Errika Voutyritsa

In recent years, Photoredox Catalysis has come to the forefront in Organic Chemistry, as a powerful strategy for the activation of small molecules. In general, most examples rely on the use of metal-based catalysts and organic dyes. Photo-organocatalysis is a low-cost and environmentally friendly alternative. We have recently developed a photoorganocatalytic protocol that is easy to operate, employing cheap household lamps, as the irradiation source and phenylglyoxylic acid, a cheap, organic, and commercially available molecule, as the catalyst. Our novel, mild, metal-free and easy-to-execute protocol, is succesfully employed in the functionalization of a wide range of C-H bonds leading to molecules with various potential applications in medicinal and bioorganic chemistry.(1) Specifically, an efficient visible-light hydroacylation of dialkyl azodicarboxylates, has developed. This methodology was extented in the synthesis of hydroxamic acids and amides and found application in the synthesis of the drugs Vorinostat and Moclobemide. A green and easy reproducible selective hydroacylation of alkenes has also presented. Phenylglyoxylic acid catalyses the synthesis of γ-lactones, starting from diesters of maleic acid and various primary and secondary alcohols. In all cases, phenylglyoxylic acid forms an exciplex with dialkyl maleate or azodicarboxylate through a photoinduced electron transfer (PET). When a HAT donor (aldehyde or alcohol) is present, a HAT process affords the initial acyl or hydroxyl radical.

References:
(1) a) G. N. Papadopoulos, D. Limnios, C. G. Kokotos, Chem. Eur. J. 2014, 20, 13811-13814; b) G. N. Papadopoulos, C. G. Kokotos, Chem. Eur. J. 2016, 22, 6964-6967; c) G. N. Papadopoulos, C. G. Kokotos, J. Org. Chem. 2016, 81, 7023-7038; d) D. Limnios, C. G. Kokotos, Adv. Synth. Catal. 2017, 359, 323-328; e) N. Kaplaneris, A. Bisticha, G. N. Papadopoulos, D. Limnios, C. G. Kokotos, Green Chem. 2017, 19, 4451-4456; f) G. N. Papadopoulos, E. Voutyritsa, N. Kaplaneris, C. G. Kokotos, Chem. Eur. J. 2018, 24, 1726-1731.