Structural characterization of a series of 10-carbon sugar derivatives by electrospray-ionization MSn mass spectrometry.

Electrospray-ionization MSn mass spectrometry (ESI-MSn) with low-energy, collision-induced dissociation (CID) was used to establish the fragmentation behavior of sodium ion adducts of higher-carbon amino spiro-sugar derivatives. Their fragmentation pathways are proposed on the basis of the MSn studies and deuteration experiments. Some of the rings of these derivatives opened under the conditions of electrospray ionization. Novel fragmentations were observed and their mechanisms are proposed. This study demonstrates the power of modern mass spectrometry for rapid elucidation of the structure of higher-carbon sugar derivatives.

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.

Syntheses of acetylated steroid glycosides and selective cleavage of O-acetyl groups in sugar moiety.

Acetylated 3beta-O-beta-glycosyl steroid derivatives were synthesized by the reaction of a new polyhydroxysteroid 3beta,5alpha,6beta-trihydroxypregn-16-en-20-one (2) with the peracetylated 1-bromo derivatives of d-glucose and d-galactose, respectively. Subsequent protection by excess acetic anhydride in pyridine selectively gave the 6beta-O-acetylated steroid glycosides. Deprotection of the acetylated steroid glycosides separately with moderate catalysis dibutyltin oxide in methanol selectively removed all acetyl groups of sugar moiety, whereas the acetyl group of the steroid part was retained. The structures of the steroid glycosides were confirmed by mass spectrometry, NMR and IR. The complete protocol was shown to be non-destructive at all stages to the sugar moieties and the steroid nucleus. These regioselective reactions open a route to the synthesis of a series of closely related isomers of 2 and other widespread polyhydroxysteroids and steroid glycosides in marine organisms and some terrestrial species.

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

2,2-Bis(C-branched-chain)glucopyranosid-3-uloses, designed for the preparation of biologically active natural product iridoid derivatives, are synthesized selectively by the new reaction of butenolide-containing sugar with active methylene compounds, and the new reaction is clarified as autoxidation followed by Michael addition of carbanion.