Graduate School of Science, Nagoya University , Chikusa, Nagoya 464-8602, Japan.
JST-ERATO, Itami Molecular Nanocarbon Project, Nagoya University , Chikusa, Nagoya 464-8602, Japan.
Org Lett. 2017 Apr 7;19(7):1930-1933. doi: 10.1021/acs.orglett.7b00684. Epub 2017 Mar 30.
Annulative π-extension (APEX) reactions of heteroarenes are described herein. A catalytic system comprising a cationic palladium species and o-chloranil using dimethyldibenzosiloles as π-extending agents enabled the extension of the π-system of benzo[b]thiophenes. π-Extended dibenzofurans and carbazoles could also be obtained from benzofuran and N-tosylindole, respectively, with dimethyldibenzogermole as a germanium-based π-extending agent. Mechanistic investigations indicated two possible reaction pathways involving carbopalladation-based double C-H arylation of benzothiophene or formal cycloaddition/oxidation cascades.
本文描述了杂芳环的成环 π-扩展 (APEX) 反应。一个包含阳离子钯物种和邻氯醌的催化体系，使用二甲基二苯并硅烷作为π-扩展试剂，使得苯并[b]噻吩的π-体系得以扩展。使用二甲基二苯并锗烷作为锗基π-扩展试剂，还可以分别从苯并呋喃和 N-甲苯吲哚中得到扩展的二苯并呋喃和咔唑。机理研究表明，可能存在两种反应途径，涉及苯并噻吩的碳钯化双 C-H 芳基化或形式的环加成/氧化级联。
