Ying-Ming Pan

Ce(OTf)3-Catalyzed [3 + 2] Cycloaddition of Azides with Nitroolefins: Regioselective Synthesis of 1,5-Disubstituted 1,2,3-Triazoles

The first example of rare earth metal-catalyzed [3 + 2] cycloaddition of organic azides with nitroolefins and subsequent elimination reaction is described. In the presence of a catalytic amount of Ce(OTf)3, both benzyl and phenyl azides react with a broad range of aryl nitroolefins containing a range of functionalities selectively producing 1,5-disubstituted 1,2,3-triazoles in good to excellent yields.

Samarium(III)-catalyzed C(sp3)-H bond activation: synthesis of indolizines via C-C and C-N coupling between 2-alkylazaarenes and propargylic alcohols.

A new rare earth metal and samarium-catalyzed C(sp(3))-H bond activation is reported in which 2-alkylazaarenes and propargylic alcohols were converted to indolizines. This process operates under mild conditions and solvent-free conditions. A broad scope of coupling partners has been established, and a likely mechanism has also been suggested.

Synthesis and antitumor activities of novel thiourea α-aminophosphonates from dehydroabietic acid.

A series of novel thiourea α-aminophosphonate derivatives containing DHA structure was designed and synthesized as antitumor agents. Their inhibitory activities against the NCI-H460 (lung), A549 (lung adenocarcinoma), HepG2 (liver) and SKOV3 (ovarian) human cancer cell lines were estimated using MTT assay in vitro. The screening results revealed that many compounds exhibited moderate to high levels of antitumor activities against the tested cancer cell lines and that most demonstrated more potent inhibitory activities compared with the commercial anticancer drug 5-fluorouracil. The mechanism of compound 5f was preliminarily investigated by acridine orange/ethidium bromide staining, Hoechst 33258 staining, JC-1 mitochondrial membrane potential staining, TUNEL assay, DNA ladder assay and flow cytometry, which indicated that the compound can induce cell apoptosis in A549 cells.

Synthesis, Cytotoxic Activity, and DNA Binding Properties of Copper (II) Complexes with Hesperetin, Naringenin, and Apigenin

Complexes of copper (II) with hesperetin, naringenin, and apigenin of general composition [CuL2(H2O)2] ⋅ nH2O (1–3) have been synthesized and characterized by elemental analysis, UV-Vis, FT-IR, ESI-MS, and TG-DTG thermal analysis. The free ligands and the metal complexes have been tested in vitro against human cancer cell lines hepatocellular carcinoma (HepG-2), gastric carcinomas (SGC-7901), and cervical carcinoma (HeLa). Complexes 1 and 3 were found to exhibit growth inhibition of SGC-7901 and HepG2 cell lines with respect to the free ligands; the inhibitory rate of complex 1 is 43.2% and 43.8%, while complex 3 is 46% and 36%, respectively. The interactions of complex 1 and its ligand Hsp with calf thymus DNA were investigated by UV-Vis, fluorescence, and CD spectra. Both complex 1 and Hsp were found to bind DNA in intercalation modes, and the binding affinity of complex 1 was stronger than that of free ligand.

Synthesis and antitumor activities of novel α-aminophosphonates dehydroabietic acid derivatives

A series of novel α-aminophosphonate derivatives containing DHA structure were designed and synthesized as antitumor agents. In vitro antitumor activities of these compounds against the NCI-H460 (human lung cancer cell), A549 (human lung adenocarcinoma cell), HepG2 (human liver cancer cell) and SKOV3 (human ovarian cancer cell) human cancer cell lines were evaluated and compared with commercial anticancer drug 5-fluorouracil (5-FU), employing standard MTT assay. The pharmacological screening results revealed that many compounds exhibited moderate to high levels of antitumor activities against the tested cancer cell lines and that most demonstrated more potent inhibitory activities compared with the commercial anticancer drug 5-FU. The action mechanism of representative compound 7c was preliminarily investigated by acridine orange/ethidium bromide staining, Hoechst 33258 staining, JC-1 mitochondrial membrane potential staining and flow cytometry, which indicated that the compound can induce cell apoptosis in NCI-H460 cells. Cell cycle analysis showed that compound 7c mainly arrested NCI-H460 cells in G1 stage.

Regioselective Synthesis of 1,3,5-Substituted Benzenes via the InCl3/2-Iodophenol-Catalyzed Cyclotrimerization of Alkynes

A novel indium(III)-catalyzed cyclotrimerization of alkynes in the presence of 2-iodophenol gave 1,3,5-substituted benzenes in excellent yields with complete regioselectivity. The reaction condition is tolerant to air, and atom economical, in accordance with the concept of modern green chemistry. This method provides a rapid and efficient access to 1,3,5-substituted benzenes.

Atom-Economical Chemoselective Synthesis of 1,4-Enynes from Terminal Alkenes and Propargylic Alcohols Catalyzed by Cu(OTf)2

A novel and efficient Cu(OTf)2-catalyzed sp(3)-sp(2) C-C bond formation reaction through the direct coupling of propargylic alcohols with terminal alkenes has been realized under mild conditions. The reaction is tolerant to air and is atom-economical, in accordance with the concept of modern green chemistry. The present protocol provides an attractive approach to a diverse range of 1,4-enynes in high to excellent yields.

Synthesis and antitumor activities of novel α-aminophosphonate derivatives containing an alizarin moiety.

A series of novel α-aminophosphonate derivatives containing an alizarin moiety (6-7) was designed and synthesized as antitumor agents. MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay results indicated that most compounds exhibited moderate to high inhibitory activity against KB, NCI-H460, HepG 2, A549, MGC-803, Hct-116, CNE and Hela tumor cell lines. The action mechanism of representative compounds 7h, 7j and 7n were investigated by fluorescence staining assays, flow cytometric analysis and real-time polymerase chain reaction (PCR) assays, which indicated that these compounds induced apoptosis and involved G1 phase arrest by increasing the production of intracellular Ca(2+) and reactive oxygen species (ROS) and affecting associated enzymes and genes. The results demonstrated that these compounds may induce apoptosis through a mitochondrion-dependent pathway.

Palladium-catalyzed synthesis of benzoxazoles by the cleavage reaction of carbon–carbon triple bonds with o-aminophenol

A novel and mild procedure for efficient synthesis of benzoxazoles by the cleavage reaction of carbon–carbon triple bonds with o-aminophenol in the presence of a catalytic amount of palladium chloride has been successfully developed, which provides rapid and efficient access to benzoxazoles.

Regioselective Palladium-Catalyzed Decarboxylative Cross-Coupling Reaction of Alkenyl Acids with Coumarins: Synthesis of 3-Styrylcoumarin Compounds

A novel and efficient protocol for the regioselective synthesis of 3-styrylcoumarins from readily available cinnamic acids and coumarins is presented. The reaction proceeds via a decarboxylative cross-coupling mediated by a catalytic amount of Pd(OAc)2, with Ag2CO3 as an oxidant, and with 1,10-phenanthroline as a ligand. A plausible reaction mechanism for this process is depicted, and the resulting 3-styrylcoumarins show excellent fluorescence quantum yields.