HETEROCYCLES

■ Contents

■ Role of Ionic Liquids as Supports of Catalysts

Hisahiro Hagiwara*

*Graduate School of Science and Technology, Niigata University, 8050, 2 no-cho, Ikarashi, Niigata 950-2181, Japan

Abstract

Chemically stable and independent properties of an ionic liquid has been utilized as a liquid support for immobilization of homogeneous or heterogeneous catalysts by simply dissolving or suspending in an ionic liquid. After triturating products with molecular solvent, the catalyst, which was kept in the ionic liquid, is separated, recovered and used repeatedly. Covalent bonding of catalyst residue on an ionic liquid is an alternative method of immobilization. Confine of homogeneous catalyst with the aid of an ionic liquid in pores of amorphous solid (SILPC protocol) is simple and efficient way of immobilization for higher activity, recycle use, easy handling and low cost. Recent representative developments in these areas are reviewed.

■ Asymmetric Synthesis of (-)-Muricatacin’s Analogue (4S,5R)-5-Hydroxy-4-octadecanolide Exhibiting the Cytotoxicity against Esphageal Cancer Cells

Yow-Fu Tsai,* Chien-Cheng Huang, Shiau-Han Lin, Pei-Mei Su, Ying-Ju Chen, and Tzong-Yuan Wu

*Department of Chemistry, Chung Yuan Christian University, 200 Chung Pei Rd., Chung Li 23023, Taiwan, R.O.C.

Abstract

An efficient and facile synthesis, in six steps and 50% overall yield from commercial D-(-)-lyxose as starting material via twice Wittig olefination and one-pot deisopropylidenation and intramolecular lactonization, of the enantiopure (4S,5R)-(+)-5-hydroxy-4-octadecanolide (2), analogue of (-)-muricatacin, and the cytotoxic activity against CE48T cell line (human esophageal carcinoma) are described and the biological activity is the first shown in the literature.

■ Novel Rearrangements of a 8aH-Pyrido[1,2-d]thieno[2’,3’-b][1,4]thiazepine Derivative

Akikazu Kakehi,* Kennosuke Itoh, Hiroyuki Suga, Yuuki Ohkubo, Ayaka Kobayashi, and Takashi Nishi

*Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan

Abstract

The reaction of 5-ethoxycarbonyl-3-[1-(4-methylpyridinio)]-4-phenythiopene-2-thiolate with dimethyl acetylenedicarboxylate in refluxing chloroform or tetrahydrofuran afforded the corresponding 10H-pyrrolo[1,2-d]thieno[2’,3’-b][1,4]thiazocines or the 6,8-dithia-2-azatetracyclo[7.3.2.02,10.03,7]-tetradeca-Δ3,7,4,11,13-tetraene derivative. Also, the thermal conversion from the former product to dimethyl (Z)- and (E)-2-[thieno[2’,3’:2,3][1,4]thiazino[4,5-a]pyrrol-8-ylidene]succinates was confirmed.

■ Scope and Limitations of a Modified Hantzsch Reaction for the Synthesis of Oxazole-Dehydroamino Acid Derivatives from Dehydroamino Acid Amides

Akihiro Nagaya, Yoji Yamagishi, Yasuchika Yonezawa, Shoji Akai,* Chung-gi Shin, and Ken-ichi Sato*

*Department of Material & Life Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan

Abstract

A variety of oxazole derivatives that possess an α,β-unsaturated substituent at the 2-position were conveniently synthesized in good yields via a Hantzsch-type reaction between dehydroamino acid amides and β-bromopyruvate derivatives. Furthermore, oxazoles with substituents at the 2- and 5-positions were also obtained in good yields using the corresponding β-substituted β-bromopyruvate derivatives. A revised reaction mechanism to explain the enhanced reactivity of dehydroamino acid amides for the Hantzsch-oxazole-type reaction is presented.

■ One-Pot Synthesis of Macrocyclic Di- and Tetralactones Using [2+2] Photocycloaddition Reactions of Di-2-pyrones with α,ω-Diolefins

Hui Min Zhang, Kazuya Kawabata, Hideki Miyauchi, and Tetsuro Shimo*

*Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, Korimoto, Kagoshima 890, Japan

Abstract

Sensitized photocycloaddition reactions of 6,6’-dimethyl-4,4’-[1,4-bis(methylenoxy)phenylene]-di-pyrone (1) with poly(ethyleneglycol)divinyl ethers (2a, b) or 2,2’-dimethyltrimethylene dimethacrylate (4), together with the reactions of 6,6’-dimethyl-4,4’-polymethylenedioxy-2-pyrones (6a, b) with 4 were described. The reactions of 1 with 2a, b gave crown ether type macrocyclic compounds (3a and 3a’ (isomer of 3a), 3b and 3b’ (isomer of 3b)) possessing 19- and 22-membered rings across the C3−C4 and C3’−C4’ double bonds in 1, respectively. Similar reactions of 1 with 4 and 6a, b with 4 afforded different types of macrocycles (5 and 5’, 7a, b and 7a’, b’) having 19- to 21-membered rings across the C5−C6 and C5’−C6’ double bonds in 2-pyrone ring. The stereochemical features of 3a’ and 5 were determined by X-ray crystal analysis. The reaction mechanism was inferred by MO methods.

