Oxidative Esterification, Thioesterification, and Amidation of Aldehydes by a Two-Component Organocatalyst System Using a Chiral N-Heterocyclic Carbene and Redox-Active Riboflavin
作者:Soichiro Iwahana、Hiroki Iida、Eiji Yashima
DOI:10.1002/chem.201100737
日期:2011.7.11
Flavin of the month! Triazolium‐derived N‐heterocyclic carbenes (NHCs) and a flavin catalyzed the oxidative esterification, thioesterification, and amidation of aldehydes with various alcohols, thiols, and amines, respectively, with O2 as the terminal oxidant (see scheme; R1=aryl; R2, R3=alkyl or aryl). By using a chiral NHC catalyst, the enantioselective acylation promoted the kinetic resolution of
本月的黄素!三唑鎓衍生的N-杂环卡宾(NHC)和黄素分别以O 2为末端氧化剂,催化醛与各种醇,硫醇和胺的氧化氧化酯化,硫代酯化和酰胺化反应(参见方案; R 1 =芳基; R 2,R 3=烷基或芳基)。通过使用手性NHC催化剂,对映选择性酰化促进了外消旋醇的动力学拆分和内消旋二醇的不对称化。
A Comparison of Monocyclic and Bicyclic Phospholanes as Acyl-Transfer Catalysts
作者:E. Vedejs、O. Daugulis、L. A. Harper、J. A. MacKay、D. R. Powell
DOI:10.1021/jo030007+
日期:2003.6.1
The synthesis and evaluation of chiralphosphines 11, 15a, 19a, 24a, and 28a as nucleophilic catalysts for anhydride activation and kinetic resolution of alcohols is described. The relative reactivity follows the order 11a > 11b > 15a > 1 in the monocyclic series, and 24a > 19a > 28ain the bicyclic series, with an overall rate advantage of ca. 2 orders of magnitude for the bicyclic phospholanes over
Synthesis and Reactivity of New Chiral Bicyclic Phospholanes as Acyl-Transfer Catalysts
作者:James A. MacKay、Edwin Vedejs
DOI:10.1021/jo0519155
日期:2006.1.1
Synthesis of chiral phosphines 1a, 14a, and 18a as nucleophilic catalysts for anhydride activation and kinetic resolution of alcohols is described. Radical cyclization of alkenylphosphines produced the phosphabicyclooctane (PBO) core of catalysts la and 14a, while 18a was made by quenching a metallocycle precursor with dichlorophenylphosphine. Catalysts la and 14a are less reactive, while 18a is comparable to the most reactive catalysts in the PBO family. The preferred ground-state geometries of phosphine-boranes were identified using computational methods, and were correlated with the catalytic reactivity of the corresponding free phosphines.