Stereoselective synthesis of 2,2-bis(C-branched-chain)glucopyranosid-3-ulose via an autoxidation-Michael addition reaction

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.

A concise asymmetric total synthesis for structure elucidation of 5,6-secoiridoid from Incarvillea argute

A phytochemical investigation of the roots of Incarvillea arguta led to the isolation of secoarguterin (1), which is the first example of 5,6-secoiridoid.

Methyl-α-D-2-selenonyl Pent-2-enofuranoside: A Reactive Selenosugar for the Diversity Oriented Synthesis of Enantiomerically Pure Heterocycles, Carbocycles, and Isonucleosides

The construction of vinyl selenone on a furanoside led to a highly reactive synthetic intermediate methyl-α-D-2-selenonyl pent-2-enofuranoside composed of a masked aldehyde, an electron-deficient double bond along with an excellent leaving group. This new Michael acceptor on reactions with different nucleophiles afforded bicyclic azasugars, cyclopropanated carbohydrate, dihydrofuran- and dihydroisoxazole- substituted furanosides, and isonucleosides in moderate to good yields. Hydrolysis of the hemiacetal linkage of some of these modified carbohydrates afforded enantiopure aziridines, nitrocyclopropane, and dihydrofuran.

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.

Recent advances in the stereoselective synthesis of carbohydrate 2-C-analogs

C-branched carbohydrates are of current interest for glycochemistry, are widely found in nature and serve as important subunits in many antibiotics, bacterial polysaccharides and macrolides. Among C-functionalized saccharides, 2-C-branched carbohydrates represent challenging structures for synthetic chemists, since in contrast to C-glycosides they are not easily accessible from glycosyl bromides or other simple precursors. In this perspective we want to summarize recent approaches to 2-C-branched carbohydrates over the past fifteen years. The two main strategies are based on ring-opening of 1,2-cyclopropanated carbohydrates by various reagents, as well as radical additions to glycals and further transformations, developed in our group. Both methods are characterized by high stereoselectivities and good yields and give access to a broad variety of functionalized carbohydrate 2-C-analogs.

Differential use of anhydropyranosides for enantiopure routes to bis-gamma-butyrolactones: a new approach to the frameworks of antibiotic and anticancer agents isoavenaciolide and ethisolide

Regio- and chemoselective syntheses of enantiopure bis-furanoids are described. These compounds are chirons for several families of bioactive natural products, including isoavenaciolide and ethisolide. Reaction of a 3,4-epoxy pyran with beta-ketoester dianions delivers substituted pyranosides in high yield. Cyclization then yields fused furan-pyran intermediates. Oxidation, deprotection, and rearrangement lead to bis-furanoids that bear the essential framework and stereochemistry of ethisolide and isoavenaciolide.

Asymmetric synthesis of novel tetrahydroquinoline derivatives with a sugar building block and their bioactivities

Some novel spiro-tetrahydroquinolines were stereoselectively synthesized by using keto-sugar derived from sucrose as a building block in one pot under mild conditions. The in vitro immunobiological activity and cytotoxicity of these novel tetrahydroquinolines were investigated. The results implied that these spiro-compounds have obvious bioactivity and may be structurally modified to improve bioactivity further.

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'.