Wiley-VCH Verlag, ChemInform, 41(32), p. no-no, 2010
Elsevier, Tetrahedron, 27(57), p. 5865-5871
DOI: 10.1016/s0040-4020(01)00524-5
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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 254nm 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.