Porphyrins as Photoredox Catalysts in Csp(2)-H Arylations: Batch and Continuous Flow Approaches

Author(s)

de Souza, Aline A. N. ^[1] ; Silva, Nathalia S. ^[1] ; Mueller, Andressa V. ^[2] ; Polo, Andre S. ^[2] ; Brocksom, Timothy J. ^{[2, 1]} ; de Oliveira, Kleber T. ^[1]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Quim, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210580 Santo Andre, SP - Brazil

• Document type: Journal article
• Source: Journal of Organic Chemistry; v. 83, n. 24, p. 15077-15086, DEC 21 2018.
• Web of Science Citations: 5

Abstract

We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different alpha-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra-(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron donor in the triplet excited state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. A two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive, and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts. (AU)

• FAPESP's process: 15/21110-4 - Exploiting Photocatalyzed Reactions Under Continuous Flow Conditions by using Porphyrinoid Systems: (C-FlowPhotoChem)
• Grantee: Kleber Thiago de Oliveira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/07276-1 - CEPOF - Optics and Photonic Research Center
• Grantee: Vanderlei Salvador Bagnato
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 18/00106-7 - Photocatalyzed Reactions by using porphyrins and continuous flow conditions: Arylations of heterocycles and activated olefins.
• Grantee: Kleber Thiago de Oliveira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/24020-9 - Evaluation of processes photoassisted by Ru(II) and Re(I) polypyridyl compounds
• Grantee: Andressa Vidal Muller
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 16/21993-6 - Evaluation of Ru(II) and Re(I) polypyridyl compounds on photoactive devices
• Grantee: André Sarto Polo
• Support Opportunities: Regular Research Grants