Exploring Photoredox\nCatalytic Reactions as an Entry to Glycosyl-α-amino Acids

The synthesis of glycosyl-α-amino acids presents\na significant challenge due to the need for precise glycosidic linkages\nconnecting carbohydrate moieties to amino acids while maintaining\nstereo- and regiochemical fidelity. Classical methods relying on ionic\nintermediates (2e<sup>–</sup>) often involve intricate synthetic\nprocedures, particularly when dealing with 2-<i>N</i>-acetamido-2-deoxyglycosides\nlinked to α-amino acidsa crucial class of glycoconjugates\nthat play important biological roles. Considering the growing prominence\nof photocatalysis, this study explores various photoredox catalytic\napproaches to achieving glycosylation reactions. Our focus lies on\nthe notoriously difficult case of 2-<i>N</i>-acetamido-2-deoxyglycosyl-α-amino\nacids, which could be obtained efficiently by two methodologies that\ninvolved, on the one hand, photoredox Giese reactions using a chiral\ndehydroalanine (Dha) as an electron density-deficient alkene in these\nradical 1,4-additions and, on the other hand, photoredox glycosylations\nusing selenoglycosides as glycosyl donors and hydroxyl groups of protected\namino acids as acceptors.