Greener and rapid access to bio-active heterocycles: one-pot solvent-free synthesis of 1,3,4-oxadiazoles and 1,3,4-thiadiazoles
作者:Vivek Polshettiwar、Rajender S. Varma
DOI:10.1016/j.tetlet.2007.11.165
日期:2008.1
A novel one-pot solvent-free synthesis of 1,3,4-oxadiazoles and 1,3,4-thiadiazoles by condensation of acid hydrazide and triethyl orthoalkanates under microwave irradiations is reported. This green protocol was catalyzed efficiently by solid supported Nafion®NR50 and phosphorus pentasulfide in alumina (P4S10/Al2O3) with excellent yields.
The synthesis of bis(1,3,4-oxadiazol-2-yl-phenylmethyl) sulfides and other related 1,3,4-oxadiazoles from 1,1′-diphenylthiodiacetic acid dihydrazide and triethyl orthoesters
作者:Agnieszka Kudelko
DOI:10.1016/j.tet.2011.09.018
日期:2011.11
1′-diphenylthiodiacetic acid dihydrazide and triethyl orthoesters in the presence of catalytic amount of glacial acetic acid resulted in the formation of three heterocyclic products: the appropriate bis(1,3,4-oxadiazol-2-yl-phenylmethyl) sulfides, 2-benzyl-1,3,4-oxadiazoles and 2-benzoyl-1,3,4-oxadiazoles. The presence of the latter two compounds is connected with carbon–sulfur fission in the molecule
The present invention relates to compounds of the formula (I) and pharmaceutically acceptable salts and solvates thereof, wherein the substituents are defined herein, to compositions containing such compounds and to the uses of such compounds for the treatment of allergic and respiratory conditions.
Reactions of α-mercaptocarboxylic acid hydrazides with triethyl orthoesters: synthesis of 1,3,4-thiadiazin-5(6H)-ones and 1,3,4-oxadiazoles
作者:Agnieszka Kudelko
DOI:10.1016/j.tet.2012.02.071
日期:2012.5
Reactions of alpha-mercapto-beta-phenylpropionic and alpha-mercaptophenylacetic acid hydrazides with triethyl orthoesters were conducted under N-2 in glacial acetic acid and resulted in the formation of two groups of products, derivatives of 1,3,4-thiadiazin-5(6H)-ones and 2-(1-mercaptomethyl)-1,3,4-oxadiazoles. When conducting the same transformations on a-mercaptophenylacetic acid hydrazide in the presence of air, two different products from the 1,3,4-oxadiazole family, the appropriate bis(1,3,4-oxadiazol-2-ylphenylmethyl) disulfides and 2-benzy1-1,3,4-oxadiazoles, were formed with the liberation of free sulfur. The oxygenated bis(1,3,4-oxadiazol-2-yl-phenylmethyl) disulfides were reduced to the corresponding 2-(1-mercaptomethyl)-1,3,4-oxadiazoles with the use of zinc powder under mild conditions. (C) 2012 Elsevier Ltd. All rights reserved.