conditions to yield oxadiazolinic esters. The structures of the adducts have been confirmed by X-ray structures and spectroscopic data. A donor p-methoxyphenyl at the nitronic carbon slows down the cycloaddition rate, while an acceptor p-nitrophenyl retards the rearrangement of the exo adduct.
1,2,4-恶二唑 4-氧化物显示出与 N-甲基-C-苯基硝酮相同的硝基反应性和选择性,N-甲基-C-苯基硝酮是一种典型的无环硝酮,可提供相当数量的内-和外-5-烷氧基异恶唑烷。外型立体异构体在反应条件下容易发生重排,生成恶二唑啉酯。加合物的结构已通过 X 射线结构和光谱数据得到证实。硝基碳上的供体对甲氧基苯基会减慢环加成速率,而受体对硝基苯基会阻止外加合物的重排。
A photochemical generation of nitrosocarbonyl intermediates
作者:P. Quadrelli、M. Mella、P. Caramella
DOI:10.1016/s0040-4039(98)02416-2
日期:1999.1
Nitroscarbonyl intermediates are photochemically generated from 1,2,4-oxadiazole-4-oxides and efficiently trapped with enes and dienes.
A thermal fragmentation of 1,2,4-oxadiazole-4-oxides to nitriles and nitrosocarbonyls
作者:P Quadrelli、G Campari、M Mella、P Caramella
DOI:10.1016/s0040-4039(00)00093-9
日期:2000.3
1,2,4-Oxadiazole-4-oxides undergo clean thermal cleavage in refluxing chlorobenzene or xylene to nitriles and nitrosocarbonyl intermediates, which are either trapped with suitable olefins to afford ene adducts or dimerize and rearrange to anhydrides.