Regio- and enantioselective properties of the lipase-catalyzed irreversible transesterification of some 2-substituted-1,4-butanediols in organic solvents
摘要:
The regioselectivity of the Pseudomonas fluorescens (P. cepacia) lipase (PFL)-catalyzed irreversible transesterification of 2-substituted-1,4-butanediols 1a-3a has been studied and, in the case of 3a, it has been shown that (R)- and (S)-diols are acylated with opposite regioselectivity.
Enantioselective and Diastereoselective Conjugate Radical Additions to α-Arylidene Ketones and Lactones
作者:Changjia Zhao、Mukund Sibi
DOI:10.1055/s-0036-1590930
日期:2017.12
A highly stereoselective conjugate radicaladdition to arylidene ketones and lactones has been developed. The conjugate radicaladditionsusingchiral salen Lewis acids proceeds with up to 99:1 dr and 87% ee in good to excellent chemical yields.
已经开发了一种高度立体选择性的共轭自由基加成到亚芳基酮和内酯。使用手性萨伦路易斯酸的共轭自由基加成以高达 99:1 dr 和 87% ee 的良好化学产率进行。
Giving a Second Chance to Ir/Sulfoximine-Based Catalysts for the Asymmetric Hydrogenation of Olefins Containing Poorly Coordinative Groups
作者:Maria Biosca、Oscar Pàmies、Montserrat Diéguez
DOI:10.1021/acs.joc.9b00829
日期:2019.6.21
This work identifies a family of Ir/phosphite-sulfoximine catalysts that has been successfully used in the asymmetrichydrogenation of olefins with poorly coordinative or noncoordinative groups. In comparison with analogue Ir/phosphine-sulfoximine catalysts previously reported, the presence of a phosphite group extended the range of olefins than can be efficiently hydrogenated. High enantioselectivities
This Letter describes a versatile synthetic approach to prepare physovenine and physostigmine analogs. A series of analogs were synthesized and evaluated for cholinesterase inhibition activities, including human acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) from human serum.
Alternatives to Phosphinooxazoline (<i>t-</i>
BuPHOX) Ligands in the Metal-Catalyzed Hydrogenation of Minimally Functionalized Olefins and Cyclic β-Enamides
privileged 4‐alkyl‐2‐[2‐(diphenylphosphino)phenyl]‐2‐oxazoline (PHOX) ligands by replacing the phosphine moiety by a biaryl phosphite group and/or the introduction of a methylene spacer between the oxazoline and the phenyl ring. The modular design of the ligands has given us the opportunity not only to overcome the limitations of the iridium‐PHOX catalytic systems in the hydrogenation of minimally functionalized