Stereoselective Hydrosilylation of Enals and Enones Catalysed by Palladium Nanoparticles
作者:Meryem Benohoud、Sakari Tuokko、Petri M. Pihko
DOI:10.1002/chem.201100655
日期:2011.7.18
A highly versatile and efficient hydrosilylation method by palladium nanoparticle catalysis allows the direct and chemoselective synthesis of 1) enolsilanes of high isomeric purity, 2) saturated aldehydes or ketones, or 3) the corresponding saturated acetals from α,β‐unsaturated aldehydes or ketones. The choice of the product is determined by simply switching the solvent from THF to mixtures of THF/water
substrates in asymmetric epoxidation reactions. In this study, chiral primary amines are shown to catalyze the asymmetric epoxidation of α-substitutedacroleins, a versatile type of 1,1-disubstituted terminal alkene. Among various chiral primary amines explored, the chiral primary-tertiary vicinal diamine derived from trans-1,2-diphenylethane-1,2-diamine is identified as the optimal catalyst, which, in combination
Mukaiyama-Michael Reactions with<i>trans</i>-2,5-Diarylpyrrolidine Catalysts: Enantioselectivity Arises from Attractive Noncovalent Interactions, Not from Steric Hindrance
作者:Eeva K. Kemppainen、Gokarneswar Sahoo、Antti Piisola、Andrea Hamza、Bianka Kótai、Imre Pápai、Petri M. Pihko
DOI:10.1002/chem.201304240
日期:2014.5.12
the predicted and observed stereoselectivities. The analysis of intermolecular forces reveals that the enantioselectivity is mostly due to stabilizing noncovalentinteractions between the reacting partners, not due to sterichindrance. The role of attractivenoncovalentinteractions in enantioselective catalysis may be underappreciated.
A rapid and extremely convenient method for α-methylenation of aldehydes with aqueous formaldehyde is described. Two optimal catalytic systems are presented that allow short reaction times and afford the functionalized products in good to excellent yields (up to 99%) and chemoselectivity.
Sequential Asymmetric Catalysis in Michael–Michael–Michael–Aldol Reactions: Merging Organocatalysis with Photoredox Catalysis in a One-Pot Enantioselective Synthesis of Highly Functionalized Decalines Bearing a Quaternary Carbon Stereocenter
作者:Bor-Cherng Hong、Cheng-Wei Lin、Wei-Kai Liao、Gene-Hsiang Lee
DOI:10.1021/ol403113c
日期:2013.12.20
An expedited method has been developed for the enantioselectivesynthesis of highly functionalized decaline systems containing seven contiguous stereogenic centers with high enantioselectivities (>99% ee). The one-pot methodology comprises a cascade of organocatalytic double Michael–photocatalyzed Michael–aldol reactions of ethyl 2-bromo-6-formylhex-2-enoate, β-alkyl-α,β-unsaturated aldehydes, and