Synthesis of diverse N-acyl-pyrazoles via cyclocondensation of hydrazides with α-oxeketene dithioacetal.

An elegant, efficient, and highly regioselective approach for the synthesis of novel methyl 5-amino-3-(methylthio)-1-differently substituted-1H-pyrazole-4-carboxylates is reported. The procedure involves the cyclocondensation of α-oxeketene S, S-dimethyl acetal building blocks with different alkyl, aryl, and heterocyclic acid hydrazides. The novel molecules were obtained in good yields and their identities confirmed by NMR and HRMS spectrometry.