Abstract The ring-photoisomerization of 3-amino-and 3-methylamino-5-phenyl-1, 2, 4- oxadiazoles into the corresponding 2-amino-and 2-methylamino-5-phenyl-1, 3, 4- oxadiazoles has been reinvestigated by examining the effect of a base on the photoreaction. On irradiating at λ= 254 nm in methanol, yields of the ring-photoisomers were found to be significantly enhanced by the addition of triethylamine (TEA) in the photoreaction medium. ...
