Superior Reactivity of Thiosemicarbazides in the Synthesis of 2-Amino-1,3,4-oxadiazoles
作者:Sarah J. Dolman、Francis Gosselin、Paul D. O'Shea、Ian W. Davies
DOI:10.1021/jo0618730
日期:2006.12.1
A facile and general protocol for the preparation of 2-amino-1,3,4- oxadiazoles is reported. This method relies on a tosyl chloride/pyridine-mediated cyclization of a thiosemicarbazide, which is readily prepared by acylation of a given hydrazide with the appropriate isothiocyanate. Cyclization of the thiosemicarbazide consistently outperforms the analogous semicarbazide cyclization under these conditions, for 18 distinct examples. Utilizing this protocol, we have prepared 5-alkyl- and 5-aryl-2-amino-1,3,4-oxadiazoles in 78-99% yield.
Tetrazoles: LV. Perparation of 2-anilino-5-aryl(hetaryl)-1,3,4-oxadiazoles from 5-substituted tetrazoles under microwave activation
作者:Yu. A. Efimova、G. G. Karabanovich、T. V. Artamonova、G. I. Koldobskii
DOI:10.1134/s1070428009080211
日期:2009.8
In reaction of 5-aryl(hetaryl)tetrazoles with phenyl isocyanate under the conditions of microwave activation the corresponding 2-anilino-5-aryl(hetaryl)-1,3,4-oxadiazoles formed in high yields. The application of the microwave activation fourfold reduced the reaction time.