Novel autoxidation and Michael addition of a butenolide-containing sugar leading to a C-branched-chain glucopyranosidulose, and X-ray structure of intermediates

One-pot synthesis of heteroaryl diketoalkynyl C-glycoside and dialkynyl di-C-glycoside analogues by three-component successive coupling reaction

The synthesis of heteroaryl diketoalkynyl C-glycoside and dialkynyl di-C-glycoside analogues has been accomplished by successive coupling of heteroaromatics, oxalyl chloride and terminal sugar alkynes in one pot. The three-component coupling reaction catalyzed by CuI gives heteroaryl diketoalkynyl C-glycosides. The same three-component coupling in the presence of n-BuLi produces dialkynyl di-C-glycosides, and the 1:1 of molar ratio of heteroaromatics to terminal sugar alkynes affords the corresponding esters of dialkynyl di-C-glycosides. The desired products have been obtained in good to excellent yields. This sequential one-pot method is mild and efficient, suitable for different heteroaromatics and terminal sugar alkynes. The sugar alkynes include furanosides, pyranosides, and acyclic sugars. Twenty-seven examples have been given. The mechanism for the formation of the desired products has been elucidated.

Concise synthesis of thiophene C-nucleoside analogues bearing sugar residues and aromatic residues through dimerization and sulfur heterocyclization of sugar alkynes and substituted iodoethynylbenzene

The synthesis of thiophene C-nucleoside analogues bearing sugar residues (mono- and disaccharides) and aromatic residues has been achieved by symmetric dimerization of terminal sugar alkynes or unsymmetric dimerization of terminal sugar alkynes and substituted iodoethynylbenzene followed by sulfur heterocyclization in one pot. Homocoupling of terminal sugar alkynes and subsequent sulfur heterocyclization produce thiophene C-nucleoside analogues bearing disaccharides. Unsymmetric dimerization of terminal sugar alkynes and substituted iodoethynylbenzene followed by sulfur heterocyclization give thiophene C-nucleoside analogues bearing monosaccharide and aromatic residues. This approach is concise, general and mild, and is suitable for structurally diverse pyranosides, furanosides, and acyclic sugars. Thirty-two examples have been given and the corresponding products are obtained in moderate to excellent yields.

Novel syntheses of aryl quinoxaline C-nucleoside analogs by mild and efficient three-component sequential reactions

Novel syntheses of aryl quinoxaline C-nucleoside analogs have been accomplished by mild and efficient three-component sequential reactions in high yields with a wide scope of substrates.

Novel regio- and stereoselective phosphonyl radical addition to glycals promoted by Mn(ii)–air: syntheses of 1,2-dideoxy 2-C-diphenylphosphinylglycopyranosides

The novel Mn(ii)–air promoted radical reaction of diphenylphosphine oxide with various glycals in excellent regio- and stereoselectivities generated 1,2-dideoxy-2-C-diphenylphosphinylglycopyranosides.

An efficient synthesis of quinoxaline derivatives from 4-chloro-4-deoxy-α-d-galactose and their cytotoxic activities

A novel and efficient method for the synthesis of quinoxaline derivatives has been developed. Isopropylidenation of 4-chloro-4-deoxy-alpha-D-galactose with 2,2-dimethoxypropane, followed by selective hydrolysis, afforded 2,3-O-isopropylidene-4-chloro-4-deoxy-D-galactose di-methyl acetal (3) as a sole product. Oxidation of compound 3 with (Bu3Sn)2O-Br2 gave corresponding hex-5-ulose derivative in high yields. The hex-5-ulose derivative reacted with o-phenylenediamines under neutral conditions to afford quinoxaline derivatives in reasonable yields. The in vitro cytotoxic activities of these quinoxaline derivatives were investigated.

A facile approach to anhydrogalactosucrose derivatives from chlorinated sucrose

Three new anhydrosucrose derivatives: 1,4:3,6-dianhydro-beta-D-fructofuranosyl 4-chloro-4-deoxy-alpha-D-galactopyranoside (4), 1,4:3,6-dianhydro-beta-D-fructofuranosyl 3,6-anhydro-4-chloro-4-deoxy-alpha-D-galactopyranoside (6) and 1,6-dichloro-1,6-dideoxy-beta-D-fructofuranosyl-3,6-anhydro-4-chloro-4-deoxy-alpha-D-galactopyranoside (8) were prepared from chlorinated sucrose. The structures of these anhydrides were confirmed by their (1)H and (13)C NMR spectra, ESIMS and elemental analysis. The crystal structures of 6 and the acetate of 4 (5) are presented. The relative reactivity of the chloromethyl groups towards S(N)2 reactions in 1,6-dichloro-1,6-dideoxy-beta-d-fructofuranosyl 4,6-dichloro-4,6-dideoxy-alpha-D-galactopyranoside was found to be in order 6>6'>1'.