HETEROCYCLES

■ Contents

■ Synthesis, Stereochemical Stability, and Biological Activity of Stemonamine and Its Related Stemona Alkaloids

Takayuki Iwata and Mitsuru Shindo*

*Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga-koen, Kasuga 816-8580, Japan

Abstract

More than 140 Stemona alkaloids have been isolated from Stemona plants (of the Stemonaceae species). These alkaloids represent a unique pyrrolo[1,2-a]azepine nucleus, and can be classified into eight groups on the basis of their chemical aspects. This study is focused on the synthesis of stemonamine group alkaloids, in addition to their chemical stability and biological activity.

■ Substitution of a Haloquinone by Phenols under Pyridine-Free Conditions: Synthetic, Mechanistic, and Solid-State Considerations Involving 2,3-Dichloro-1,4-naphthoquinone

Nolan J. Blythe, Kristin M. Hutchins, Joshua R. Carpenter, Taylor W. Cox, Andrew M. Johnson, Leonard R. MacGillvray, and Jay Wm. Wackerly*

*Department of Chemistry, Central College, Pella, IA 50129, U.S.A.

Abstract

Benzoquinones fused to heterocycles, like most benzoquinones, have the potential for a wide-array of applications but their inherent reactivity can present a synthetic dilemma. The issue is that a synthesis may target one desired outcome, yet yield a range of side products. In efforts to understand the reaction pathways of haloquinone substitution, while minimizing undesired product formation, four examples of reactions between 2,3-dichloro-1,4-naphthoquinone and phenolic nucleophiles are presented. Two of the products were confirmed and analyzed by X-ray crystallography. The reaction with orcinol was optimized for yield and investigation of this mechanism indicates a novel pathway under pyridine-free conditions.

■ One-Pot Solvothermal Synthesis and X-Ray Structure of a Methylated Terpyridine Derivative as DNA Binder and Anticancer Agent

Yihui Jiang, Keke Chai, Yi Sun, Qiwen Pang, Xiaoli Liu, Min Shi, Jing Wang, Jie Wei, Da Liu, and Jintao Wang*

*Jiangxi Provincial Key Laboratory of Drug Design and Evaluation, School of Pharmacy, Jiangxi Science & Technology Normal University, Nanchang 330013, China

Abstract

A new terpyridine derivative [mterpy]I {(mterpy = 2-[4-(4-methylphenyl)-2,2'-bipyridin-6-yl]-1-methylpyridinum) iodide} was synthesized and characterized by single crystal X-ray crystallography, and π-π stacking interaction was detected in the structure. The new methylated polypyridine ligand [mterpy]I was easily obtained under solvothermal condition. Meanwhile, the product exhibited evident in vitro antiproliferation activity towards cancer cells in methyl-thiazolyl-tetrazolium (MTT) assays.

■ Biological Activity of Sinapic Acid Derivatives Isolated from Raphanus sativus

Takaya Ishida, Aki Hasebe, Xingyun Zhao, and Hideyuki Shigemori*

*Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572 Japan

Abstract

Radish sprout (Raphanus sativus) is a vegetable sprout that contains various sinapic acid derivatives. In this study, three sinapic acid derivatives 1-3 isolated from R. sativus, sinapic acid (4), and compounds 5-7, derived from the methylation of compounds 2-4, respectively, were used to investigate the structure-activity relationship for various bioactivities. Compounds with a number of sinapoyl and phenolic hydroxyl groups were found to have antioxidant and angiotensin converting enzyme (ACE) inhibitory activities. In addition, the sugar domains and the phenolic hydroxyl group in sinapoyl group is related to α-glucosidase inhibitory activity. Therefore, these sinapic acid derivatives are promising candidates to move forward to in vivo studies for the treatment of lifestyle-related diseases such as diabetes and hypertension.

