Photoinduced molecular rearrangements. Some comments on the ring-photoisomerization of 1,2,4-oxadiazoles into 1,3,4-oxadiazoles
作者:Silvestre Buscemi、Andrea Pace、Nicolò Vivona、Tullio Caronna
DOI:10.1002/jhet.5570380340
日期:2001.5
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
已经将3-氨基-和3-甲基氨基-5-苯基-1,2,4-恶二唑的环光异构化为相应的2-氨基-和2-甲基氨基-5-苯基-1,3,4-恶二唑。通过研究碱对光反应的影响进行了重新研究。在甲醇中以λ= 254 nm进行辐照时,发现通过在光反应介质中添加三乙胺(TEA),可以显着提高环状光异构体的收率。相比之下,在含TEA的乙腈中辐照3-氨基-5-苯基恶二唑几乎可以将光完全还原为苯甲酰胍,而仅检测到百分之几的环状光异构体。此外,在含三乙胺的乙腈中the敏感的3-氨基-5-苯基恶二唑的光解也得到了苯甲酰基胍,但没有痕量的环状光异构体。