Enantioselective, Intermolecular [π2+σ2] Photocycloaddition Reactions of 2(1H)-Quinolones and Bicyclo[1.1.0]butanes.

1-Substituted bicyclo[1.1.0]butanes add enantioselectively to 2(1H)-quinolones upon irradiation (λ = 366 nm) in the presence of a chiral complexing agent. A two-point hydrogen bond between the quinolone and the template is responsible for stereocontrol in the photocycloaddition reaction. The reaction leads to the formation of products with a chiral bicyclo[2.1.1]hexane skeleton in high enantiomeric excess (91-99% ee). The chiral template can be almost quantitatively (97%) recovered and used in another reaction. A triplet reaction pathway is likely, and sensitization is a suitable tool if the reaction is to be performed with visible light (λ = 420 nm).

Emerging Organometallic Methods for the Synthesis of C-Branched (Hetero)aryl, Alkenyl, and Alkyl Glycosides: C-H Functionalization and Dual Photoredox Approaches.

Transition-metal-catalyzed C-H functionalization and photoredox nickel dual catalysis have emerged as innovative and powerful avenues for the synthesis of C-branched glycosides. These two concepts have been recently established and provide efficient and mild methods for accessing a series of valuable complex C-branched glycosides of great interest. Herein, recent developments in the synthesis of C-branched aryl/alkenyl/alkyl glycosides through these two approaches are highlighted.

Access to C-aryl/alkenylglycosides by directed Pd-catalyzed C-H functionalisation of the anomeric position in glycal-type substrates.

Directed palladium-catalyzed C-H functionalisation of C2-amido glycals onto the anomeric position is described as a novel route to C-aryl/alkenylglycosides. An aminoquinoline-type directing group was used to successfully introduce diverse (hetero)aryl and alkenyl groups at position 1 of the sugar (20 examples). Its application to the synthesis of a dapagliflozin analogue is presented.

"CO" as a Carbon Bridge to Build Complex C2-Branched Glycosides Using a Palladium-Catalyzed Carbonylative Suzuki-Miyaura Reaction from 2-Iodoglycals.

Development of a palladium-catalyzed carbonylative Suzuki-Miyaura coupling reaction between 2-iodoglycal partners and diverse aryl- and alkenyl-boronic acids is presented, leading to original 2-ketoglycals. The newly formed carbonyl link could be exploited to access 2-aryl/alkenyl-methylene-α-glucopyranoside scaffolds via a three-step sequence including an indium-mediated Ferrier-type reaction.