1,2,4-Oxadiazole 4-Oxides as Nitrones in 1,3-Dipolar Cycloaddition Reactions to Vinyl Ethers
作者:Paolo Quadrelli、Fabio Lunghi、Bruna Bovio、William Gautschi、Pierluigi Caramella
DOI:10.1002/ejoc.201101615
日期:2012.3
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。