AbstractAryl- and amino-substituted pyrimidine C-nucleoside analogs have been synthesized in good to excellent yields by one-pot coupling of terminal sugar alkynes, substituted benzoyl chlorides, and amidine salts. The reaction conditions are tolerant of various structurally complex sugars having sterically bulky groups, unprotected hydroxyl groups, and sensitive substituents. The sugar alkynes include structurally diverse pyranosides, acyclic glycosides, and furanosides. The substituted benzoyl chlorides bear electron-withdrawing and -donating substituents with different steric hindrance. The amidine salts include acetamidine hydrochloride, benzamidine hydrochloride, and guanidine hydrochloride.

•Fifty-six novel 1,2-diketones have been synthesized for the first time.•The method is tolerant of sensitive groups and sterically bulky substituent.•The het (aryl) iodides include sterically bulky heterocycles and iodobenzenes.A new approach for one-pot synthesis of novel sugar/heterocyclic(aryl) 1,2-diketones has been achieved by the reaction of various sugar terminal alkynes with heterocyclic(aryl) iodides at room temperature. This one-pot protocol includes Sonogashira coupling and mild n-Bu4NMnO4 oxidation reaction. This method is mild, general and efficient. Fifty-six examples have been given and the sugar/heterocyclic(aryl) 1,2-diketones were obtained in 71–94% yields. The sugar terminal alkynes include 9 structurally different sugars in pyranose, furanose, and acyclic form which have various protecting groups, sensitive groups, and sterically bulky substituents. The heterocyclic(aryl) iodides include sterically bulky heterocyclic compounds and iodobenzenes with electron-donating, electron-neutral, and electron-withdrawing substituents.

Novel syntheses of C-nucleoside analogs with aryl quinoxalines as nucleobase surrogates have been accomplished by mild and efficient three-component sequential reactions in high yields with a wide scope of substrates. The mechanism was clarified by isolation of novel sugar 1,2-diketone derived from oxidation of the corresponding alkyne.

1,2-Dideoxy-2-C-diphenylphosphinylglycopyranosides were first synthesized by the novel Mn(II)–air promoted reaction of diphenylphosphine oxide with various glycals in high yields with excellent regio- and stereoselectivities, which was clarified as a radical addition reaction controlled by the oxygen of vinyl ether.

The synthesis of substituted mono- and diindole C-nucleoside analogues has been achieved in good to excellent yields by sequential Sonogashira coupling/NaAuCl4-catalyzed heteroannulation reactions of substituted 2-iodoanilines with various sugar terminal alkynes in one pot. The method is general, mild, and efficient and suitable for a wide range of sugar substrates, and 42 examples are given. The amino group of the substituted 2-iodoanilines is unprotected. The sugar terminal alkynes include furanosides, pyranosides, and acyclic glycosides with free hydroxyl groups, sensitive functional subtituents, and various protecting groups having different steric hindrance.

The building block of N-alkyl derivative of allosamidin (chitinase inhibitor), 4,6-O-benzylidene-N-octyl-d-allosamine hydrochloride was stereoselectively synthesized in two steps under mild conditions. Nucleophilic addition of octylamine to 2-oxoglucopyranoside gave a ‘carbonyl group transfer’ product in 62% yield. Subsequent stereoselective reduction of newly formed CO with NaBH4 produced title compound in 75% yield. X-ray diffraction analysis indicates the title compound adopts syn 1, 2, 3 stereochemistry and chair–chair conformation. The crystal structure is stabilized by hydrogen bonds.

Novel methyl 4,6-O-benzylidenespiro[2-deoxy-α-d-arabino-hexopyranoside-2,2′-imidazolidine] and its homologue methyl 4,6-O-benzylidene-3′,4′,5′,6′-tetrahydro-1′H-spiro[2-deoxy-α-d-arabino-hexopyranoside-2,2′-pyrimidine] have been synthesized in good yields by reaction of methyl 4,6-O-benzylidene-α-d-arabino-hexopyranosid-2-ulose with 1,2-diaminoethane and 1,3-diaminopropane. The results are completely different from the reaction with arylamines or alkylamines. One-pot synthesis of novel (E)-methyl 4-[hydroxy (methoxy)methylene]-5-oxo-1-alkyl-(4,6-O-benzylidene-2-deoxy-α-d-glucopyranosido)[3,2-b]pyrrolidines has been achieved by the reaction of alkylamines with the butenolide-containing sugar, derived from the aldol condensation of methyl 4,6-O-benzylidene-α-d-arabino-hexopyranosid-2-ulose with diethyl malonate. These sugar-γ-butyrolactam derivatives are potential GABA receptor ligands.

Novel syntheses of C-nucleoside analogs with aryl quinoxalines as nucleobase surrogates have been accomplished by mild and efficient three-component sequential reactions in high yields with a wide scope of substrates. The mechanism was clarified by isolation of novel sugar 1,2-diketone derived from oxidation of the corresponding alkyne.

1,2-Dideoxy-2-C-diphenylphosphinylglycopyranosides were first synthesized by the novel Mn(II)–air promoted reaction of diphenylphosphine oxide with various glycals in high yields with excellent regio- and stereoselectivities, which was clarified as a radical addition reaction controlled by the oxygen of vinyl ether.