Highly Enantioselective Epoxidation of α,β-Unsaturated Ketones Catalyzed by Rare-Earth Amides [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 with Phenoxy-Functionalized Chiral Prolinols
摘要:
A simple and efficient catalytic enantioselective epoxidation of alpha,beta-unsaturated ketones has been successfully developed, which was catalyzed by rare-earth metal amides [(Me3Si)(2)N](3)RE(mu-Cl)Li(THF)(3) (RE = Yb (1), La (2), Sm (3), Y (4), Lu (5)) in the presence of phenoxy-functionalized chiral prolinols at room temperature using tert-butylhydroperoxide (TBHP) as the oxidant. The combination of an Yb-based amide 1 and a chiral proligand (S)-2,4-di-tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol) performed very well, and both the yields and the enantiomeric excess of the chiral epoxides reached up to 99% and 99% ee.
Cascade Trisulfur Radical Anion (S<sub>3</sub><sup>•–</sup>) Addition/Electron Detosylation Process for the Synthesis of 1,2,3-Thiadiazoles and Isothiazoles
作者:Bei-Bei Liu、Hui-Wen Bai、Huan Liu、Shun-Yi Wang、Shun-Jun Ji
DOI:10.1021/acs.joc.8b01450
日期:2018.9.7
Trisulfur radical anion (S3•–) mediated reactions with in situ formed azoalkenes and α,β-usaturated N-sulfonylimines for the construction of 1,2,3-thiadiazoles and isothiazoles has been developed. S3•– is in situ generated from potassium sulfide in DMF. These two approaches provide a new, safe, and simple way to construct 4-subsituted 1,2,3-thiadiazoles, 5-subsituted 1,2,3-thiadiazoles, and isothiazole