Pd-Catalyzed Synthesis of 1-(Hetero)aryl Thioglycosides: Strategy for the Trapping of an Acyl Group of Glycosylthioesters by Coupling of Bis-Electrophilic-Nucleophilic Partners.

Herein, we describe a stereoretentive palladium-catalyzed cross-coupling between the in situ-generated glycosyl thiolate anion and diverse (hetero)aryl iodides at room temperature for creating the library of (hetero)aryl thioglycosides. The key to success is the judicious pairing of bis-electrophilic-nucleophilic partners with a variety of thioesters in an atom-economical way in which both the glycosyl thiolate anion and the acylium cation are incorporated into the final analogue. The advantage of this method is the acyl transfer on various nucleophilic partners, including a hydroxyl, a primary or secondary amine, an amino acid, and the biologically active hSGLT1 inhibitor.

Atom-Economic Synthesis of Unsymmetrical -Diarylmethylthio/Seleno Glycosides via Base Mediated C(O)-S/Se Bond Cleavage and Acyl Transfer Approach of Glycosylthio/Selenoacetates.

Herein, we invented the CsCO-mediated atom economic method that streamlines the scission of the C(O)-S/Se bond involving the in situ generation of an anomeric thiolate/selenolate anion, which reacted with -QMs to yield novel unsymmetrical -diarylmethylthio/seleno glycosides while retaining the anomeric stereochemistry. Notably, the key features of this protocol involve unprecedented long-range acyl transfer (from S/Se to O), thus affording acylation of the final product which is not yet reported by classical methods. This straightforward protocol offers a mild, short reaction time, synthetically simple approach, and compatibility with 8 types of sugar along with phenylthio/benzylseleno esters.

4,5-Dioxo-imidazolinium Cation-Promoted α-Selective Dehydrative Glycosylation of 2-Deoxy- and 2,6-Dideoxy Sugars.

Herein, we report the great potential of the 4,5-dioxo-imidazolinium cation activation strategy for dehydrative glycosylation reactions employing the readily available and economical geminal dichloroimidazolidinediones (DCIDs) that promotes the glycosylation between 2-deoxy- and 2,6-dideoxy-sugar hemiacetals with various acceptors in good yields and high α-selectivity. This research not only provides a mild and efficient alternative approach for stereoselective dehydrative glycosylation but also extends the dichloroimidazolidinedione as a novel promoter in the field of glycoscience.

Recent advances in palladium-catalyzed C(sp)/C(sp)-H bond functionalizations: access to C-branched glycosides.

Over the recent decades, tremendous interest has developed in the transformation of complex substrates by C-H activation and functionalization. In particular, palladium-catalyzed directing and non-directing group-assisted C-H functionalization has emerged as a powerful avenue to access C-branched glycosides. Due to the extreme complexity, delicate functionalities, and high stability of C-H bonds, site-selective functionalization of carbohydrate under mild conditions is highly desirable.