■ Palladium/Benzimidazolium Salt Catalyst Systems and N-Heterocyclic Carbene-Palladium(II)-Pyridine (PEPPSI) Complexes for Anti-Markovnikov Hydroaminations of Styrene in Ionic Liquid

Yetkin Gök, Beyhan Yiğit, Özlem Özeroğlu Çelikal, and Murat Yiğit*

*Department of Chemistry, Faculty of Science and Art, Adıyaman University, 02040 Adıyaman, Turkey

Abstract

Both in situ prepared Pd-NHC and NHC-Pd-PEPPSI complexes were tested as catalysts in the intermolecular hydroamination reactions between styrene with various anilines in ionic liquid. All of the compounds tested here are catalytically active for the intermolecular hydroamination of styrene with aromatic amines. The anti-Markovnikov addition products were obtained selectively by using 1 mol% of the palladium complex.

■ One-Pot Cascade Synthesis of Pyrazole Based Isosteres of Valdecoxib by a [3+2] Cycloaddition Sequence and Evaluation of Their Cox Inhibitory Activity

Silvia Roscales,* Nicole Bechmann, Jens Pietzsch, and Torsten Kniess*

*Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany

Abstract

A series of 5-methyl-3,4-diaryl-substituted 1H-pyrazoles, N-isosteres of valdecoxib, was synthesized by a [3+2] cycloaddition/[1,5] sigmatropic rearrangement sequence starting from tosylhydrazine, aryl methyl ketones and terminal aryl alkynes bearing various substituents (H, Me, OMe, F, SO2Me, SO2NH2). New pyrazoles were prepared regioselectively in a one-pot process with moderate-good yields. All compounds were used in in vitro cyclooxygenase (COX) assays to determine inhibitory potency and selectivity to COX-1 and COX-2. In general, these new pyrazoles are characterized by selective COX-2 inhibition activity in a micromolar range.

■ Synthesis and Optical Studies of 2,4,5-Tri[2-(aryl)ethenyl]-1H-imidazoles

Rabia Babar and Munawar Ali Munawar*

*Institute of Chemistry, University of the Punjab, Lahore 54590, Pakistan

Abstract

A series of Y-shaped 2,4,5-tri(arylethenyl)-1H-imidazoles (2a-2c) has been synthesized. The synthesized compounds have been characterized by IR, NMR, Mass and elemental analyses. The optical properties were investigated by using absorption and emission measurements. The compound 2b, containing nitro group has been found non-fluorescent. The absorption and emission properties have helped us to find the effect of substituent on the optical properties.

■ Three New Arylbenzofuran Lignans from Arctium lappa and Their Anti-Tobacco Mosaic Virus Activity

Wan-Li Zeng, Meng-Jie Liang, Shan-Shan Hu, Qian Gao, Chun-Man Song, Hai-Tao Huang, Yong Xu, Hai-Ying Xiang, Liang Deng, Guang-Yu Yang, Yin-Ke Li, Ya-Dong Guo,* and Qi-Li Mi*

*Key Laboratory of Tobacco Chemistry of Yunnan Province, China Tobacco Yunnan Industrial Co., Ltd, 650231, Kunming, China

Abstract

Three new (1-3), together with two known (4 and 5) arylbenzofuran lignans were isolated from the seed of Arctium lappa. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D-NMR techniques. Compounds 1-3 were evaluated for their anti-tobacco mosaic virus (Anti-TMV) activity. The results showed that compounds 1-3 showed potential anti-TMV activities with inhibition rates of 33.5%, 32.8%, and 34.2%, at the concentration of 20 µM, respectively. These rates are higher than that of positive control.

■ Three New Anti-Tobacco Mosaic Virus Prenyl Chromone Derivatives from Cassia nomame

Yong Xu, Qi-Li Mi, Yin-Ke Li, Wan-Li Zeng, Qian Gao, Chun-Man Song, Hai-Tao Huang, Hai-Ying Xiang, Xue-Mei Li, Guang-Yu Yang, Qiu-Fen Hu,* and Jin Wang*

*Key Laboratory of Chemistry in Ethnic Medicinal Resources, Yunnan Minzu University, Kunming 650031, China

Abstract

Three new (1-3), together with four known (4-7) prenyl chromone derivatives were isolated from the whole plants of Cassia nomame. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D-NMR techniques. Compounds 1-3 were evaluated for their anti-tobacco mosaic virus (Anti-TMV) activity. The results showed that compounds 1-3 showed potential anti-TMV activities with inhibition rates of 34.5%, 36.3%, and 57.2% at the concentration of 20 µM, respectively. These rates are higher than that of positive control.