■ Synthesis and Optical Properties of Zincke Salts Having Chiral Anions

Isao Yamaguchi,* Mikihiko Minamitani, and Sachiko Jonai

*Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan

Abstract

Zincke salts having chiral anions were obtained by the anion exchange reaction of Zincke salts having a chloride anion with R-(-)- or S-(+)-binaphthylphospholic acid sodium salts (R-BINAP-PO4Na and S-BINAP-PO4Na). The anion exchange behavior was investigated by photoluminescence measurements. The circular dichroism (CD) spectra of the Zincke salts having R-BINAP-PO4- or S-BINAP-PO4- showed relatively strong negative and positive Cotton effects, respectively.

■ One-Pot Synthesis of 4,8-Dialkylbenzo[1,2-b:4,5-b’]dithiophenes

Ted M. Pappenfus,* Daniel T. Seidenkranz, and Eric W. Reinheimer

*Department of Chemistry, Division of Science and Mathematics, University of Minnesota, 600 East 4th Street, Morris, MN 56267-2128, U.S.A.

Abstract

Two-step, one-pot syntheses are described for the preparation of 4,8-dialkylbenzo[1,2-b:4,5-b′]dithiophenes (BDTs) from alkyllithium or alkyl Grignard reagents. The yields for various alkyl groups used in this procedure are comparable with or exceed those of previously reported methods. The electronic and redox properties of dialkyl-BDTs are compared with the dialkoxy-BDT, 4,8-bis(hexyloxy)benzo[1,2-b:4,5-b']dithiophene. The stabilized HOMO levels of dialkyl-BDTs suggest they are promising building blocks for use in organic photovoltaics such as bulk heterojunction solar cells.

■ Hydrolysable Tannins Isolated from Syzygium aromaticum: Structure of a New C-Glucosidic Ellagitannin and Spectral Features of Tannins with a Tergalloyl Group

Li-Ming Bao, _ Eerdunbayaer, Akiko Nozaki, Eizo Takahashi, Keinosuke Okamoto, Hideyuki Ito, and Tsutomu Hatano*

*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

Eighteen hydrolysable tannins, including a new C-glucosidic tannin named aromatinin A (1), were isolated from an aqueous acetone extract of dried flower buds of Syzygium aromaticum Merr. et Perry. We determined that 1 had a gallic acid C-glucoside structure, based on the spectral data and synthesis from casuarinin (18) and gallic acid (20). This is a rare example of hydrolysable tannins with gallic acid C-glucoside structure. We also report the 1H nuclear magnetic resonance (NMR) spectral features of syzyginin A (2), bicornin (3), and platycaryanin A (4), which were also isolated from S. aromaticum, based on their structures with a tergalloyl group or its depsidone form. The remaining known compounds were identified as alunusnin A (5), rugosin C (6), 1,2,3-tri-O-galloyl-β-D-glucose (7), 1,2,3,6-tetra-O-galloyl-β-D-glucose (8), tellimagrandin II (9), casuarictin (10), heterophylliin D (11), rugosin D (12), rugosin F (13), euprostin A (14), 1,2-di-O-galloyl-3-O-digalloyl-4,6-O-(S)-hexa- hydroxydiphenoy-β-D-glucose (15), alienanin B (16), squarrosanin A (17), and 18. The antifungal effects of hydrolysable tannins, 9, 12, and 18 against Candida strains are also described.

■ Investigation on Amino-Heck Cyclization of 1-(2-Vinylcyclohexyl)ketone Diethyl Phosphinyloximes

Sheng-Wei Tsao and Jia-Liang Zhu*

*Department of Chemistry, National Dong Hwa University, 1, Sec. 2, Hsueh Rd., Shou-Feng, Hualien 974, Taiwan, R.O.C.

Abstract

Upon the treatment with Pd(PPh3)4 and Et3N in DMF at 80 °C, a range of trans-1-(2-vinylcyclohexyl)-substituted ketone diethylphosphinyloximes underwent the cyclization in a 6-endo pathway to afford 1-substituted tetrahydroisoquinolines in varying yields. Among which, the reactions of the substrates bearing the saturated alkyl groups were severely competed by hydrolysis and/or Beckmann rearrangement, while these undesired side reactions could be suppressed by introducing a β-aryl moiety possibly due to the stabilizing π-π stacking interactions between the phosphoryl and/or vinyl group and the aryl rings.

