The synthesis of a series of novel 4-substituted 2,3,6,7-tetrahydrobenzo [1,2-b;4,5-b′]difuran–1H-imidazolium salts is presented. The biological properties of the compounds were evaluated in vitro against a panel of human tumor cell lines. Results suggest that the 5,6-dimethyl-benzimidazole or 2-methyl-benzimidazole ring, and substitution of the imidazolyl-3-position with a 2-naphthylmethyl substituent or 2-naphthylacyl substituent, were important to the cytotoxic activity. Notably, 3-(2-Naphthylmethyl)-1-((2,3,6,7-tetrahydrobenzo[1,2-b;4,5-b′]difuran-4-yl)methyl)-1H-5,6-dimethyl-benzimidazol-3-ium bromide (42) was found to be the most potent derivative against five human tumor cell lines with IC50 values of 1.06–4.34 μM and more selective towards SMMC-7721, A549 and SW480 cell lines. 3-(2-Naphthylacyl)-1-((2,3,6,7-tetrahydrobenzo[1,2-b;4,5-b′]difuran-4-yl)methyl)-1H-2-methyl-benzimidazol-3-ium bromide (37) showed higher selectivity to SMMC-7721 and MCF-7 cell lines with IC50 values 2.7-fold and 8.4-fold lower than DDP. Study regarding to the antitumor mechanism of action showed that compound 37 could induce cell cycle G1 phase arrest and apoptosis in SMMC-7721 cells.Download high-res image (168KB)Download full-size image

An efficient palladium-catalyzed α-alkenylation of pyridylmethyl ethers with vinyl bromides is presented. A Pd/NIXANTPHOS-based catalyst system enables a mild and chemoselective coupling between a variety of pyridylmethyl ethers and vinyl bromides in good to excellent yields. Under the mild conditions, β,γ-unsaturated products are obtained without isomerization or Heck byproducts observed.

A series of novel hexahydropyrrolo[2,3-b]indole–1H-imidazolium salts were synthesized and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the 5,6-dimethyl-benzimidazole ring, and substitution of the imidazolyl-3-position with a 2-bromobenzyl or 2-naphthylmethyl group, were important for the cytotoxic activity. Notably, Compound 43, bearing a 2-bromobenzyl substituent at position-3 of 5,6-dimethyl-benzimidazole, was found to possess the most potent derivative against five human tumor cell lines with IC50 values below 2.68 μM and more selective towards SMMC-7721, A549 and SW480 cell lines. Compounds 25 and 39 were more selective to HL-60 and MCF-7 cell lines with IC50 values of 0.47 and 1.46 μM.

A series of novel 2-substituted indoline imidazolium salt derivatives has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of a substituted benzimidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl or 2-naphthylmethyl group were vital for modulating the cytotoxic activity. Compound 25 was found to be the most potent derivative with IC50 values of 0.24–1.18 μM, and exhibited cytotoxic activity selectively against MCF-7, SW480, SMMC-7721 and HL-60 cell lines, while compound 26 showed powerful inhibitory activities selectively against SMMC-7721 and A549 cell lines. Compound 25 can induce G2/M phase cell cycle arrest and apoptosis in SMMC-7721 cells.

A series of novel (±)-3-substituted fluorene–imidazolium/triazolium salt derivatives has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of 2-methyl-benzimidazole or 5,6-dimethyl-benzimidazole rings and substitution of the imidazolyl/triazolyl-3/4-position with a naphthylacyl or 4-methoxyphenacyl group were important for modulating cytotoxic activity. Compounds 37 and 42 were found to be the most potent derivatives with IC50 values of 0.51–2.51 μM and exhibited cytotoxic activities selectively against myeloid leukaemia (HL-60), liver carcinoma (SMMC-7721) and lung carcinoma (A549). Compound 37 can remarkably induce the G2/M phase cell cycle arrest and apoptosis in SMMC-7721 cells. Additionally, compound 30 exhibited selective cytotoxicity to some extent between cancer cells (A549) and normal cells (BEAS-2B).

In the presence of iodine, a functional group compatible method for the deprotection of tert-butanesulfinyl and p-toluenesulfinyl units was developed.

A series of novel 8-substituted 2,3,5,6-tetrahydrobenzo[1,2-b:4,5-b′]difuran imidazolium salt derivatives has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of the 5,6-dimethyl-benzimidazole ring and substitution of the imidazolyl-3-position with a 2-naphthylmethyl or 4-methylbenzyl group were vital for modulating cytotoxic activity. Compound 43 was found to be the most potent derivative and exhibited cytotoxic activities selectively against breast carcinoma (MCF-7), colon carcinoma (SW480), myeloid leukaemia (HL-60) and lung carcinoma (A549) with an IC50 value 65.0-fold, 48.5-fold, 21.2-fold and 19.9-fold more sensitive to DDP, respectively.

