Facile metal free regioselective transfer hydrogenation of polarized olefins with ammonia borane
作者:Xianghua Yang、Thomas Fox、Heinz Berke
DOI:10.1039/c0cc03163a
日期:——
Transfer hydrogenation of polarized olefins bearing strongly electron-withdrawing groups on one side of the double bond was achieved with ammonia borane under mild conditions without using a catalyst. Mechanistic studies proved the character of the direct H transfers proceeding stepwise with a unique hydroboration intermediate and hydride before proton transfer.
AlCl<sub>3</sub> catalyzed coupling of N-benzylic sulfonamides with 2-substituted cyanoacetates through carbon–nitrogen bond cleavage
作者:Chen Hu、Gang Hong、Xiaofei Qian、Kwang Rim Kim、Xiaoyan Zhu、Limin Wang
DOI:10.1039/c7ob01025g
日期:——
A new cross-coupling reaction of N-benzylic sulfonamides with 2-substituted cyanoacetates for the synthesis of 2-substituted benzylbenzene was reported. In the presence of the AlCl3, a broad range of N-benzylic sulfonamides reacted smoothly with 2-substituted cyanoacetates to afford structurally diverse benzylbenzenes in moderate to excellent yields. The conversion could be enlarged to gram-scale efficiently
Selective Benzylic and Allylic Alkylation of Protic Nucleophiles with Sulfonamides through Double Lewis Acid Catalyzed Cleavage of sp<sup>3</sup>Carbon-Nitrogen Bonds
broad range of tosyl‐activated benzylic and allylic amines to give diversely functionalized products in good to excellent yields and with high regioselectivity. Furthermore, the cross‐coupling reaction of 1,3‐dicarbonyl compounds with benzylic propargylicamine derivatives has been successfully applied to the one‐step synthesis of polysubstituted furans and benzofurans.
Polymer-Supported Hantzsch 1,4-Dihydropyridine Ester: An Efficient Biomimetic Hydrogen Source for the Reduction of Ketimines and Electron-Withdrawing Group Conjugated Olefins
作者:Jun Che、Yulin Lam
DOI:10.1002/adsc.201000093
日期:——
A polymer‐supported Hantzsch 1,4‐dihydropyridine ester was observed to be a useful selective reducing agent for the reduction of ketimines and electron‐withdrawing conjugatedolefins. The rate of the reduction of electron‐withdrawing conjugatedolefins is dependent on the nature of the conjugated substituents and could be enhanced by microwave irradiation. The reduction of (Z)‐α‐cyano‐β‐bromomethylcinnamates
of electron-deficient alkenes with disilanes in acetonitrile gave silylated alkanes in high yields. The photosilylation occurred in a highly regioselective manner at the position β to the electron-withdrawing groups of the alkenes. With asymmetrically substituted disilanes and polysilanes, silyl groups bearing more bulky substituents were preferentially introduced to the alkenes. The photoreactions were