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EFFICIENT SYNTHESIS OF TRI- AND DIFLUOROACETYL HYDRAZIDES AS USEFUL BUILDING BLOCKS FOR NON-SYMMETRICALLY SUBSTITUTED, FLUOROALKYLATED 1,3,4-OXADIAZOLES

Grzegorz Mlostoń, Emilia A. Obijalska, Alicja Żurawik, Heinz Heimgartner
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Abstract


A convenient and efficient approach to 2-arylamino-5-fluoroalkyl-1,3,4-oxadiazoles has been established via heterocyclization of tri- and difluoroacetylated thiosemicarbazides using dicyclohexylcarbodiimide. A heterocyclization performed with selected thiosemicarbazides under basic conditions led to 4-aryl-5-fluoroalkyl-2,4-dihydro-3H-1,2,4-triazole-3-thiones in moderate yields. The starting fluoroacetylated thiosemicarbazides were prepared by fluoroacetylation of benzyloxycarbonyl-protected hydrazine with a corresponding anhydride, followed by hydrogenolytic deprotection and reaction with arylisothiocyanates. Fluoroacetylated semicarbazides were prepared similarly, but all attempts to achieve their heterocyclization were unsuccessful.

How to Cite
Mlostoń, G.; Obijalska, E.; Żurawik, A.; Heimgartner, H. Chem. Heterocycl. Compd. 2016, 52, 133. [Khim. Geterotsikl. Soedin. 2016, 52, 133.]

For this article in the English edition see DOI 10.1007/s10593-016-1845-3


Keywords


fluoroalkylated heterocycles; hydrazides; 1,3,4-oxadiazoles; protected hydrazines; 1,2,4-triazole-3-thiones; heterocyclization

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