Prolinamides of Aminouracils, Organocatalyst Modifiable by Complementary Modules
作者:Karen M. Ruíz-Pérez、Beatriz Quiroz-García、Marcos Hernández-Rodríguez
DOI:10.1002/ejoc.201800886
日期:2018.11.8
Prolinamide organocatalysts with aminouracils have the features of enhanced NH acidity, an additional hydrogen‐bond donor and the self‐assembly with complementary modules by Watson–Crick pairing. Each module affects the selectivity of the reaction and particularly 2,6‐diaminopyridine is beneficial to the selectivity in the reaction.
[reaction: see text] Readily tunable and bifunctional L-prolinamides as novel organocatalysts have been developed, and their catalytic activities were evaluated in the direct asymmetric Aldolreactions of various aromatic aldehydes and cyclohexanone. High isolated yields (up to 94%), enantioselectivities (up to 99% ee), and anti-diastereoselectivities (up to 99:1) were obtained under the optimal conditions
Highly efficient organocatalysts for the asymmetric aldol reaction
作者:C. G. Jacoby、P. H. V. Vontobel、M. F. Bach、P. H. Schneider
DOI:10.1039/c7nj04424k
日期:——
synthetic route. The highly efficient five step methodology did not require intermediary purification and provided the compounds in high yields. The catalysts were successfully applied in the asymmetric direct aldolreaction between aromatic aldehydes and cyclic ketones in aqueous media. Aldol adducts were obtained in high yields with perfect stereoselectivities (up to >99% e.e. and >19 : 1 d.r.).
Unprecedented bifunctional enamine–metal Lewisacidcatalysts have been developed. In this bifunctional catalytic system, a tridentateligand tethered with a chiral secondary amine was designed to solve the acid–base self-quenching problem leading to catalyst inactivation. This new bifunctional enamine–metal Lewisacidcatalyst was found to catalyze aldol reactions of ketones efficiently in high yields
Highly enantioselective aldol reactions using a tropos dibenz[c,e]azepine organocatalyst
作者:Barry Lygo、Christopher Davison、Timothy Evans、James A.R. Gilks、John Leonard、Claude-Eric Roy
DOI:10.1016/j.tet.2011.09.101
日期:2011.12
The four-step synthesis of a chiral primary tertiary diamine salt, possessing a tropos dibenz[c,e]azepine ring is described. It is shown that 3.5–5 mol % of this salt is capable of promoting highly enantioselective crossed-aldol reactions between cyclohexanone and a series of aromatic aldehydes. In all cases, the aldol reactions proceed with high diastereoselectivity for the anti-aldol product. The