Iodine-Mediated Solvent-Controlled Selective Electrophilic Cyclization and Oxidative Esterification of <i>o</i>-Alkynyl Aldehydes: An Easy Access to Pyranoquinolines, Pyranoquinolinones, and Isocumarins
作者:Akhilesh K. Verma、Vineeta Rustagi、Trapti Aggarwal、Amit P. Singh
DOI:10.1021/jo101526b
日期:2010.11.19
provides pyrano[4,3-b]quinolines 4a−f, via formation of cyclic iodonium intermediate Q; however, using alcohols as a solvent as well as nucleophile, o-alkynyl esters 5a−y were obtained selectively in good to excellent yields via formation of hypoiodide intermediate R. Subsequently, o-alkynyl esters were converted in to pyranoquinolinones 6a−i and isocoumarin 6j by electrophilic iodocyclization. This
描述了碘在邻炔基醛的亲电碘环化中在不同溶剂中的化学选择性行为。与CH 2 Cl 2中的I 2与适当的亲核试剂反应生成邻炔基醛3a - t可以通过形成环碘鎓中间体Q生成吡喃并[4,3- b ]喹啉4a - f;但是,使用醇和亲核试剂作为溶剂,通过形成次碘化物中间体,选择性地以良好或优异的收率获得了邻炔基酯5a - y。[R 。随后,通过亲电碘环化将邻炔基酯转化为吡喃喹啉酮6a - i和异香豆素6j。这种发达的氧化酯化反应为从醛3n - p化学选择性合成酯5q - u而不氧化底物中存在的伯醇提供了新途径。