Pd-Catalyzed Stereospecific and Ligand-Controlled Regiodivergent Suzuki-Miyaura Cross-Coupling for the Synthesis of 3-C-Glycals and 2,3-Unsaturated C-Glycosides.

The selective modification of carbohydrates to achieve structural complexity has emerged as a crucial strategy in carbohydrate-based drug development. However, the intricate stereochemistry and densely packed functional groups of carbohydrates pose significant challenges for precise stereoselectivity and regioselectivity control. Herein, we report a palladium-catalyzed, stereospecific, and ligand-controlled regiodivergent glycosyl Suzuki-Miyaura coupling of 3-boryl-glycals, establishing a robust platform for glycoside diversification with versatile C1 and C3 modification.

Palladium-catalyzed Suzuki-Miyaura cross-couplings of stable glycal boronates for robust synthesis of C-1 glycals.

C-1 Glycals serve as pivotal intermediates in synthesizing diverse C-glycosyl compounds and natural products, necessitating the development of concise, efficient and user-friendly methods to obtain C-1 glycosides is essential. The Suzuki-Miyaura cross-coupling of glycal boronates is notable for its reliability and non-toxic nature, but glycal donor stability remains a challenge. Herein, we achieve a significant breakthrough by developing stable glycal boronates, effectively overcoming the stability issue in glycal-based Suzuki-Miyaura coupling.

Stereoselective alkyl -glycosylation of glycosyl esters anomeric C-O bond homolysis: efficient access to -glycosyl amino acids and -glycosyl peptides.

-Glycosyl peptides possess excellent metabolic stability and therapeutic properties and thus play critical roles in biological studies as well as drug discoveries. However, the limited accessibility of -glycosyl amino acids has significantly hindered the broader research of their structural features and mode of action. Herein, for the first time we disclose a novel visible-light-driven radical conjugate addition of 1,4-dihydropyridine (DHP)-derived glycosyl esters with dehydroalanine derivatives, generating -glycosyl amino acids and -glycosyl peptides in good yields with excellent stereoselectivities.

Brønsted Acid Catalyzed Cyclization of Aminodiazoesters with Aldehydes to 3-Carboxylate--Heterocycles.

A Brønsted acid catalyzed cyclization of aminodiazoesters with aldehydes is described. This reaction features broad substrate generality and functional group compatibility, affording a wide range of 5-7-membered 3-carboxylate--heterocycles containing different functional groups. The title products are able to be further elaborated through simple functional group transformations to produce synthetically useful -heterocycles.

Lewis Acid Catalyzed Electrophilic Aminomethyloxygenative Cyclization of Alkynols with ,-Aminals.

Lewis acid enables the electrophilic carbooxygenative cyclization of alkynols with ,-aminals. The new process proceeds efficiently under very mild conditions via a pathway that is opposite to classical carbo-metalation. These reactions exhibit broad substrate generality and functional group compatibility, leading to a wide variety of 5-8-membered oxacycles bearing diverse functional groups.

Palladium-Catalyzed Hydrocarbonylative Cyclization Enabled by Formal Insertion of Aromatic C═N Bonds into Pd-Acyl Bonds.

An efficient new formal insertion strategy via combination of reductive elimination and oxidative addition sequence was reported, in which the transient -acyliminium ions formed via hydrocarbonylation function as key intermediates. This strategy has enabled a novel palladium-catalyzed hydrocarbonylative cyclization of azaarene-tethered alkenes or dienes via sequential insertion of a C═C bond, CO, and a C═N bond into palladium-hydride bonds. This method provides a new and highly efficient synthetic approach to quinolizinones and its derivatives with extended π-conjugated systems, possessing tunable emission wavelengths and good photoluminescence capabilities.