6533b7cffe1ef96bd1258588

RESEARCH PRODUCT

Fluorinated heterocyclic compounds. A photochemical synthesis of 3-amino-5-perfluoroaryl-1,2,4-oxadiazoles

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Abstract A photochemical methodology for the synthesis of 3-amino- (or 3- N -substituted amino) 5-pentafluorophenyl-1,2,4-oxadiazoles is reported. Irradiation of 3-pentafluorobenzoylamino-4-methyl-1,2,5-oxadiazole (Furazan) at 254 nm in methanol and in the presence of ammonia, primary or secondary aliphatic amines produces 3-amino-, 3-( N -alkylamino)-, 3-( N , N -dialkylamino)-5-pentafluorophenyl-1,2,4-oxadiazoles. The photoreaction follows the fragmentation pattern of the furazan ring with the extrusion of acetonitrile and the formation of a counterpart fragment which the nitrogen nucleophile will capture. Depending on the nature of the reagent, displacement of a fluoride anion at the C(5)-pentafluorophenyl moiety of the first-formed oxadiazoles by the nitrogen nucleophile and/or the solvent also takes place. By the same photochemical approach, the synthesis of the 3-methoxy-5-pentafluorophenyl-1,2,4-oxadiazole is also described.