Visible‐Light‐Mediated Aerobic Tandem Dehydrogenative Povarov/Aromatization Reaction: Synthesis of Isocryptolepines
作者:Eva Schendera、Lisa‐Natascha Unkel、Phung Phan Huyen Quyen、Gwen Salkewitz、Frank Hoffmann、Alexander Villinger、Malte Brasholz
DOI:10.1002/chem.201903921
日期:2020.1.2
A metal-free, photoinduced aerobic tandem amine dehydrogenation/Povarov cyclization/aromatization reaction between N-aryl glycine esters and indoles leads to tetracyclic 11H-indolo[3,2-c]quinolines under mild conditions and with high yields. The reaction can be performed by using molecular iodine along with visible light, or by combining an organic photoredox catalyst with a halide anion. Mechanistic
N-芳基甘氨酸酯和吲哚之间的无金属光诱导的好氧串联胺脱氢/ Povarov环化/芳构化反应可在温和条件下以高收率生成四环11H-吲哚并[3,2-c]喹啉。该反应可以通过使用分子碘与可见光一起进行,或者通过将有机光氧化还原催化剂与卤化物阴离子结合来进行。机理研究表明,产物形成是通过自由基介导的氧化步骤与亚胺离子或N-卤代铵离子[4 + 2]-环加成反应而发生的,N杂环产物构成了抗疟原虫天然生物碱异cryptolepine的新类似物。