4418-84-2Relevant articles and documents
Hydrogen peroxide based oxidation of hydrazines using HBr catalyst
Du, Wanting,Ma, Zichao,Shao, Liming,Wang, Jian
, (2021/11/18)
Azo compounds (RN = NR′) are an important class of organic molecules that find wide application in organic synthesis. Herein, we report an efficient, practical and metal-free oxidation of hydrazines (RNH-NHR’) to azo compounds using 5 mol% HBr and hydrogen peroxide as terminal oxidant. This new method has been demonstrated by 40 examples with excellent yields. In addition, we showcased two examples of the one-pot sequential reactions involving our hydrazine oxidation/hydrolysis/Heck reaction or Cu-catalyzed N-arylation with aryl boronic acid. The distinct advantages of this protocol include metal-free catalysis, waste prevention, and easy operation.
Substitution of a nitro group by diazonium salts in σH-Adducts of carbanions to mono-nitrobenzenes. Formation of substituted azobenzenes and indazoles
Wróbel, Zbigniew,Wilk, Bogdan,Kwast, Andrzej
, (2021/05/19)
σH-Adducts formed at low temperature from nitrobenzene derivatives and carbanions stabilized by cyano, alkoxycarbonyl or sulfonyl groups react with benzenediazonium salts as nucleophiles, forming a new C–N bond preferentially at carbon atom bearing the nitro group. The so-formed intermediates eliminate HNO2 molecule under action of base, yielding substituted azobenzenes. Adducts of secondary carbanions, stabilized by cyano or sulfonyl groups to the ortho positions of nitrobenzenes, cyclize in situ to substituted indazoles. Some ortho σH-adducts of 1-chloroethyl phenyl sulfone carbanion add diazonium cations at meta position to the nitro group. In this case, the subsequent elimination of HCl leads to azo compounds retaining the nitro group in its original position.
TEMPO catalyzed oxidative dehydrogenation of hydrazobenzenes to azobenzenes
Fan, Baomin,Laishram, Ronibala Devi,Li, Jiayan,Luo, Yang,Lv, Haiping,More, Sagar,Su, Zhimin,Xu, Dandan,Yang, Yong,Zhan, Yong
supporting information, p. 3471 - 3474 (2020/05/25)
A metal-free direct oxidative dehydrogenation approach for the synthesis of azobenzenes from hydrazobenzenes has been developed by using TEMPO as an organocatalyst for the first time. The reaction proceeded in open air under mild reaction conditions. A wide range of hydrazobenzenes readily undergo dehydrogenation to give the corresponding azobenzenes in excellent yields.