Alkyne Insertion Enabled Vinyl to Acyl 1,5‐Palladium Migration: Rapid Access to Substituted 5‐Membered‐Dihydrobenzofurans and Indolines

• Published in: Angewandte Chemie 2023-04, Vol.135 (18), p.n/a
• Main Authors: Ding, Mingruo, Ou, Pengcheng, Li, Xuening, Yu, Yinghua, Niu, Mengmeng, Yang, Yongjian, Huang, Yewei, Wang, Zhi‐Xiang, Huang, Xueliang
• Format: Article
• Language: English
• Subjects: Alkynes; Amination; Catellani Reaction; Chemistry; C−H Activation; Functional Group Migration; Heterocyclic compounds; Hydrogen bonds; Mechanistic Investigation; Palladium
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202300703

“Through space” palladium/hydrogen shift is an efficient strategy to achieve selective functionalization of a specific remote C−H bond. Compared with relatively extensive exploited 1,4‐palladium migration process, the relevant 1,5‐Pd/H shift was far less investigated. We herein report a novel 1,5‐Pd/H shift pattern between a vinyl and an acyl group. Through the pattern, rapid access to 5‐membered‐dihydrobenzofuran and indoline derivatives has been achieved. Further studies have unveiled an unprecedented trifunctionalization (vinylation, alkynylation and amination) of a phenyl ring through 1,5‐palladium migration relayed decarbonylative Catellani type reaction. A series of mechanistic investigations and DFT calculations have provided insights into the reaction pathway. Notably, it was unveiled that the 1,5‐palladium migration in our case prefers a stepwise mechanism involving a PdIV intermediate. We herein report a novel 1,5‐palladium/hydrogen shift pattern between a vinyl and an acyl group, which provides a divergent access to substituted 5‐membered‐dihydrobenzofurans and indolines. Further studies unveiled a novel relayed decarbonylative Catellani‐type reaction. Mechanistic investigations including DFT calculations have shed light on the reaction pathway.