A General Organocatalyst for Direct α-Functionalization of Aldehydes: Stereoselective C−C, C−N, C−F, C−Br, and C−S Bond-Forming Reactions. Scope and Mechanistic Insights
摘要:
The development of a general organocatalyst for the alpha-functionalization of aldehydes, via an enamine intermediate, is presented. Based on optically active alpha,alpha-diarylprolinol silyl ethers, the scope and applications of this catalyst for the stereogenic formation of C-C, C-N, C-F, C-Br, and C-S bonds are outlined. The reactions all proceed in good to high yields and with excellent enantioselectivities. Furthermore, we will present mechanistic insight into the reaction course applying nonlinear effect studies, kinetic resolution, and computational investigations leading to an understanding of the properties of the alpha,alpha-diarylprolinol silyl ether catalysts.
A direct asymmetric Mannich reaction using a novel axiallychiralamino trifluoromethanesulfonamide (S)-3 has been developed in highly anti-selective and enantioselective manners. Thus, in the presence of a catalytic amount of (S)-3, the reactionsbetweenaldehydes and the alpha-imino ester 4 proceed smoothly to give the functional beta-amino aldehydes with significantly higher anti/syn ratio and enantioselectivity
Direct organocatalytic asymmetric Mannich-type reactions in aqueous media: one-pot Mannich-allylation reactions
作者:Armando Córdova、Carlos F Barbas
DOI:10.1016/s0040-4039(03)00019-4
日期:2003.2
organocatalytic asymmetric Mannich-type reactions in aqueousmedia are demonstrated herein. l-Proline-catalyzed reactions in aqueousmedia to provide β-formyl substituted α-amino acid derivatives with excellent diastereoselectivities (dr up to 19:1, syn/anti) and high enantioselectivities (ee between 72 and >99%). These conditions provided for the development of novel one-potasymmetric syntheses of cyclic
Direct catalytic asymmetric anti-selective Mannich-type reactions
作者:Ismail Ibrahem、Armando Córdova
DOI:10.1039/b602221a
日期:——
The simple chiral pyrrolidine catalyzed asymmetric anti-selective Mannich-typereaction is presented; the reaction gives the corresponding amino acid derivatives with 10:1- >19:1 dr and 97-99% ee.
Monolithic Silica Support for Immobilized Catalysis in Continuous Flow
作者:M. Grace Russell、Cedrick Veryser、James F. Hunter、Rachel L. Beingessner、Timothy F. Jamison
DOI:10.1002/adsc.201901185
日期:2020.1.23
reactors featuring immobilized catalysts are well‐precedented in continuous flow synthesis but can suffer from adverse pressure drops during use due to their small pore sizes and/or structural changes. Herein, we overcome this challenge with the synthesis of a structurally robust silica‐based monolith featuring pore sizes on the millimeter scale. The 3‐dimensional solid support structure is constructed
Asymmetric anti-Mannich reactions in continuous flow
作者:Rafael Martín-Rapún、Sonia Sayalero、Miquel A. Pericàs
DOI:10.1039/c3gc41444b
日期:——
A polystyrene-supported, pyrrolidine-based catalyst depicting very high activity and excellent stereoselectivity in the anti-Mannich reaction of aldehydes and ketones has been developed. The very robust, immobilized catalyst has been successfully used in the implementation of a continuous flow process with short residence times (down to 6 min) for the production of highly enantioenriched anti-type Mannich adducts at the preparative scale.