Direct and Stereoselective Synthesis of α-Linked 2-Deoxyglycosides
نویسندگان
چکیده
منابع مشابه
Palladium‐Catalyzed Direct Stereoselective Synthesis of Deoxyglycosides from Glycals
Palladium(II) in combination with a monodentate phosphine ligand enables the unprecedented direct and α-stereoselective catalytic synthesis of deoxyglycosides from glycals. Initial mechanistic studies suggest that in the presence of N-phenyl-2-(di-tert-butylphosphino)pyrrole as the ligand, the reaction proceeds via an alkoxy palladium intermediate that increases the proton acidity and oxygen nu...
متن کاملTMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals
The thio-additions of glycals were efficiently promoted by a stoichiometric amount of trimethylsilyl bromide (TMSBr) to produce S-2-deoxyglycosides under solvent-free conditions in good to excellent yields. In addition, with triphenylphosphine oxide as an additive, the TMSBr-mediated direct glycosylations of glycals with a large range of alcohols were highly α-selective.
متن کاملA 3,4-trans-Fused Cyclic Protecting Group Facilitates α-Selective Catalytic Synthesis of 2-Deoxyglycosides**
A practical approach has been developed to convert glucals and rhamnals into disaccharides or glycoconjugates with high α-selectivity and yields (77-97%) using a trans-fused cyclic 3,4-O-disiloxane protecting group and TsOH⋅H2O (1 mol%) as a catalyst. Control of the anomeric selectivity arises from conformational locking of the intermediate oxacarbenium cation. Glucals outperform rhamnals becau...
متن کاملCooperative Brønsted Acid-Type Organocatalysis for the Stereoselective Synthesis of Deoxyglycosides
A practical approach for the α-stereoselective synthesis of deoxyglycosides using cooperative Brønsted acid-type organocatalysis has been developed. The method is tolerant of a wide range of glycoside donors and acceptors, and its versatility is exemplified in the one-pot synthesis of a trisaccharide. Mechanistic studies suggest that thiourea-induced acid amplification of the chiral acid via H-...
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ژورنال
عنوان ژورنال: Organic Letters
سال: 2008
ISSN: 1523-7060,1523-7052
DOI: 10.1021/ol801833n