Changhu Chu

A novel click chitooligosaccharide for hydrophilic interaction liquid chromatography.

A novel chitooligosaccharide stationary phase for hydrophilic interaction liquid chromatography (HILIC) was developed via click chemistry and showed great HILIC characteristics on separation of polar compounds and enrichment of glycopeptides.

Copper-Catalyzed Aerobic Oxidative Coupling of Aromatic Alcohols and Acetonitrile to β-Ketonitriles

A practical, convenient, and cheap copper-catalyzed aerobic oxidative coupling of aromatic alcohols and acetonitrile to β-ketonitriles has been developed. The green C-C bond formation involving the loss of two hydrogen atoms from the corresponding two carbons, respectively, unlocks opportunities for markedly different synthetic strategies.

Silica based click amino stationary phase for ion chromatography and hydrophilic interaction liquid chromatography

A silica based amino stationary phase was prepared by immobilization of propargylamine on azide-silica via click chemistry. This readily prepared click amino stationary phase demonstrated good selectivity in separation of common inorganic anions under ion chromatography (IC) mode, and the triazole ring in combination with free amino group was observed to play a major role for separation of the anions examined. On the other hand, the stationary phase also showed good hydrophilic interaction liquid chromatography (HILIC) properties in the separation of polar compounds including nucleosides, organic acids and bases. The retention mechanism was found to match well the typical HILIC retention.

A novel click lysine zwitterionic stationary phase for hydrophilic interaction liquid chromatography

A novel type of zwitterionic HILIC stationary phase was prepared by covalently bonding the l-azido lysine on silica gel via click chemistry. The key intermediate azido lysine was synthesized by transformation the amino group in l-Boc-lysine to corresponding azido group and subsequent removal of the N-protected group (Boc). Finally, the azido lysine was covalently bonded to silica beads by click chemistry to get click lysine. Its structure was confirmed by FT-IR and elemental analysis. The new stationary phase showed good HILIC characteristics, when it was applied to separate polar and hydrophilic compounds, such as organic acids, cephalosporins and carbapenems. Compared with the commercial stationary phases, such as Atlantics HILIC and ZIC-HILIC, click lysine displayed better or similar chromatographic behaviors.

Click dipeptide : A novel stationary phase applied in two-dimensional liquid chromatography

2D-HPLC is an important technique for the separation of complex samples. Developing new types of stationary phases is of great interest to construct 2D-LC systems with high orthogonality. In this study, a novel stationary phase-Click dipeptide (l-phenylglycine dipeptide) was prepared by immobilization of alpha-azido l-phenylglycine dipeptide on alkyne-silica via click chemistry. In the preparation of this new material, an efficient, inexpensive and shelf-stable diazo transfer reagent (imidazole-1-sulfonyl azide hydrochloride) was utilized to transfer the amino group of l-phenylglycine to corresponding azido group under mild conditions. The Click dipeptide thus prepared was confirmed by FT-IR, solid state CP/MAS (13)C NMR and elemental analysis. The Click dipeptide packing showed high orthogonality with C18, which reached 63.5%. An off-line 2D-RP/RPLC system was developed to analyze a traditional Chinese medicine (TCM)-Rheum Palmatum L. The results showed high orthogonality between Click dipeptide and C18 as well as great separating power in the practical separation of complex samples.

A new amide from Asarum forbesii Maxim.

A highly unsaturated new amide, (2E,4Z,8Z,10Z)-N-isobutyl-2,4,8,10-dodecatetraenamide (1), was isolated in very small quantities from the whole plant of Asarum forbesii Maxim. together with four known compounds, (2E,4E,8Z,10E)-N-isobutyl-2,4,8,10-dodecatetraenamide (2), (−)-sesamin (3), (−)-asarinin (4) andE)-asarone5). The Z/E isomers, 1 and 2, were separated successfully by developed silver-ion medium-pressure liquid chromatography (SIMPLC). Compound 2 and the two diastereoisomers, 3 and 4, were isolated from this plant for the first time. The characterization of these compounds was achieved by various spectroscopic methods.

Click novel glycosyl amino acid hydrophilic interaction chromatography stationary phase and its application in enrichment of glycopeptides

A novel glycosyl amino acid hydrophilic interaction chromatography (HILIC) stationary phase was prepared via click chemistry. The key intermediate N(3)-glycosyl D-phenylglycine was prepared by a three steps procedure, including selective condensation of amino glucose with N-succinimidyl ester of Boc-D-phenylglycine, deprotection and transformation of amino group to azido group. The structure of all the intermediates and functionalized silica beads were confirmed by (1)H NMR, IR, elemental analysis and (13)C CP-MAS. The chromatography test showed that this new type of separation material possessed good HILIC properties and glycopeptide enrichment characteristics. Nucleosides and bases could be separated in a simple eluent composition (only acetonitrile in combined with water), and with the same condition, these model compounds could not be separated on the commercial HILIC column (Atlantis). Click glycosyl amino acid thus prepared also showed longer retention and better separation ability in the separation of polar organic acids.

A novel amide stationary phase for hydrophilic interaction liquid chromatography and ion chromatography.

A novel amide stationary phase (ASP) for hydrophilic interaction liquid chromatography (HILIC) has been prepared via the Click chemistry method. It was based on the strategy that the amino group of Asparagine was easily transferred to the corresponding azido group and then clicked onto terminal alkyne-silica gel in the presence of Cu(I)-based catalyst. For the tested polar compounds including nucleosides and nucleic acid bases, ASP-based column has demonstrated good performance in terms of separation efficiency and column stability, and the retention mechanism was found to match well the typical HILIC retention. In addition, the ASP described here showed much better selectivity in separation of inorganic anions under ion chromatography mode relative to other kinds of commercial ASP.

Click N-benzyl iminodiacetic acid: Novel silica-based tridentate zwitterionic stationary phase for hydrophilic interaction liquid chromatography

Iminodiacetic acid (IDA) is dicarboxylic acid amine, which may produce stronger interaction with polar or charged compounds than bidentate α,β-amino acid. In this article, a novel type of tridentate zwitterionic HILIC stationary phase was prepared by covalently bonding N-benzyl IDA on silica gel via copper(I) catalyzed Huisgen azide-alkyne 1,3-dipolar cycloaddition (CuAAC). The structure of this stationary phase and all related intermediates was confirmed by NMR, FT-IR, MS spectrum and elemental analysis. The new stationary phase showed good HILIC characteristics and high column efficiency (the theoretical plate number is up to 44000 plates m(-1) in the case of guanosine) in the application of separation of polar compounds, including organic acids, organic bases, as well as highly polar and hydrophilic compounds, such as cephalosporins and carbapenems. Most of them displayed good peak shape and selectivity.

One-pot, three-component reaction using modified Julia reagents: a facile synthesis of 4,5-disubstituted 1,2,3-(NH)-triazoles in a wet organic solvent.

A new one-pot, three component reaction involving the use of Julia reagent, aldehyde, and sodium azide was developed for the efficient synthesis of N-unsubstituted 1,2,3-triazoles. This reaction could be carried out under mild reaction conditions without any precaution, and broad scope of substrates, both respect to Julia reagents and aldehydes, could be applied in this reaction system in generation of a small library of title compounds.