吲哚试验
戒指(化学)
噻吩
双环分子
化学
自由基离子
催化作用
光化学
基质(水族馆)
药物化学
立体化学
有机化学
离子
海洋学
地质学
作者
Alexandre Leclair,Qian Wang,Jieping Zhu
标识
DOI:10.1021/acscatal.1c05621
摘要
A single-electron transfer (SET) oxidation of indole or benzo[b]thiophene to a radical cation reverses the intrinsic polarity of these π-excessive bicyclic heteroarenes. Here we report an oxidative two-carbon homologation of cyclobutanols to cyclohexenones under a visible-light photoredox catalysis. 1-(Indol-2-yl)cyclobutan-1-ols are converted to 2,3,4,9-tetrahydro-1H-carbazol-1-ones, important structural motifs found in alkaloids and pharmaceuticals, with a broad substrate scope. A mechanistic study suggests that the reaction is initiated by an SET from an indole to an excited acridinium salt to generate the radical cation, which is followed by two consecutive 1,2-alkyl migrations and a rearomatization. Benzo[b]thiophene-substituted cyclobutanols are similarly converted to 2,3-dihydrodibenzo[b,d]thiophen-4(1H)-ones. A total synthesis of (±)-uleine featuring this ring-expansion process is documented.
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