A 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 glycosylation.

Dual-function Pd/NHC catalysis: tandem allylation-isomerization-conjugate addition that allows access to pyrroles, thiophenes and furans.

An efficient coupling reaction of allyl acetate with (O-azaaryl)carboxaldehyde by Pd-NHC dual catalysis has been developed. This reaction proceeds via direct coordination between the ortho nitrogen atom in the heterocycle and Pd(0). This dual catalysis is achieved under mild conditions to give 1,4-diones as products with up to 90% yield.

Oxidative Heck reaction of glycals and aryl hydrazines: a palladium-catalyzed C-glycosylation.

An efficient Heck-type C-glycosylation of glycals via the C-N bond cleavage of aryl hydrazines has been developed. The flexibility of the reaction was tested by the substrate scope, consisting of glycals from different carbohydrate origins as well as aryl hydrazines with various substituents. Pure α-C-glycosides were obtained when (3R)-glycals were employed, whereas α,β mixtures were observed with (3S)-glycals.

Exploring the native chemical ligation concept for highly stereospecific glycosylation reactions.

Various O-alkyl glycosides were obtained in a highly stereospecific manner with retention of configuration at the anomeric center. Our method has customized native chemical ligation concept for glycoconjugates synthesis, utilizing a meticulously controlled activating system. To explain the origin of stereoselective preference, an S(N)i mechanism was proposed and corroborated by computational calculations.

Access to quinolines through gold-catalyzed intermolecular cycloaddition of 2-aminoaryl carbonyls and internal alkynes.

A facile and general method leading to polyfunctionalized quinolines was developed. In the presence of a highly efficient combination encompassing (PPh)(3)AuCl and AgOTf, the reactions between 2-aminocarbonyls and an array of internal alkynes proceeded smoothly to afford quinoline derivatives in good to excellent yields (up to 93%).

Direct synthesis of pyrroles via a silver-promoted three-component reaction involving unusual imidazole ring opening.

A novel silver-promoted three-component reaction toward the synthesis of multifunctionalized pyrroles has been developed. This reaction involves an unusual imidazole ring decomposition, presumably via 1,5-isomerization and subsequent hydrolysis.

Palladium catalyzed stereoselective C-glycosylation of glycals with enol triflates.

An efficient palladium catalyzed C-glycosylation of glycals with enol triflates has been established. The coupling reactions took place on the anomeric carbon, and the coupling products gave exclusively α isomers. The flexibility of the reaction was exemplified by the broad spectra of substrate scope, constituted of glycals protected with good leaving groups as well as an assortment of enol triflates.

Palladium-catalyzed direct cross-coupling reaction of glycals with activated alkenes.

An efficient method for a Pd(OAc)(2)-catalyzed cross-coupling reaction of glycals with activated alkenes under mild conditions has been developed. This transformation provides an expedient synthetic method to C(2)-functionalized glycals, which are common structural building blocks in natural products and other biologically active compounds. The reaction scope includes different kinds of carbohydrates, protecting groups and substituents on alkene.

Quick access to druglike heterocycles: facile silver-catalyzed one-pot multicomponent synthesis of aminoindolizines.

A direct and efficient approach to 1-aminoindolizines through three-component one-pot reaction of heteroaryl aldehydes, secondary amines, and terminal alkynes catalyzed by AgBF(4) has been developed. Desired products were obtained in moderate to excellent yields. Similar aminoindolizines products were afforded from trimethylsilyl protected alkyne substrates as well.