e.g. Filippa Pettersson or Cancer Res. 75(6) , 1102-12, (2015) or 10.1002/anie.201600521
The Journal of Organic Chemistry
Ring transformation of 1, 3, 4-oxadiazole to s-triazole-fused heterocycles. New synthetic route for thiazolo [2, 3-c]-s-triazole and 7H-s-triazolo [3, 4-b][1, 3, 4] thiadiazine
(4m), accompanied by a small amount of the hydrazide 9m on treatment with ammonium acetate in acetic acid. Similar treatment of ketones 2a and 2b afforded only the hydrazides 9a and 9b, respectively. Ketones 2a-n reacted with hydrazine hydrate in acetic acid to give 7H-s-triazolo [3, 4-b][1, 3, 4] thiadiazines 5a-n. However, ketones 2o-q, with substituents a to the carbonyl group, could not be converted to the corresponding fused-ring systems. ...