up to 99.5:0.5 er). In this article, we present our full studies on this family of reactions, employing acyclic enones, 5-15-membered cyclic enones, and
Cob(I)alamin als Katalysator. 6. Mitteilung [1]. Bildung und Fragmentierung von Alkylcobalaminen, ein Gleichgewichtsprozess zwischen nukleophiler Addition und reduktiver Fragmentierung
作者:Albert Fischli、Peter Michael Müller
DOI:10.1002/hlca.19800630225
日期:1980.3.5
Cob(I)alamin as Catalyst. 6. Communication [1]. Formation and Fragmentation of Alkylcobalamins: the Nucleophilic Addition – Reductive Fragmentation Equilibrium
Acyclic Stereoselection in the Ortho Ester Claisen Rearrangement
作者:G. William Daub、James P. Edwards、Carol R. Okada、Jana Westran Allen、Claudia Tata Maxey、Matthew S. Wells、Alexandra S. Goldstein、Michael J. Dibley、Clarence J. Wang、Daniel P. Ostercamp、Steven Chung、Paula Shanklin Cunningham、Martin A. Berliner
DOI:10.1021/jo9614250
日期:1997.4.1
The ortho ester Claisen rearrangement of trisubstituted allylicalcohols exhibits significant levels of diastereoselection. In E allylicalcohols, a 1,3-diaxial interaction develops in the chairlike transition state leading to the anti isomer, rendering the reaction syn selective by a factor of 3-5 to 1. In Zallylicalcohols, the 1,3-diaxial interaction develops in the transition state leading to
Insertions of Silylenes into Vinyl Epoxides: Diastereoselective Synthesis of Functionalized, Optically Active <i>trans</i>-Dioxasilacyclooctenes
作者:Michel Prévost、K. A. Woerpel
DOI:10.1021/ja906204a
日期:2009.10.14
communication describes a direct route to functionalized nonracemic trans-dioxasilacyclooctenes that involves stereoselective silylene insertions into vinyl epoxides to provide vinyl silaoxetane intermediates. These strained allylic silanes then undergo uncatalyzed allylation of aldehydes to afford trans-dioxasilacyclooctenes. Diastereoselective additions to these alkenes allow efficient transfer of planar