Divergent syntheses of iodinated isobenzofuranones and isochromenones by iodolactonization of 2-alkynylbenzoic acids in ionic liquids
作者:Raffaella Mancuso、Christian C. Pomelli、Francesco Malafronte、Asif Maner、Nadia Marino、Cinzia Chiappe、Bartolo Gabriele
DOI:10.1039/c7ob00962c
日期:——
2-alkynylbenzoic acids, carried out at 100 °C in ionic liquids (ILs) as unconventional solvents and with molecular iodine as the iodine source, in the absence of external bases, was found to be strongly dependent on the nature of the IL medium. In particular, while the use of N-ethyl-N-methylmorpholinium dicyanamide (Mor1,2N(CN)2) promoted the stereoselective formation of (E)-3-(iodomethylene)isobenzofuran-1(3H)-ones
发现在没有外部碱的情况下,于100°C在离子液体(ILs)中作为非常规溶剂并以分子碘作为碘源,在100°C下进行了2-炔基苯甲酸的碘内酯化的区域化学结果强烈依赖于IL介质的性质。特别是,虽然使用N-乙基-N-甲基吗啉二氰胺(Mor 1,2 N(CN)2)促进了(E)-3-(碘亚甲基)异苯并呋喃-1(3 H)-ones的立体选择性形成,通过反-5- exo-dig环化途径,使用1-乙基-3-甲基咪唑乙基硫酸乙酯(EmimEtSO 4)倾向于使用6-内切-环化模式,优先或选择性形成4-碘-1 H-异色素n-1-酮。无论如何,在用乙醚从反应混合物中萃取产物后,IL溶剂可以容易地再循环。已经进行了DFT计算以阐明IL的性质在偏爱反-5- exo-dig环化途径或6 -endo-dig模式中的作用。在2-乙炔基苯甲酸的碘环化的情况下,在EmimEtSO 4和Mor 1,2 N(CN)2溶剂中均仅观察到5-