Palladium‐Catalyzed Stereoselective Intramolecular Heck Dearomative Silylation of Indoles

Abstract

A palladium‐catalyzed stereoselective intramolecular Heck dearomative of indoles with silyl termination has been developed. A type of tetracyclic indoline derivatives containing silicon were prepared, involving N‐(2‐bromobenzoyl)indoles and silylboronates. This protocol not only led to a broad substrate scope in acceptable yields but also could be scaled up to gram quantities as well as further synthetic transformation.

Recent Advances in the Synthesis of Indolines via Dearomative Annulation of N‐acylindoles

“…The products obtained in the reaction are valuable building frameworks which could participate in significant In 2022, the Liu and Xia group reported a novel and straightforward protocol for the construction of polycyclic indolines containing silicon in the presence of Pd(OAc) 2 (5 mol %), dpppe (10 mol %), K 2 CO 3 (2.0 equiv), in 1,2-dichloroethane at 80 °C for 12 h (Scheme 35). [38] This tandem protocol, which could be scaled up to gram, enabled access to tetracyclic indoline derivatives containing silicon in moderate to good yields. The reaction robustness was highlighted by the latestage CÀ O double bond reduction reaction.…”

Palladium-catalyzed intramolecular Heck dearomative gem-difluorovinylation of indoles

“…46–49 At present, the production of polycyclic indoline scaffolds has been established by palladium-catalyzed intramolecular Heck dearomatization of indoles (Scheme 1c). 50–68 On the one hand, 1,2-difunctionalization of indoles is achieved when the resulting benzyl-Pd species are captured with diverse nucleophiles that can effectively form various C–X (H, C, N, O, P, B, and Si) bonds. On the other hand, the reactions can be terminated by β-H elimination to construct CC double bonds.…”

“…48,60,64–66 However, limited precursors restrict the installation of functionalized CC double bonds. Inspired by our first attempt at dearomatization of indoles, 67 we present herein an innovative idea for synthesizing gem -difluoroalkenes from N -(2-bromobenzoyl)indoles and ClCF 2 COONa. Remarkably, it is the first report of dearomative gem -difluorovinylation.…”

Palladium-Catalyzed Intramolecular Heck Dearomative Alkenylation of Indoles with N-Tosylhydrazones

“…In 2019, a concise palladium-catalyzed three-component reaction for the straightforward and regioselective construction of a number of fused indoline esters and amides was disclosed by the Wu group employing DPPP as the ligand and alcohols and anilines as nucleophiles . Recently, Liu and co-workers reported a novel and highly efficient protocol for the generation of polycyclic indolines containing silicon employing Pd­(OAc) 2 as the catalyst and dpppe as the ligand in 1,2-dichloroethane under a nitrogen atmosphere . The formation of C–C, C–Si, and C–B bonds has already been described in the aforementioned literature.…”