in a stereoselective manner. The reaction proceeds through generation of an α‐imino rhodium carbene complex, nucleophilic addition of the sulfur atom of a thioester onto the carbenoid carbonatom, and subsequent intramolecular migration of the acyl groupfrom the sulfur atom to the imino nitrogen atom. The method is successfully applied to a ring‐expansion reaction of thiolactones, thus leading to
A sequential procedure for the synthesis of 2,5-disubstituted thiazoles from terminal alkynes, sulfonyl azides, and thionoesters is reported. A copper(I)-catalyzed 1,3-dipolar cycloaddition of terminal alkynes with sulfonyl azides affords 1-sulfonyl-1,2,3-triazoles, which then react with thionoesters in the presence of a rhodium(II) catalyst. The resulting 3-sulfonyl-4-thiazolines subsequently aromatize
Cu2O acting as a robust catalyst in CuAAC reactions: water is the required medium
作者:Kai Wang、Xihe Bi、Shuangxi Xing、Peiqiu Liao、Zhongxue Fang、Xianyu Meng、Qian Zhang、Qun Liu、Yu Ji
DOI:10.1039/c0gc00848f
日期:——
Cu2O as the catalyst in water was found to be quite robust for the azide-alkyne cycloaddition (AAC) reaction, which was verified by a wide variety of applicable azides and alkynes. Water was proved to play an essential role because of a significant rate acceleration compared with reactions using organic solvents and conducted under neat conditions. The high catalytic performance of Cu2O/H2O system was further argued by decreasing the catalyst loading to ppm levels.
A new procedure for the stereoselective synthesis of syn alpha-amino beta-oxy ketones is reported. It consists of two steps; in the first step, alpha-amino silyl enol ethers having a (Z) geometry are prepared from 1-alkynes via 1-sulfonyl-1,2,3-triazoles. In the second step, the silyl enol ethers undergo the TiCl4-mediated Mukaiyama aldolreaction with aldehydes to produce alpha-amino beta-oxy ketones
insertion/asymmetric Claisen rearrangement tandem reaction of N‐sulfonyl‐1,2,3‐triazoles with allyl alcohol esters was achieved by bimetallic relay catalytic systems involving achiral rhodium salt and chiral N,N′‐dioxide–indium(III) complex. This manifold could overcome the limitation of single RhII catalysis, providing a straight and facileroute to various enantioenriched β/γ‐amino acid derivatives