Rhodium-catalysed additive-free alkoxycarbonylation of indoles: 2,4,6-trimethylbenzoic acid-based carbonate anhydrides as a versatile alkoxycarboxyl source

Hirotsugu Suzuki; Yuki Ito; Kentaro Yabe; Yosuke Takemura; Takanori Matsuda

doi:10.1039/d4ob00205a

Rhodium-catalysed additive-free alkoxycarbonylation of indoles: 2,4,6-trimethylbenzoic acid-based carbonate anhydrides as a versatile alkoxycarboxyl source

Org Biomol Chem. 2024 Apr 24;22(16):3209-3214. doi: 10.1039/d4ob00205a.

Authors

Hirotsugu Suzuki¹, Yuki Ito², Kentaro Yabe², Yosuke Takemura², Takanori Matsuda²

Affiliations

¹ Tenure-Track Program for Innovative Research, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan. h-suzuki@u-fukui.ac.jp.
² Department of Applied Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan. mtd@rs.tus.ac.jp.

PMID: 38563730
DOI: 10.1039/d4ob00205a

Abstract

We report a CO-free approach to indole-2-carboxylic esters: rhodium-catalysed C(2)-alkoxycarbonylation of indoles with 2,4,6-trimethylbenzoic acid-based carbonate anhydrides. Selective C-O bond cleavage of the anhydrides facilitates the introduction of various alkoxycarbonyl groups. Control experiments suggest that merging a rhodium catalyst and KI promotes the in situ formation of the RhI species.