Hydrogen Peroxide Promoted Mizoroki–Heck Reactions of Phenyldiazenes with Acrylates, Acrylamides, and Styrenes
作者:Roman Lasch、Stefanie K. Fehler、Markus R. Heinrich
DOI:10.1021/acs.orglett.6b00449
日期:2016.4.1
generation of phenyldiazenes from azocarboxylates allowed clean and selective reactions with styrenes, acrylates, and acrylamides using palladium(II) acetate in the presence of silver(I) acetate or hydrogen peroxide as oxidant. Hydrogen peroxide was thereby shown to be a cheap and broadly applicable alternative for the established palladium–silver(I) system.
Synthesis of Hydrazines via Radical Generation and Addition of Azocarboxylic <i>tert</i>-Butyl Esters
作者:Chen-Hao Ru、Shi-Huan Guo、Gao-Fei Pan、Xue-Qing Zhu、Ya-Ru Gao、Yong-Qiang Wang
DOI:10.1021/acs.orglett.8b00448
日期:2018.4.6
A new chemistry of azo compounds that is a radical generation and addition in situ of azocarboxylic tert-butyl esters to synthesize hydrazines has been described. The protocol provides a novel strategy for the synthesis of various hydrazines. The advantages of the transformation include broad substrate scope, benign conditions, and convenient operation.
Cycloaddition reactions of glycine imine anions to phenylazocarboxylic esters – a new access to 1,3,5-trisubstituted 1,2,4-triazoles
作者:Roman Lasch、Markus R. Heinrich
DOI:10.1016/j.tet.2015.04.078
日期:2015.6
Phenylazocarboxylic tert-butyl esters have recently been shown to be highly versatile building blocks due to their ability to undergo nucleophilic aromatic substitutions under mild conditions, particularly well with [F-18]fluoride, and to act as precursors for aryl radicals. In this article, we now report first examples for cycloaddition reactions to phenylazocarboxylates. In a one-pot reaction with readily accessible glycine imines, a variety of highly substituted 1,2,4-triazoles could be obtained. (C) 2015 Elsevier Ltd. All rights reserved.
Zinc-Mediated Allylation and Benzylation of Phenylazocarboxylic Esters
作者:Roman Lasch、Markus R. Heinrich
DOI:10.1021/acs.joc.5b01978
日期:2015.10.16
Allylation and benzylation of phenylazocarboxylic tert-butyl esters have been achieved under Barbier-type reaction conditions and in very short reactions times using the corresponding allyl and benzyl bromides or iodides in combination with zinc powder. Whereas all reactions occurred exclusively at the beta-nitrogen atom of the azocarboxylic esters, the linkage of allyl units was shown to depend on the substitution pattern at the double bond of the allyl halide. The hydrazines obtained are useful precursors for indoles and indazoles.