Rhodium(III)-catalyzed annulative coupling of sulfoxonium ylides with allenoates was achieved, forming highly functionalized cyclopropanes with a quaternary carbon center by means of the sulfoxonium ylide functionality as a traceless bifunctional directinggroup and C4 synthon via an arene C-H activation and cyclopropanation cascade. The protocol features simultaneous formation of three new C-C bonds
The Renaissance of an Old Problem: Highly Regioselective Carboxylation of 2-Alkynyl Bromides with Carbon Dioxide
作者:Bukeyan Miao、Gen Li、Shengming Ma
DOI:10.1002/chem.201503494
日期:2015.11.23
A steric effect‐controlled, zinc‐mediated carboxylation of different 2‐alkynyl bromides under an atmosphericpressure of CO2 has been developed by careful tuning of different reaction parameters, including the metal, solvent, temperature, and additive. 2‐Substituted 2,3‐allenoic acids were afforded from primary 2‐alkynyl bromides, whereas the carboxylation of secondary 2‐alkynyl bromides yielded 3‐alkynoic
Synthesis of Terminal Allenes through Copper-Mediated Cross-Coupling of Ethyne with<i>N</i>-Tosylhydrazones or α-Diazoesters
作者:Fei Ye、Chengpeng Wang、Xiaoshen Ma、Mohammad Lokman Hossain、Ying Xia、Yan Zhang、Jianbo Wang
DOI:10.1021/jo502316q
日期:2015.1.2
Ethyne is employed as coupling partner in copper-mediated cross-coupling reactions with N-tosylhydrazones and alpha-diazoacetate, leading to the development of a new synthetic method for terminal allenes. With this novel coupling method, the terminal allenes were obtained in good yields and with excellent functional group tolerance. Copper carbene migratory insertion is proposed as the key step in these transformations.
Amination, Aminocarbonylation, and Alkoxycarbonylation of Allenic/Propargylic Pd Intermediates Derived from Nonracemic Propargylic Mesylates: Synthesis of Nonracemic Propargyl Amines, Allenic Amides, and Butenolides