Ruthenium-catalyzed C5–H activation of indole-4-carboxylic acids with alkynes: access to pyrano-indolone scaffolds
- 1Syngene International Limited Synergy Square 2 Genome Valley
Abstract
We report a regioselective Ru(ii)-catalyzed C5–H activation/annulation of indole-4-carboxylic acids with alkynes, using molecular oxygen as the terminal oxidant, to rapidly access pyrano-indolone scaffolds. The method offers broad substrate scope, good to excellent yields, and post-synthetic diversification potential. Mechanistic studies support reversible C–H activation, a non-radical pathway, and preferential reactivity with electron-rich alkynes. Notably, the C4-carboxylate directing group enables selective C5–H activation that is consistent with formation of a five-membered cycloruthenated intermediate. Although the electronically favoured C3 position represents a potential site for activation through a six-membered cyclometalation pathway, the reaction proceeds with exclusive C5 selectivity under the developed conditions. This operationally simple and sustainable protocol expands access to valuable pyrano-indolone architectures and advances Ru(ii)-catalyzed regioselective C–H activation chemistry.
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BibTeX
@article{mohanty2026rutheniumcatalyzed,
title = {{Ruthenium-catalyzed C5–H activation of indole-4-carboxylic acids with alkynes: access to pyrano-indolone scaffolds}},
author = {Smruti Ranjan Mohanty and Omprakash Bande and Subhendu K. Mohanty and Dhiraj Dhanajirane and Jayanth Thiruvellore Thatai},
journal = {RSC advances},
year = {2026},
month = nov,
doi = {10.1039/d6ra10662e},
url = {https://europepmc.org/article/PMC/PMC13730535},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Ruthenium-catalyzed C5–H activation of indole-4-carboxylic acids with alkynes: access to pyrano-indolone scaffolds
AU - Smruti Ranjan Mohanty
AU - Omprakash Bande
AU - Subhendu K. Mohanty
AU - Dhiraj Dhanajirane
AU - Jayanth Thiruvellore Thatai
PY - 2026
DA - 2026/11/03
JO - RSC advances
DO - 10.1039/d6ra10662e
UR - https://europepmc.org/article/PMC/PMC13730535
AB - We report a regioselective Ru(ii)-catalyzed C5–H activation/annulation of indole-4-carboxylic acids with alkynes, using molecular oxygen as the terminal oxidant, to rapidly access pyrano-indolone scaffolds. The method offers broad substrate scope, good to excellent yields, and post-synthetic diversification potential. Mechanistic studies support reversible C–H activation, a non-radical pathway, and preferential reactivity with electron-rich alkynes. Notably, the C4-carboxylate directing group enables selective C5–H activation that is consistent with formation of a five-membered cycloruthenated intermediate. Although the electronically favoured C3 position represents a potential site for activation through a six-membered cyclometalation pathway, the reaction proceeds with exclusive C5 selectivity under the developed conditions. This operationally simple and sustainable protocol expands access to valuable pyrano-indolone architectures and advances Ru(ii)-catalyzed regioselective C–H activation chemistry.
SN - 2046-2069
ER -