Nucleophilic aromatic substitutions on 4,5-dicyanopyridazine. Pyrrole and indole systems as carbon nucleophiles
作者:Marco Cecchi、Alessandra Micoli、Donatella Giomi
DOI:10.1016/j.tet.2006.10.007
日期:2006.12
5-Dicyanopyridazine was found to react with pyrrole and indole counterparts not only as heterocyclic azadiene in inverse electron-demand Hetero Diels–Alder reactions, as previously evidenced, but even as a very reactive heterocyclic electrophile at C-4 carbon, in formal SNAr2 processes where a CN group acts as leaving group. In particular, operating in acetic acid as solvent, nucleophilic addition–elimination sequences
如前所述,发现4,5-二氰基哒嗪与吡咯和吲哚对应物不仅在逆电子需求的杂狄尔斯-阿尔德反应中作为杂环氮杂二烯反应,而且甚至在C-4碳上作为非常活泼的杂环亲电试剂发生反应。CN基团充当离去基团的S N Ar2过程。尤其是,在乙酸作为溶剂的情况下,亲核加成-消除序列允许通过相应的1,4-二氢哒嗪加合物轻松获得吡咯基和吲哚基哒嗪。