Strategies of Synthetic Methodologies for Constructing β-Mannosidic Linkage

Stereocontrolled 1,2-cis glycosylation as the driving force of progress in synthetic carbohydrate chemistry

“…15 The difficulty of direct β-mannosylation was addressed by developing a variety of indirect approaches such as C-2 oxidation-reduction, C-2 inversion, anomeric alkylation, and intramolecular aglycone delivery. 16 This was the standing in the field before Crich and co-workers discovered that 4,6- O -benzylidene protected sulf-oxide 17 or thioglycoside 18 glycosyl donors provide excellent β-manno stereoselectivity. Detailed mechanistic and spectroscopic studies by the Crich group 19 showed that anomeric α- O -triflates generated in situ are reactive intermediates that can be converted into β-mannosides with high stereocontrol at low temperatures.…”

Synthesis and Biophysical Studies on 35‐Deoxy Amphotericin B Methyl Ester

“…Indeed, the introduction of b-mannoside residues remains one of the greatest general challenges to carbohydrate chemistry. [45] We brought a number of the powerful and widely applicable glycosidation methods that have appeared in the literature in the last two decades to bear on this problem with little to show for our efforts. [46] While the lack of success was distressing, it led us to re-examine the union of amphoteronolide 43 and trichloroacetimidate 6 a (Scheme 9, Table 3).…”

Benzyl 2-(4-bromoanilino)-4,4-dimethyl-6-oxocyclohex-1-enecarbodithioate: first triclinic polymorph

“…They are also important reactants in the synthesis of heterocyclic compounds (Tominaga, 1989;Tominaga et al, 1991). Our interest in such class of compounds revolves around new glycosyl donors (El Ashry et al, 2005a, 2005b, 2006, 2008a, 2008b, El Ashry, Kassem et al2009. The title compound is to be used in a model study to understand the scope of the reaction that uses cyclic enaminones.…”