Abnormal Diels–Alder Reaction of Oxazoles with 4-Phenyl-3<i>H</i>-1,2,4-triazole-3,5(4<i>H</i>)-dione and Diethyl Azodicarboxylate, and X-Ray Crystal Structure of an Adduct
作者:Toshikazu Ibata、Hiroyuki Suga、Yasushi Isogami、Hatsue Tamura、Xiaolan Shi
DOI:10.1246/bcsj.65.2998
日期:1992.11
The reaction of substituted oxazoles with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (PTAD) or diethyl azodicarboxylate gave the corresponding 1,2,4-triazoline derivatives through formal [3+2] cycloaddition accompanying ring opening of oxazoles. The molecular structure of an adduct of 5-methoxy-4-methyl-2-(p-tolyl)oxazole with PTAD was determined by means of X-ray crystallography.
Synthesis of 2,5-Dihydro-1,2,4-oxadiazoles through Formal [3 + 2] Cycloaddition of Oxazoles with Nitrosobenzene Derivatives
作者:Hiroyuki Suga、Xiaolan Shi、Toshikazu Ibata
DOI:10.1246/bcsj.71.1231
日期:1998.5
The reactions of substituted oxazoles with nitrosobenzene gave 2-phenyl-2,5-dihydro-1,2,4-oxadiazoles regioselectively through formal [3 + 2] cycloadditions proceeding via a ringopening of oxazoles by an attack of nitrosobenzene. The reactions with 1-chloro- and 1-methyl-4-nitrosobenzenes also produced the corresponding 2,5-dihydro-1,2,4-oxadiazoles regioselectivity.