Reactions of thiiranes with NH-heterocycles 1. An investigation of the reaction of 2-chloromethylthiirane with 3,5-dibromo-4-nitropyrazole.

The reaction of 2-chloromethylthiirane with 3,5-dibromo-4-nitropyrazole in H2O and the aprotic solvent MeCN in the presence of bases was investigated. It was found that thiirane-thietane rearrangement occurs in an aqueous medium with the formation of 3,5-dibromo-4-nitro-1-(thietan-3-yl)-1H-pyrazole. In MeCN, 3,5-dibromo-4-nitro-1-(thiiran-2-ylmethyl)-1H-pyrazole and the product of its reaction with the starting pyrazole, 6-bromo-2-[(3,5-dibromo-4-nitro-1H-pyrazol-1-yl)methyl]-7-nitro-2,3-dihydropyrazolo[5,1-b]thiazole, are formed, the yields of which depend on the molar ratio of the reactants. [ABSTRACT FROM AUTHOR]