A novel annulation reaction of N-(het)aroyldiazenes and isothiocyanates has been established. This transformation involves a sequential cyclization and desulfurization/intramolecular rearrangement to produce 2-imino-1,3,4-oxadiazolines. The less-stable N-(het)aroyldiazenes can be conveniently generated in situ by I2-mediated oxidation of hydrazides, which allows a one-pot synthesis of the products
Synthesis of 2-Imino-1,3,4-thiadiazoles from Hydrazides and Isothiocyanates via Sequential Oxidation and P(NMe<sub>2</sub>)<sub>3</sub>-Mediated Annulation Reactions
N-acyldiazenes with isothiocyanates, producing 2-imino-1,3,4-thiadiazoles, is reported. This reaction proceeds well with crude N-acyldiazenes derived from the oxidation of hydrazides by iodine and permits the sequential synthesis of products directly from hydrazides without purification of the less stable N-acyldiazene intermediates. The reaction does not require transition metals and is a simple, scalable operation
1,3-Diarylcycloalkanopyrazoles and diphenyl hydrazides as selective inhibitors of cyclooxygenase-2
作者:Zhihua Sui、Jihua Guan、Michael P. Ferro、Kathy McCoy、Michael P. Wachter、William V. Murray、Monica Singer、Michele Steber、Dave M. Ritchie、Dennis C. Argentieri
DOI:10.1016/s0960-894x(00)00041-x
日期:2000.3
cyclooxygenase-2. The 1,3-diaryl substitution pattern of the pyrazole ring in 1 differentiates these compounds from most of the known selective COX-2 inhibitors that contain two aryl rings at the adjacent positions on a heterocyclic or a phenylring. Similarly, the two phenylrings in 2 are also separated by three atoms. SAR of both phenylrings in 1 and 2, and the aliphatic ring in 1 will be discussed.
KOt-Bu promoted homocoupling and decomposition of N′-aryl acylhydrazines: synthesis of unsymmetric N′,N′-diaryl acylhydrazines
作者:Wei-juan Wang、Ting Zhang、Li-jun Duan、Xue-jing Zhang、Ming Yan
DOI:10.1016/j.tet.2015.10.023
日期:2015.12
The KOt-Bu promoted homocoupling and decomposition of N′-aryl acylhydrazines has been achieved. The method allows for a novel and efficient synthesis of unsymmetric N′,N′-diaryl acylhydrazines under mild reaction conditions. The reaction probably proceeds via the generation of N′-centered acylhydrazine radicals and the subsequent homolytic aromatic substitution.
[3 + 2]-Cycloaddition of <i>in Situ</i> Generated Nitrile Imines and Acetylene for Assembling of 1,3-Disubstituted Pyrazoles with Quantitative Deuterium Labeling
作者:Vladimir V. Voronin、Maria S. Ledovskaya、Evgeniy G. Gordeev、Konstantin S. Rodygin、Valentine P. Ananikov
DOI:10.1021/acs.joc.8b00155
日期:2018.4.6
methodology for the preparation of 1,3-disubstituted pyrazoles from in situ generated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base. The other part is used to generate acetylenefrom CaC2 and water. Partitioning of the reactants improves