Visible-light-mediated synthesis of non-anomeric S-aryl glycosides via a photoactive electron-donor-acceptor complex

Photocatalyst-free light-promoted carbohydrate synthesis and modification

Photoredox catalysis has recently emerged as a powerful approach for preparing oligosaccharides because it uses mild conditions, is compatible with partially or completely unprotected carbohydrate substrates, and exhibits impressive regio- and stereo-selectivity and high functional group tolerance. However, most catalytic photoredox reactions require an external photocatalyst (organic dye or expensive transition-metal complex) to deliver key glycosyl radicals. Several photocatalyst-free photocatalytic reactions that avoid the use of expensive metal salts or organic-dye additives have received significant attention. In this review, we highlight the most recent developments in photocatalyst-free light-promoted carbohydrate synthesis and modification, which is expected to inspire broad interest in further innovations in the green synthesis of saccharides.

Visible-light induced decarboxylative coupling of phenoxyacetic acid with disulfides: synthesis of α-arylthioanisole derivatives

Photoredox-catalyzed cross-coupling reaction is an efficient strategy for the construction of organic molecules. Herein, we developed a method to synthesize α-arylthioanisoles by constructing C-S bonds in the presence of a Ru-photoredox catalyst. Thus, a series of α-arylthioanisole compounds were efficiently obtained through decarboxylative cross-coupling under mild conditions. This protocol features high efficiency, broad substrate scope and good functional group tolerance.

Synthesis of Nonclassical Heteroaryl C-Glycosides via Decarboxylative C-H Glycosylation

A photoredox-promoted decarboxylative C-H glycosylation for the synthesis of nonclassical heteroaryl C-glycosides is reported. This methodology is characterized by an exceedingly simple reaction system, high diastereoselectivity, and good functional group tolerance. Moreover, the operational procedure is simple, and the gram-scale reaction highlights the practical applicability of this protocol.

Fe(III)-catalyzed stereoselective synthesis of deoxyglycosides using stable bifunctional deoxy-phenylpropiolate glycoside donors

Herein, we report a mild and economical route for the stereoselective synthesis of 2-deoxy and 2,6-dideoxyglycosides via FeCl3-catalyzed activation of bench stable deoxy-phenylpropiolate glycosyl donors (D-PPGs). Optimized reaction conditions work well under additive-free conditions to afford the corresponding 2-deoxy and 2,6-dideoxyglycosides in good yields with high α-anomeric selectivity by reacting with sugar and non-sugar-based acceptors. The optimized conditions were also extended for disarmed D-PPG donors. In addition, the developed strategy is amenable to high-scale-up synthesis.