Jiannan Xiang

Synthesis of substituted-phenyl-1,2,4-triazol-3-thione analogues with modified D-glucopyranosyl residues and their antiproliferative activities.

A series of D-glucopyranosyl-1,2,4-triazole-3-thione derivatives 1a-1d were synthesized by the reaction of 1,2,4-triazole-3-thione Schiff bases 5a-5d with 2,3,4,6-tetra-O-acetyl-sigma-D-glucopyranosyl bromide. We demonstrate the conversion of 2 to 5, without the necessity of purification of both oxadiazole and triazole intermediates to afford the compounds 5. Their structures were confirmed by standard studies of (1)H NMR, IR, MS and elemental analysis. Analogues 5 and 1 have shown cytotoxic activity against human MCF-7 and Bel-7402 malignant cell lines.

Synthesis, characterization and in vitro antiproliferative activities of new 13-cis-retinoyl ferrocene derivatives

In order to improve biological behavior of the retinoyl derivatives, monoarylferrocenyl alcohols 9a and 9b were synthesized by an improved Suzuki cross-coupling method and their 13-cis-retinoic acid analogues were prepared in moderate to good yields via the Mitsunobu reaction. Their structures were confirmed by IR, (1)H NMR, (13)CNMR, MS spectra and element analysis and their antiproliferative activities were determined in vitro using human cancer cell lines. The results of bioassay showed that these organometallic analogues exhibited higher antiproliferative activities than parent 13-cis-retinoic acid and other retinoyl derivatives.

Synthesis, characterization and antibacterial activities of some new ferrocene-containing penems.

The synthesis and structure-activity relationships of a series of new penems bearing ferrocenyl group attached to the C-2 position of the penem nucleus were described. The beta-lactanic derivatives obtained had been characterized as sodium salts, through (1)H NMR and IR, as well as through element analysis. Their in vitro antibacterial activities against both Gram-positive including meticillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria were tested. Most of the penems exhibited superior or equivalent efficacy of antibacterial activity as well as high stability to renal dehydropeptidase-I (DHP-I) compared with faropenem. In particular, the compound 14h having a heterocyclic group showed the most potent antibacterial activity.

Synthesis and characterization of biodegradable amphiphilic triblock copolymers methoxy-poly(ethylene glycol)-b-poly(L-lysine)-b-poly(L-lactic acid)

Starting from MPEG-NH2, a series of amphiphilic triblock copolymers MPEG-b-PLL-b-PLA were synthesized through PEG-NH2-initiated ring-open polymerization of Nε-benzyloxycarbonyl-L-lysine, followed by acylation coupling between the amino-terminated MPEG-b-PZLL-NH2 and carboxyl-terminal PLA and the deprotection of amines. The block copolymers were characterized by FT-IR, 1H NMR, GPC, DSC and TEM. The copolymer functional groups, molecular and block structures were verified by FT-IR, 1H NMR and DSC, respectively. The GPC results indicate that the chain lengths of each block can be controlled by varying the feed ratios of the monomer and initiator, providing the polymer samples with a narrow molecular weight distribution (Mw/Mnu2009=u20091.10u2009~u20091.25). The TEM analysis shows that the triblock polymers can self-assemble into polymeric micelles in aqueous solution with spherical morphology. The cell-cytotoxicity assay indicates that the triblock polymers show no obvious cytotoxicity against Bel7402 human hepatoma cells.

Convenient and Efficient Palladium-Catalyzed Coupling Reaction Between Ferroceneboronic Acid and Organic Triflates

A simple and efficient palladium (Pd)–catalyzed Suzuki cross-coupling reaction between ferroceneboronic acid and organic triflates for the preparation of monosubstituted ferrocene derivatives has been developed. A systematic study of various solvents, bases, and catalysts revealed that the combination of Pd(PPh3)4 (0.025 equiv) and K3PO4 (2 equiv) in refluxing dioxane gave reproducible and excellent yields of the coupling products. The reaction could be applied to a wide variety of aryl and vinyl triflates in good to excellent yields, and the electronic and steric effects were observed for ortho-, meta-, and para-substituents of aryl triflates.

New, Simple, and Effective Thiosemicarbazide Ligand for Copper(II)-Catalyzed N-Arylation of Imidazoles

Abstract A new methodology of copper-catalyzed coupling reaction has been developed, involving imidazoles react with aryl halides using CuCl2 · H2O as catalyst and 1-(4-hydroxy-3-me thoxybenzylidene)thiosemicarbazide (L1) as ligand. It is the first time that the complex of new ligand L1 and copper(II) presents better catalytic effects than with copper(I). Because of the stability and economy of copper(II), this methodology will be a promising approach in preparing N-arylimidazoles. GRAPHICAL ABSTRACT

Targeted Anticancer Drug Delivery System: Design and Synthesis

When anticancer drug, paclitaxel, is clinically used, solubility and toxicity are two major problems. To overcome these problems, in the present study, we design a targeted anticancer drug delivery system, which contains drug, drug carrier, and target-differentiated ligand. The key point is that both of paclitaxel and target-differentiated ligand, folate, chemically bond to a biocompatible carrier, heparin, via ester bond and amide bond, respectively. Model reaction indicates that 54% carboxyl groups on the drug carrier are substituted by the model drug and the total yield of model conjugates is ranged from 61 to 66%. The results promise to open a new door for the development of targeted drugs.

A New Non-viral Conjugate as a Promising Carrier System for DNA Delivery

A new nonviral conjugate, chitosan-g-PEI-g-PEG-OH polymer, was synthesized using grafting reaction with chitosan, polyethylenimine and polyethylene glycol for constructing amphiphilic grafting copolymers. The conjugates were characterized by IR and 1HNMR, and can self-assembled to form micelle-like nanoparticles in the aqueous media at the PH value of 5. The size of the nanoparticles was in the range of 30-50 nm. The hydrotropic polymer micelles provide an alternative approach for DNA delivery.