NaI/PPh3-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

Dan Liu; Yue Zhao; Frederic W Patureau

doi:10.3762/bjoc.19.5

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

Beilstein J Org Chem. 2023 Jan 16:19:57-65. doi: 10.3762/bjoc.19.5. eCollection 2023.

Authors

Dan Liu¹, Yue Zhao¹, Frederic W Patureau¹

Affiliation

¹ Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.

Abstract

A practical NaI/PPh₃-catalyzed decarboxylative radical cascade cyclization of N-arylacrylamides with redox-active esters is described, which is mediated by visible light irradiation. A wide range of substrates bearing different substituents and derived from ubiquitous carboxylic acids, including α-amino acids, were synthesized and examined under this very mild, efficient, and cost effective transition-metal-free synthetic method. These afforded various functionalized oxindoles featuring a C3 quaternary stereogenic center. Mechanistic experiments suggest a radical mechanism.

Keywords: decarboxylative cascade cyclization; iodide catalysis; metal-free photocatalysis; oxindole; phosphine catalysis.

Grants and funding

ERC project 716136: 2O2ACTIVATION is acknowledged for generous financial support. We are also thankful to the Chinese Scholarship Council (CSC) for financial support to Dan Liu (No. 202106230113), and Yue Zhao (No. 201908320377).