Base-induced cycloaddition of tosylmethyl or (tert-butoxycarbonyl)methyl isocyanide to 1,4-disubstituted 2,3-dinitro-1,3-butadienes. Access to 2,3-disubstituted 4-ethynylpyrroles
作者:Carlo Dell'Erba、Alessandro Giglio、Angelo Mugnoli、Marino Novi、Giovanni Petrillo、Paola Stagnaro
DOI:10.1016/0040-4020(95)98713-r
日期:1995.4
The reactions of 1,4-disubstituted 2,3-dinitro-1,3-butadienes 1a-g in THF with isocyanides XCH2NC (TosMIC, X = tosyl; TBICA, X = COOBut) and DBU furnish good to moderate yields of 2,3-disubstituted 4-ethynylpyrroles 5a-g or 6a-g. In the reaction of 1g with TosMIC and DBU the nitrovinyl pyrrole 7g and the 3,3′-dipyrrole 4g are also isolated as by-products. A mechanism involving sequential base-induced
1,4-二取代的2,3-二硝基-1,3-丁二烯1a-g在THF中与异氰酸酯XCH 2 NC(TosMIC,X =甲苯磺酰基; TBICA,X = COOBu t)和DBU的反应提供了良好至中等的收率2,3-二取代的4-乙炔基吡咯5a-g或6a-g。在1g与TosMIC和DBU的反应中,也分离出副产物硝基乙烯基吡咯7g和3,3'-二吡咯4g。提出了涉及顺序的碱基诱导的加成,消除和环化步骤的机制以说明分离产物的形成。