Visible-Light-Mediated Alkylation of Thiophenols via Electron Donor–Acceptor Complexes Formed between Two Reactants

Abstract

A metal-free, photocatalyst-free, photochemical system was developed for the direct alkylation of thiophenols via electron donor− acceptor (EDA) complexes (K EDA = 145 M −1 ) between two reactants, Nhydroxyphthalimide esters as acceptors and thiophenol anions as donors, in the presence of a tertiary amine. The EDA complexes in the reaction system have a broad range of visible-light absorption (400−650 nm) and can trigger the reaction effectively under sunlight.

Transition-Metal-Free and Photocatalyst-Free Sulfenylation of Halopyrazolamines under Visible-Light Irradiation via Electron Donor–Acceptor Complexes

“…23 Hua Fu and Qin-Hua Song separately reported thioether formation using the EDA strategy by involving radical auxiliary of N-hydroxy phthalimide (NHPI) ester (Scheme 1b). 24,25 The presence of a halogen bond (represented as R-X......Y) is confirmed by compelling evidence demonstrating an attractive interaction between the electrophilic component, primarily derived from a halogen element, and the nucleophilic component, primarily derived from a base element, according to G. R. Desiraju et al R-X is the donor in this case, while Y is the acceptor. 26 On the other hand, synthetic approaches for pyrazole thioether involves harsh reaction conditions such as the stoichiometric amount of oxidant 27 , high temperature 28 and waste by-product formation.…”

Effective Formation of New C(sp2)−S Bonds via Photoactivation of Alkylamine‐based Electron Donor‐Acceptor Complexes

“…In spite of the efforts directed to investigate the fabrication of new CÀ S bonds, novel methodologies that implies the EDA complex photochemistry using visible light in the absence of both photoredox catalysts and transition metals remains still scarce (Scheme 1b). [13] Furthermore, the existing approaches rely on EDAs formed by π-π interactions between the donor and acceptor or a thiolate-anion-π interaction, as well as the often incorporation of both the donor and acceptor units in the product, which limit the structural diversity of the methods. To overcome some of the current limitations, we envisioned the use of simple tertiary alkylamines as donors for the formation of EDA complexes with (hetero)arylhalides towards C(sp 2 )-functionalization.…”

Sustainable Thioetherification via Electron Donor–Acceptor Photoactivation Using Thianthrenium Salts

“…reported different visible‐light‐assisted EDA complex methods to forge C(sp 3 )−S bonds readily. Akiyama and co‐workers designed a combined EDA complex and hydrogen atom transfer (HAT) system, [3b] while Song and co‐workers used various alkyl N ‐hydroxyphthalimide esters as electron‐acceptors [3c] . However, these reactions are air sensitive and/or proceed through C(sp 2 )−X reduction.…”