Synthesis of glycosylthiols and reactivity studies

The acid-catalyzed reaction of 1,2-anhydro-3,4,6-tri-O-benzyl-α-d-glucopyranose (7) as glycosyl donor with bis-trimethylsilyl sulfide as acceptor affords the α-thiol. Hence, this sterically hindered S-nucleophile as acceptor should provide with O-glycosyl trichloroacetimidates as glycosyl donors that have nonparticipating groups at C-2, glycosylthiols with the thiol group in axial position. This was confirmed for various donors (4, 16-19) with the exception of the corresponding mannosyl donor (20). However, powerful participating groups at C-2 of the donor (23-28) governed the anomeric selectivity.     

Synthesis of α-glycosyl thiols by stereospecific ring-opening of 1,6-anhydrosugars

Treatment of 1,6-anhydrosugars with commercially available bis(trimethylsilyl) sulfide in the presence of trimethylsilyl triflate led to the formation of α-glycosyl thiols. All the reactions were highly stereoselective and afforded the α-glycosyl thiols in good to excellent yields. By this procedure, a variety of 1,6-anhydrosugars, differing in their sugar units, glycosidic linkages, and protecting group pattern, were converted smoothly into the corresponding α-glycosyl thiols, which could be of great utility in thioglycoside chemistry. It is noteworthy that 1,6-anhydrosugars carrying the 2-O-acyl group and 1,6-anhydrosugar-containing oligosaccharides could also be ring-opened stereospecifically under the same conditions to give rise to the corresponding 1-thiosugars in high yields. Thus, a very concise and efficient access to α-glycosyl thiols of great value was established.     

An effective method for de novo peptide sequencing based on phosphorylation strategy and mass spectrometry

An effective method for peptide sequencing based on phosphorylation strategy and UPLC-MS/MS is proposed in this report. A phosphorylation reaction was carried out by mixing model peptide solution with phosphorylation solution. UPLC-MS/MS was used to analyze and characterize the phosphorylated peptides in the optimized ramp collision energy mode. The results illustrated that this phosphorylation approach significantly strengthened the signal intensity of both a₁ and b series ions of the spectra of the modified peptides. It also can be used to effectively distinguish glutamine (Q) and lysine (K) residues in peptides. The feasibility of this approach was validated by analyzing the trypsin-digested BSA. Data suggested that this proposed method could be a useful tool for the de novo peptide sequencing in proteome research.     

Synthesis of star macromolecules for solid polymer electrolytes

The star macromolecules (SM) were synthesized from phloroglucinol, phosphorus oxychloride, and poly(ethylene glycol methyl ether) with different molecular weight. Structures of the products were characterized by Fourier transform infrared and ¹H-nuclear magnetic resonance. Solid polymer electrolyte films were prepared by mixing the products with poly(ethylene oxide) (PEO) and LiClO₄. The polymer blends of PEO and SM have been characterized by differential scanning calorimetry and thermogravimetry, and the polymer electrolytes have been characterized by alternating current impedance. All the SM products could improve the conductivities of the polymer electrolyte obviously at a temperature range from 20 °C to 80 °C.