A series of novel 1-((indol-3-yl)methyl)–1H-imidazolium salts were prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the 5,6-dimethyl-benzimidazole ring, and substitution of the imidazolyl-3-position with a naphthylacyl or 4-bromophenacyl group, were vital for modulating inhibitory activity of cell growth. In particular, 1-((N-Boc-indol-3-yl)methyl)-3-(2-naphthylacyl)-1H-5,6-dimethyl-benzimidazolium bromide was found to be the most potent derivative and more selective against myeloid liver carcinoma (SMMC-7721), lung carcinoma (A549) and breast carcinoma (MCF-7), with IC50 values 1.9-fold, 1.7-fold and 4.8-fold lower than DDP. This compound can induce significant cell apoptosis in SMMC-7721 cells.

•A series of novel pinocembrin/CD inclusion complexes was prepared.•The inclusion behavior and characterization of pinocembrin with CD were investigated.•The water solubility of pinocembrin was obviously increased in inclusion complexes.•The pinocembrin/CD complexes are much more stable than free pinocembrin.The inclusion complexation behavior, characterization and binding ability of pinocembrin with β-cyclodextrin (β-CD) and its derivative 2-hydroxypropyl-β-cyclodextrin (HPβCD) were investigated in both solution and the solid state by means of XRD, DSC, 1H and 2D NMR and UV–vis spectroscopy. The results showed that the water solubility and thermal stability of pinocembrin were obviously increased in the inclusion complex with cyclodextrins. This satisfactory water solubility and high stability of the pinocembrin/CD complexes will be potentially useful for their application as herbal medicines or healthcare products.

An enantioselective strategy for the synthesis of (+)-brazilin, (−)-brazilein and (+)-brazilide A has been developed. A Lewis acid mediated lactonization established the novel fused bis-lactone core of brazilide A and finalized the first total synthesis of (+)-brazilide A.

A series of novel hybrid compounds between 2-benzylbenzofuran and imidazole has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of benzimidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl or 4-methoxyphenacyl group were vital for modulating cytotoxic activity. In particular, hybrid compounds 46 and 47 were found to be the most potent derivatives against 5 strains human tumor cell lines and more active than cisplatin (DDP), and exhibited cytotoxic activities selectively against breast carcinoma (MCF-7) and myeloid liver carcinoma (SMMC-7721), respectively.Graphical abstractHighlights► Novel hybrid compounds between 2-benzylbenzofuran and imidazole were prepared. ► Their antitumor activity were evaluated. ► The hybrid compounds 47 and 46 were found to be the most potent compounds. ► The structure–activity relationship results of hybrid compounds were summarized.

•Novel dibenzo[b,d]furan–imidazole hybrid compounds were prepared.•Hybrid compound 60 was found to be the most potent derivative.•Hybrid compound 49 was found to be more selective against A549 and SMMC-7721.•The structure–activity relationship results of hybrid compounds were summarized.•Hybrid 60 can induce the G1 phase cell cycle arrest and apoptosis in SMMC-7721 cells.A series of novel hybrid compounds between dibenzo[b,d]furan and imidazole has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of benzimidazole ring, and the substitution of the imidazolyl-3-position with a naphthylacyl or 4-methoxyphenacyl group, were vital for modulating cytotoxic activity. In particular, hybrid compound 60 was found to be the most potent derivatives against all of human tumor cell lines investigated, while compound 49 was found to be more selective against breast carcinoma (MCF-7) and myeloid liver carcinoma (SMMC-7721). Compound 60 can induce the G1 phase cell cycle arrest and apoptosis in SMMC-7721 cells.

A series of novel hybrid compounds between 2-phenylbenzofuran and imidazole have been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that substitution of the imidazolyl-3-position with a naphthylacyl or bromophenacyl group, were vital for modulating cytotoxic activity. In particular, hybrid compound 15 was found to be the most potent compound against 4 strains human tumor cell lines and more active than cisplatin (DDP), and exhibited cytotoxic activity selectively against liver carcinoma (SMMC-7721).A series of novel hybrid compounds between 2-phenylbenzofuran and imidazole have been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that substitution of the imidazolyl-3-position with a naphthylacyl or bromophenacyl group, were vital for modulating cytotoxic activity. In particular, hybrid compound 15 was found to be the most potent compound against 4 strains human tumor cell lines and more active than cisplatin (DDP), and exhibited cytotoxic activity selectively against liver carcinoma (SMMC-7721).

A series of novel 2-substituted indoline imidazolium salt derivatives has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of a substituted benzimidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl or 2-naphthylmethyl group were vital for modulating the cytotoxic activity. Compound 25 was found to be the most potent derivative with IC50 values of 0.24–1.18 μM, and exhibited cytotoxic activity selectively against MCF-7, SW480, SMMC-7721 and HL-60 cell lines, while compound 26 showed powerful inhibitory activities selectively against SMMC-7721 and A549 cell lines. Compound 25 can induce G2/M phase cell cycle arrest and apoptosis in SMMC-7721 cells.

An enantioselective strategy for the synthesis of (+)-brazilin, (−)-brazilein and (+)-brazilide A has been developed. A Lewis acid mediated lactonization established the novel fused bis-lactone core of brazilide A and finalized the first total synthesis of (+)-brazilide A.

In the presence of iodine, a functional group compatible method for the deprotection of tert-butanesulfinyl and p-toluenesulfinyl units was developed.