Borane-Catalyzed Direct Asymmetric Vinylogous Mannich Reactions of Acyclic α,β-Unsaturated Ketones
作者:Jun-Jie Tian、Ning Liu、Qi-Fei Liu、Wei Sun、Xiao-Chen Wang
DOI:10.1021/jacs.1c00006
日期:2021.3.3
Herein, we report that, by using chiral bicyclic bisborane catalysts, we have achieved the first highly regio-, diastereo-, and enantioselective direct asymmetric vinylogous Mannich reactions of acyclic α,β-unsaturatedketones. The strong Lewis acidity and steric bulk of the bisborane catalysts were essential for the observed high yields and selectivities.
The formal hydroacylation reaction of allenes has been developed employing carboxylic anhydrides as acyl sources and hydrosilanes as reducing reagents in the presence of a commercially available palladium complex as a catalyst. The reaction affords α,β-unsaturated ketones regio- and stereoselectively. The similar catalyst system is also effective for the reduction of carboxylic anhydrides to the corresponding
Synthesis of dihalohydrins and tri- and tetra-substituted olefins
申请人:Board of Regents, The University of Texas System
公开号:US20040143125A1
公开(公告)日:2004-07-22
A novel synthesis reaction for highly stereospecific tri- and tetra-substituted olefins is described. A single stereoisomer of stable &agr;-halo-&agr;,&bgr;-ester is produced in high yield by the reaction of aldehyde or ketone with a trihalogenated compound such as trichloroacetate in the presence of CrCl
2
in a solvent. By varying the amount of CrCl
2
used, the stable dihalohydrin intermediate may be obtained as well.
An iron‐catalyzed chemo‐ and diastereoselective reduction of α,β‐unsaturated ketones into the corresponding saturated ketones in mild reaction conditions is reported herein. DFT calculations and experimental work underline that transfer hydride reduction is a more facile process than hydrogenation, unveiling the fundamental role of the base.