Direct C2-H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

Martina Mamone; Giuseppe Gentile; Jacopo Dosso; Maurizio Prato; Giacomo Filippini

doi:10.3762/bjoc.19.42

Direct C2-H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

Beilstein J Org Chem. 2023 Apr 27:19:575-581. doi: 10.3762/bjoc.19.42. eCollection 2023.

Authors

Martina Mamone¹, Giuseppe Gentile¹, Jacopo Dosso¹, Maurizio Prato^{1

2

3}, Giacomo Filippini¹

Affiliations

¹ Department of Chemical and Pharmaceutical Sciences, INSTM UdR Trieste, University of Trieste, via Licio Giorgieri 1, 34127 Trieste, Italy.
² Centre for Cooperative Research in Biomaterials (CIC BiomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo de Miramón 194, 20014, Donostia San Sebastián, Spain.
³ Basque Fdn Sci, Ikerbasque, 48013 Bilbao, Spain.

Abstract

A light-driven metal-free protocol for the synthesis of sulfone-containing indoles under mild conditions is reported. Specifically, the process is driven by the photochemical activity of halogen-bonded complexes formed upon complexation of a sacrificial donor, namely 1,4-diazabicyclo[2.2.2]octane (DABCO), with α-iodosulfones. The reaction provides a variety of densely functionalized products in good yields (up to 96% yield). Mechanistic investigations are reported. These studies provide convincing evidences for the photochemical formation of reactive open-shell species.

Keywords: EDA complex; alkylation; halogens; indoles; photochemistry.

Grants and funding

The authors gratefully acknowledge the University of Trieste, INSTM and the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency (Grant No. MDM-2017-0720). G.F. and J.D. kindly acknowledge FRA2022 funded by the University of Trieste. G.F kindly acknowledges Microgrants 2021 funded by Region FVG (LR 2/2011, ART. 4). J.D. kindly acknowledges the RTDa–PON “ricerca e innovazione” 2014–2020.