EDA photochemistry: Mechanistic investigations and future opportunities

Synthesis of Phenol–Pyridinium Salts Enabled by Tandem Electron Donor–Acceptor Complexation and Iridium Photocatalysis

“…Given the electronic bias of the reaction for electron-poor pyridines and electron-rich phenols, we conducted UV–vis analysis to investigate the potential formation of an EDA complex (Figure B). For a mixture of 2,4-dimethoxyphenol ( 2a ) and 4-trifluoromethylpyridine ( 1a ) in the presence of TFA, a distinctive bathochromic shift was observedindicative of the formation of an EDA complex, as highlighted by the green line .…”

Photoinduced Alkylation of Diazines with N-(Acyloxy)phthalimides in the Presence of Triethylamine

“…The quantum yield (Φ) of the photochemical reaction between 1 and 2 was determined to be 0.53, suggesting the involvement of productive propagative chain mechanisms alongside inefficient initiation by the photoexcitation of the weak EDA aggregate I . 41 42 Thus, the resulting alkyl radical III adds to pyrimidine 2 to form the adduct radical IV , which likely serves as an electron donor together with deprotonation to N -(acyloxy)phthalimide 1 . 43 This results in the liberation of product 3 , with concomitant regeneration of alkyl radical III to propagate the chain, facilitating the rapid alkylation.…”

A General Platform for Visible Light Sulfonylation Reactions Enabled by Catalytic Triarylamine EDA Complexes

“…For this reason, finding alternative greener synthetic paradigms has become a major goal in the field of photocatalysis. To this end, the use of electron donor–acceptor (EDA) complexesalso known as charge transfer (CT) complexeshas recently gained attention as a useful synthetic tool in organic chemistry. − These complexes form through the association of electron donors and acceptors, leading to a reduction in the HOMO–LUMO gap and the appearance of a new charge-transfer absorption band. Upon irradiation, these EDA complexes undergo single electron transfer (SET), generating a radical-cation/radical–anion pair capable of initiating further chemical transformations.…”