four-stereogenic centered tetrahydroindolizine intermediates could be efficiently transferred into axially chirality in 3-arylindolizines and vicinal pyridyl and aryl substituted 1,5-diketones. In addition, densely functionalized cyclopropanes and bridgedcyclic compound were also discovered depended on the nature of the pyridinium ylides. Mechanism studies were involved to explain the stereochemistry during the
Highly enantioselective synthesis of γ-substituted butenolides via the vinylogous Mukaiyama–Michael reaction catalyzed by a chiral scandium(iii)–N,N′-dioxide complex
A highly efficient catalytic asymmetric vinylogous Mukaiyama–Michael reaction of the 2-silyloxyfuran with chalcone derivatives, catalyzed by a chiralN,N′-dioxide–scandium(III) complex, has been accomplished which tolerates a wide range of substrates. The reaction proceeds with complete regioselectivities, excellent diastereoselectivities (up to >99 : 1 dr) and good to excellent enantioselectivities
A base-controlled chemoselective transfer hydrogenation of α,β-unsaturated ketones catalyzed by [IrCp*Cl<sub>2</sub>]<sub>2</sub> with 2-propanol
作者:Shu-jie Chen、Guo-ping Lu、Chun Cai
DOI:10.1039/c5ra00484e
日期:——
A simple homogeneous catalyst system based on commercially available [IrCp*Cl2]2 has been developed for the transfer hydrogenation of α,β-unsaturated ketones.
The catalytic asymmetric aza-Michaelreaction of benzoyl hydrazine toward chalcones through the nonactivated amine moiety conjugated addition was facilitated by the developed N,N'-dioxide-Sc(OTf)(3) complex under mild conditions, affording the pharmacologically and synthetically useful products in moderate to high yields with up to 97% ee.
Dibrominated addition and substitution of alkenes catalyzed by Mn<sub>2</sub>(CO)<sub>10</sub>
作者:Xianheng Song、Shanshui Meng、Hong Zhang、Yi Jiang、Albert S. C. Chan、Yong Zou
DOI:10.1039/d1cc04534b
日期:——
A practical method for the dibromination of alkenes without using molecular bromine is consistently appealing in organic synthesis. Herein, we report Mn-catalyzed dibrominated addition and substitution of alkenes only with N-bromosuccinimide, producing a variety of synthetically valuable dibrominated compounds in moderate to high yields.