Asymmetric Hydrogenation of Racemic Allylic Alcohols via an Isomerization–Dynamic Kinetic Resolution Cascade
作者:Kun Wang、Saisai Niu、Xin Guo、Weijun Tang、Dong Xue、Jianliang Xiao、Huaming Sun、Chao Wang
DOI:10.1021/acs.joc.1c02916
日期:2022.3.4
Prochiral racemic allylic alcohols are converted to enantioenriched chiral alcohols bearing adjacent stereocenters catalyzed by a diamine diphosphine Ru complex in the presence of tBuOK. The protocol features a broad substrate scope (56 examples) and high diastereo- and enantioselectivities (up to >99:1 dr, >99% ee) and could be applied to the synthesis of enantioenriched chromane and indane compounds
A direct conversion of α,β-unsaturated ketones to vinylcyclopropanes: new zirconium-mediated reaction
作者:Philippe Bertus、Vincent Gandon、Jan Szymoniak
DOI:10.1039/a908897k
日期:——
Various vinylcyclopropanes are synthesized from α,β-unsaturated ketones via a zirconium-mediated [1,2]-addition–deoxygenative cyclopropanation sequence; the latter step surprisingly proceeds under specific protic conditions.
It's a trap! Both epoxides and aziridines substituted by an aryl ketone can be reduced efficiently using visible‐light photoredox catalysts. The radicals generated were trapped by allyl sulfones, and formed α‐branched β‐hydroxy or amino derivatives with high diastereocontrol (see scheme; dtbbpy=4,4′‐di‐tert‐butyl‐2,2′‐bipyridine, ppy=2‐phenylpyridine).
The effective one-step synthesis of conjugated arylenimines from the corresponding α′-aryl-α,β-enones and amines is carried out in the presence of TiCl4. Although these adducts are air- and moisture-sensitive, they have thus been easily obtained with fair yields, while some other literature procedures were unsuccessful.