Abstract
2,5-dimethyl-1,3,4-thiadiazole 1 reacts at low temperature sequentially with lithium diisopropylamide and carbonyl derivatives 2 to prepare, according to the ratio of reagents, either 2-methyl-5-[2-hydroxy-2-arylethyl (or alkyl)]-l,3,4-thiadiazoles 2 or 2,5-bis[2-hydroxy-2-arylethyl (or alkyl)]-l,3,4-thiadiazoles 4.