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
Palladium on Charcoal as a Catalyst for Stoichiometric Chemo- and Stereoselective Hydrosilylations and Hydrogenations with Triethylsilane
作者:Sakari Tuokko、Petri M. Pihko
DOI:10.1021/op5003209
日期:2014.12.19
Stoichiometric quantities of triethylsilane in the presence of activated Pd/C as the catalyst can be used to effect chemo-, regio-, and stereoselective hydrosilylation and transfer hydrogenation reactions. α,β-Unsaturatedaldehydes and ketones are selectively hydrosilylated to give the corresponding enol silanes or transfer hydrogenated to give the saturated carbonyl compounds in the presence of other
N-Heterocyclic Carbene Catalyzed Umpolung of Michael Acceptors for Intermolecular Reactions
作者:Akkattu T. Biju、Mohan Padmanaban、Nathalie E. Wurz、Frank Glorius
DOI:10.1002/anie.201103555
日期:2011.8.29
leahciM! The N‐heterocyclic carbenecatalyzedumpolung of Michaelacceptors proceeds through the formation of a deoxy‐Breslow intermediate (see scheme; EWG=electron‐withdrawing group). This nucleophilic species can react with other Michaelacceptors in an intermolecular fashion, thereby resulting in the formation of homo‐ or heterodimeric olefins. This “Michaelumpolung” should become a valuable method
漏气!N杂环卡宾催化的Michael受体的化合物通过形成脱氧Breslow中间体进行(参见方案; EWG =吸电子基团)。这种亲核物质可以分子间方式与其他迈克尔受体反应,从而导致形成同二聚或异二聚烯烃。这种“ Michael umpolung”应该成为形成致密官能化烯烃的一种有价值的方法。
Catalytic Asymmetric Epoxidation of α-Branched Enals
作者:Olga Lifchits、Corinna M. Reisinger、Benjamin List
DOI:10.1021/ja1037935
日期:2010.8.4
An asymmetric catalytic epoxidation of alpha-branched, alpha,beta-unsaturated aldehydes is presented. A highly synergistic combination of a primary cinchona-based amine and a chiral phosphoric acid was found to promote the reaction with excellent enantiocontrol for alpha-monosubstituted and alpha,beta-disubstituted enals.
Palladium on Charcoal Catalyzed 3,4-Hydroperoxidation of α-Substituted Enals with Triethylsilane and Water
作者:Petri Pihko、Sakari Tuokko
DOI:10.1055/s-0035-1561633
日期:——
α-substituted acroleins with triethylsilane and water under Pd/C catalysis and aerobic conditions. The reaction is composed of a Pd/C-catalyzed conjugate reduction step and a hydroperoxidation step. The hydroperoxidation takes place via autoxidation of sufficiently stable enols formed in situ by transfer hydrogenation. Upon reduction, 2,2-disubstituted 1,2-diols are obtained directly from aldehydes.