Weidong Pan

Salen-Ti(OR)4 complex catalysed trimethylsilylcyanation of aldehydes

Abstract Chiral salen-titanium complexes were found to be efficient catalysts for the enantioselective trimethylsilylcyanation of aldehydes. An enantioselectivity up to 87.1% e.e. was obtained by using 10mol% Ti(IV)-salen 2d as catalyst. The reaction mechanism was proposed and proved experimentally.

Synthesis of spiro[4.4]nonane-1,6-diols via the hydrogenation of spiro[4.4]nonane-1,6-dione: the profound effect of hydrogenating agents

Abstract The synthesis of spiro[4.4]nonane-1,6-diols via the catalytic as well as stoichiometric hydrogenation of spiro[4.4]nonane-1,6-dione was studied. Profound effects of the hydrogenation catalysts and reagents on the stereoselectivity of the products were observed. The choice of solvent also was found to have a significant influence on the product selectivity. The opening of a spiro-ring in the starting material was identified as a major side reaction in alcohol solvents. The absolute configuration of the trans, trans-diol was unambiguously determined by X-ray crystallography.

Process development of clinical anti-HBV drug Y101: identification and synthesis of novel impurities

Abstract Nine novel process impurities of N-[N-benzoyl-O-(2-dimethylaminoethyl)-l-tyrosyl]-l-phenylalaninol (Y101) observed during the laboratory optimization and later during its bulk synthesis are described in this article. The impurities were monitored by HPLC, and their structures were tentatively assigned on the basis of fragmentation patterns in LC−MS/MS and NMR spectroscopies. All of the impurities were synthesized, and their assigned constitutions were confirmed by co-injection in HPLC. In addition to the formation, synthesis, and characterization, the strategy for minimizing these impurities to a level accepted by the International Conference on Harmonisation (ICH) was also described.

Synthesis and Biological Evaluation of Matijin-Su Derivatives as Potential Antihepatitis B Virus and Anticancer Agents

A series of Matijin‐Su (MTS, (2S)‐2‐{[(2S)‐2‐benzamido‐3‐phenylpropanoyl]amino}‐3‐phenylpropyl acetate) derivatives were synthesized and evaluated for their anti‐HBV and cytotoxic activities in vitro. Six compounds (4g, 4j, 5c, 5g, 5h and 5i) showed significant inhibition against HBV DNA replication with the IC50 values in range of 2.18 – 8.55 μm, which were much lower than that of positive control lamivudine (IC50 82.42 μm). In particular, compounds 5h (IC50 2.18 μm; SI 151.59) and 5j (IC50 5.65 μm; SI 51.16) displayed relatively low cytotoxicities, resulting in high SI values. Notably, besides the anti‐HBV DNA replication activity, compound 4j also exhibited more potent in vitro cytotoxic activity than 5‐fluorouracil in two hepatocellular carcinoma cell (HCC) lines (QGY‐7701 and SMMC‐7721), indicating that 4j may be a promising lead for the exploration of drugs with dual therapeutic effects on HBV infection and HBV‐induced HCC.

Novel sesquiterpenoids isolated from Chimonanthus praecox and their antibacterial activities

In the present study, four new sesquiterpenoids, chimonols A-D (compounds 1-4), together with four known compounds (5-8) were isolated from the EtOAc extract of Chimonanthus praecox Link. The structures of these new compounds were elucidated on the basis of spectroscopic techniques (UV, IR, MS, and 1D and 2D NMR), and their absolute configurations were established by comparing experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 1-8 were evaluated for antimicrobial activities and the minimum inhibitory concentrations (MICs) were determined by the broth microdilution method in 96-well culture plates. Compounds 1, 2, and 7 exhibited weak antibacterial effects for S. aureus (ATCC 6538), E. coli (ATCC 11775), and P. aeruginosa (ATCC 10145) with MIC values being 158-249 µg·mL-1. Compounds 3-7 showed activities against C. glabrata (ATCC 2001) and S. aureus (ATCC 43300) with MIC values being 128-197 µg·mL-1. Compounds 1-4 showed activity against S. aureus (ATCC 25923) with MIC values being 162-254 µg·mL-1. The present study provided a basis for future evaluation of these compounds as antibacterial agents.

Novel Flavones from the Root of Phytolacca acinosa Roxb.

Two new flavones, 6,7‐methylenedioxy‐4‐hydroxypeltogynan‐7′‐one (1), cochliophilin B (2), as well as two known ones, cochliophilin A (3) and 6‐methoxy‐7‐hydroxy flavone (4), were isolated from the ethanol extract of the root of Phytolacca acinosa Roxb. Compound 1 is a flavanol framework with one δ‐lactone unit, which is rather rare in nature. The structures of the new compounds were determined on the basis of extensive spectroscopic (IR, MS, 1D‐ and 2D‐NMR) analyses, the absolute configuration of 1 was established by comparing experimental and calculated electronic circular dichroism spectra. The structures of known compounds were fixed by comparison with literatures data. Compounds 2 and 4 showed modest inhibitory activities against BEL‐7402 cell line, with IC50 values of 28.22 and 39.16 μmol/L, respectively.