Chemical approaches for the stereocontrolled synthesis of 1,2-cis-ß-D-rhamnosides.

In carbohydrate chemistry, the stereoselective synthesis of 1,2-cis-glycosides remains a formidable challenge. This complexity is comparable to the synthesis of 1,2-cis-ß-D-mannosides, primarily due to the adverse anomeric and Δ-2 effects. Over the past decades, to attain ß-stereoselectivity in D-rhamnosylation, researchers have devised numerous direct and indirect methodologies, including the hydrogen-bond-mediated aglycone delivery (HAD) method, the synthesis of ß-D-mannoside paired with C6 deoxygenation, and the combined approach of 1,2-trans-glycosylation and C2 epimerization. This review elaborates on the advancements in ß-D-rhamnosylation and its implications for the total synthesis of tiacumicin B and other physiologically relevant glycans.

Chemical approaches for the stereocontrolled synthesis of 1,2-cis-β-D-rhamnosides / 中国天然药物

In carbohydrate chemistry, the stereoselective synthesis of 1,2-cis-glycosides remains a formidable challenge. This complexity is comparable to the synthesis of 1,2-cis-β-D-mannosides, primarily due to the adverse anomeric and Δ-2 effects. Over the past decades, to attain β-stereoselectivity in D-rhamnosylation, researchers have devised numerous direct and indirect methodologies, including the hydrogen-bond-mediated aglycone delivery (HAD) method, the synthesis of β-D-mannoside paired with C6 deoxygenation, and the combined approach of 1,2-trans-glycosylation and C2 epimerization. This review elaborates on the advancements in β-D-rhamnosylation and its implications for the total synthesis of tiacumicin B and other physiologically relevant glycans.

Recent advances in boron-mediated aglycon delivery (BMAD) for the efficient synthesis of 1,2-cis glycosides.

Highly stereoselective synthesis of 1,2-cis glycosides remains a challenging task due to the lack of reliable neighboring group participation (NGP) from the 2-O-acyl functionality in the glycosyl donor. In this context, our group recently developed highly 1,2-cis-stereoselective glycosylation methods, named boron-mediated aglycon delivery (BMAD), using organoboron reagents and 1,2-anhydroglycosyl donors. In this mini-review article, we introduce the BMAD methods and their applications to the synthesis of biologically active natural products and complex glycosides reported since our mini-review article published in this journal in 2017.

Novel 1,2-cis-stereoselective glycosylations utilizing organoboron reagents and their application to natural products and complex oligosaccharide synthesis.

In this mini-review article, 1,2-cis-stereoselective glycosylation methods utilizing organoboron reagents and 1,2-anhydroglycosyl donors that were developed in our laboratory, including regio- and 1,2-cis-stereoselective glycosylations using glycosyl-acceptor-derived boronic ester catalysts and 1,2-cis-stereoselective glycosylations using glycosyl-acceptor-derived borinic ester catalysts, are recounted. Representative applications of these methods to the synthesis of biologically active natural products and a complex oligosaccharide are also described.