Palladium-Catalyzed α-Stereoselective O-Glycosylation of O(3)-Acylated Glycals
نویسندگان
چکیده
Pd(MeCN)2Cl2 enables the α-stereoselective catalytic synthesis of 2,3-unsaturated O-glycosides from O(3)-acylated glycals without the requirement for additives to preactivate either donor or nucleophile. Mechanistic studies suggest that, unlike traditional (η3-allyl)palladium-mediated processes, the reaction proceeds via an alkoxy-palladium intermediate that increases the proton acidity and oxygen nucleophilicity of the alcohol. The method is exemplified with the synthesis of a range of glycosides and glycoconjugates of synthetic utility.
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 کاملA highly efficient dual catalysis approach for C-glycosylation: addition of (o-azaaryl)carboxaldehyde to glycals.
A novel and efficient dual catalysis approach by concurrent activation of glycals and (o-azaaryl)-carboxaldehydes using palladium and N-heterocyclic carbene has been developed. The two electrophiles could react after activation through formation of the Breslow intermediate and a π-allyl Pd complex, widening the scope of reacting glycosylation partners and opening up possibilities for future gly...
متن کاملHighly stereoselective synthesis of aminoglycosides via rhodium-catalyzed and substrate-controlled aziridination of glycals.
The flexible installations of a sulfamate ester on a glycal scaffold at C3, C4, or C6 approaching alpha- or beta-aminoglycosides is communicated. A variety of glycal acceptors (O, S, and N) were applied, enhancing the utility of this method as an operationally simple protocol for the stereoselective synthesis of polyfunctionalized alpha- or beta- aminosaccharides.
متن کاملPalladium-catalyzed haloallylation of aromatic ynol ethers with allyl chlorides: a highly regio- and stereoselective approach to (1E)-α-chloroenol ethers.
Described herein is a Pd-catalyzed haloallylation of aromatic ynol ethers and allyl chlorides, allowing facile access to (1E)-α-chloroenol ethers in a highly regio- and stereoselective manner. The synthetic utility of this method is demonstrated well by the synthesis of the stereodefined multisubstituted enol ethers and α-allylated carbonyl compounds.
متن کاملPalladium-catalyzed decarboxylative acylation of O-methyl ketoximes with α-keto acids.
A mild, practical and efficient palladium-catalyzed decarboxylative ortho-acylation of O-methyl ketoximes with α-keto acids via C-H bond activation is described. In these reactions, a broad range of O-methyl ketoximes and α-keto acids undergoes the decarboxylative cross-coupling reactions with high selectivities and good tolerance.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره 19 شماره
صفحات -
تاریخ انتشار 2017