■ A Facile Synthesis of 6-Substituted 7-Arylthieno[2,3-b]pyrazines from 2-Chloropyrazine

Kazuhiro Kobayashi* and Teruhiko Suzuki

*Division of Applied Chemistry, Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

A series of 6,7-disubstituted thieno[2,3-b]pyrazines were prepared by two- or three-pot reaction sequences starting from commercially available 2-chloropyrazine. The reaction of 2-chloro-3-lithiopyrazine with N,N-dimethylbenzamides gave directly aryl(3-chloropyrazin-2-yl)methanones, which were treated successively with sodium sulfide, BrCH2EWG (EWG = CN, CO2t-Bu, COAr), and sodium hydride to give the corresponding 6-substituted 7-arylthieno[2,3-b]pyrazines. Similarly, 6-substituted 7-heterarylthieno[2,3-b]pyrazines were prepared from (3-chloropyrazin-2-yl)heterarylmethanones, derived by the reaction of 2-chloro-3-lithiopyrazine with heteraromatic aldehydes followed by the PCC oxidation.

■ Tumonoic Acids K and L, Novel Metabolites from the Marine-Derived Fungus Penicillium citrinum

Li Chen,* Kai Huang, Ping Zhong, Xiao Hu, Zhe-Xiang Fang, Jiu-lin Wu, and Qi-Qing Zhang*

*Institute of Biomedical and Pharmaceutical Technology & College of Chemistry and Chemical Engineering, Fuzhou University, No. 523, Gongye Road, Fuzhou City, 350002, China

Abstract

Three new compounds, namely tumonoic acids K (1), L (2), and methyl 2-(2-acetyl-3,5-dihydroxy-4,6-dimethylphenyl)acetate (3), together with nine known compounds, were isolated from the marine-derived fungus Penicillium citrinum. The structures of these compounds were elucidated by spectroscopic methods and chemical derivatization. This study is the first to report on tumonoic acid analogues derived from a fungus.

■ PEG-400-Promoted and Ultrasound Assisted Rap-Stoermer Reaction for Efficient Synthesis of Benzofuran-2-yl(carbazolyl)methanone Derivatives

Yang Li, Yan Yan, and Wentao Gao*

*Institute of Superfine Chemicals, School of Chemistry and Chemical Engineering, Bohai University, 19 Keji Road, Jinzhou 121000, China

Abstract

A facile synthesis of hitherto unreported (9-methyl-9H-carbazole-3,6-diyl)bis(benzofuran-2-yl-methanone)s (3a-f) is described, featuring the PEG-400-promoted and ultrasound-asisted Rap-Stoermer reaction of 3,6-dichloroacetyl-9-methyl-9H-carbazole (1) with a variety of salicylaldehydes as well as 2-hydroxy-1-naphthaldehyde (2) in the presence of K2CO3 as the base in acetonitrile. This procedure offers easy access to benzofuran-2-yl(carbazolyl)methanone derivatives in short reaction time and the products are achieved in good yields.

■ Synthesis of 3-Cyanopyrazoles from 3-Trifluoromethyl-pyrazoles via Direct Ammonolysis Reaction

Tao Yan, Yanhong Chen, Jia Wang, Yuyuan Xie, and Chunhao Yang*

*State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, SIBS, Chinese Academy of Science, 555 Zu Chong Zhi Road, Shanghai 201203, China

Abstract

A simple and green method to prepare 3-cyanopyrazoles in aqueous ammonia from easy-obtained 3-trifluoromethylpyrazoles was explored. Most substrates got acceptable yields. The hydrogen position of N1-H on cyanopyrazoles was assigned by X-ray crystal structure analysis.

■ An Efficient One-Pot Synthesis of 1-Amino-3-cyano-4-aryl-10-ethoxycarbonylazuleno[2,1-b]pyrans

Dao-Lin Wang,* Shan-Shan Feng, Qing-Tao Cui, and Jia-Yi Yu

*Liaoning Key Laboratory of Synthesis and Application of Functional Compound, College of Chemistry & Chemical Engineering, Bohai University, Jinzhou 121001, China

Abstract

An efficient and easy method for the one-pot three-component synthesis of 2-amino-3-cyano-4-aryl-10-ethoxycarbonylazuleno[2,1-b]pyran derivatives by the three-componenet condensation of ethyl 2-hydroxyazulene-1-carboxylate, aldehydes, and malononitrile in the presence of diazabicyclo[2.2.2]octane (DABCO) has been described.