HETEROCYCLES

■ Contents

■ Recent Application of 4-Hydroxycoumarin in Multi-Component Reactions

Ghodsi Mohammadi Ziarani* and Parvin Hajiabbasi

*Department of Chemistry, Alzahra University, Vanak Square, Tehran, P.O. Box number 19938939973, Iran

Abstract

4-Hydroxycoumarin has been utilized in many heterocyclic preparations such as indole-containing compounds, furo- and pyran-annulated, and spiro-compounds. In addition, significant places of its derivatives as pharmaceutical compounds cause it more important. There are a diversity of multi-component reactions of this useful reagent which we highlight the recent reports of them in this review. Also, herein some asymmetric syntheses via 4-hydroxycoumarin is discussed.

■ DIHYDROPYRIMIDINE

Hidetsura Cho*

*Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Aoba-ku, sendai 980-8578, Japan

Abstract

The synthesis history, physical properties (stability and tautomerism), ring construction procedures, a variety of reactions, various skeletons (monocyclic, bicyclic, tricyclic, tetracyclic, bicyclo-, and spiro-), and biological activities of dihydropyrimidines are reviewed.

■ Palmaerins A-D, New Chlorinated and Brominated Dihydroisocoumarins with Antimicrobial and Plant Growth Regulating Activities from Discomycete Lachnum palmae

Yuka Tanabe, Takunori Matsumoto, Tsuyoshi Hosoya, Hiroyasu Sato, and Hideyuki Shigemori*

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

Abstract

A new chlorinated dihydroisocoumarin, palmaerin A (1), and three new brominated dihydroisocoumarins, palmaerins B (2), C (3), and D (4), were isolated from the supernatant of the culture broth containing KCl and KBr of discomycete Lachnum palmae, respectively. The structures of 1-4 were elucidated by spectroscopic data and X-ray diffraction analysis. Compounds 2 and 3 exhibited weak antibacterial activity against Bacillus subtilis and Staphylococcus aureus, while compounds 1-3 showed plant growth regulating activity against Lepidium sativum.

■ Synthesis of Novel 1-Alkyl-1,2-dihydro-2-Imino-4-quinazolinamines by Tandem Reaction of the Three Components

Zhen Guo, Ping Yin, Ling He, and Qing Rong Qi*

*Department of Medicinal Chemistry, Sichuan University, #17 Renmin South Road 3th section, Chengdu 610041, China

Abstract

A novel and efficient synthesis of quinazoline derivatives involving copper-catalyzed Ullmann-type coupling reaction was developed. These reactions were performed under mild conditions without the addition of a ligand. The coupling reaction and the subsequent cyclization reaction in series gave rise to the formation of intermolecular C-N bond and intramolecular C-N bond and synthesized novel N, N'-substituted 2-imino-1, 2-dihydroquinazolin-4-amines in moderate to high yields simultaneously.

■ A Convenient Two-Step Synthesis of 7-Aryl-6,7-dihydrothieno[2,3-b]pyrazines from Aryl(3-chloropyrazin-2-yl)methanones

Kazuhiro Kobayashi,* Teruhiko Suzuki, and Naoki Matsumoto

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

Abstract

An efficient method for the preparation of 7-aryl-6,7-dihydrothieno[2,3-b]pyrazines (3) under mild conditions has been developed. The reaction of aryl(3-chloropyrazin-2-yl)methanones (1), derived from commercially available 2-chloropyrazine, with methylenetriphenylphosphorane in THF at room temperature gave the corresponding 2-(1-arylethenyl)-3-chloropyrazines (2), which were treated with NaSH·nH2O in DMF at room temperature to lead to the desired products (3) in acceptable yields. These products are dehydrogenated with air in refluxing toluene in the presence of a catalytic amount of Pd/C to yield the corresponding 7-arylthieno[2,3-b]pyrazines (4).

■ Synthesis of Dihydro-1-benzazepines

Meng-Yang Chang,* Chieh-Kai Chan, and Shin-Ying Lin

*Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan, R.O.C.

Abstract

A synthetic route toward the benzannulated dihydro-1-benzazepines (8) with two oxygenated groups starting with 2-methoxy-5-nitrophenol (2) in high total yield is described. Two key routes are carried by Claisen rearrangement of allyl phenyl ethers (3) and ring-closing metathesis of dienes (7).

■ Whitmanoside A, a New α-Pyrone Glycoside from the Leech Whitmania pigra

Tao Li, Guo-Cai Wang,* Xiao-Jun Huang, and Wen-Cai Ye*

*College of Pharmacy, Jinan University, 601 West Huangpu Avenue, Guangzhou, 510632, China

Abstract

A new α-pyrone glycoside, whitmanoside A (1), along with eight known compounds, including two furanones (2, 3) and six proline-derived cyclic dipeptides (4-9), were isolated from the dried material of the leech Whitmania pigra. The structures of these compounds were established on the basis of their spectroscopic data and acid hydrolysis. This is the first report on the isolation of these compounds from a leech.

■ Microwave-Assisted Syntehsis of 2-Substituted 1H-Benzo[d]imidazoles and Their Antifungal Activities in vitro

Tao Zhang, Liang-Zhu Huang, Jia Wu, Dong Lu, Bo-Lin Ma, and Zhen-Ting Du*

*College of Science, Northwest A＆F University, Yangling 712100, Shaanxi Province, China

Abstract

An efficient and novel microwave-assisted synthesis of 1H-benzo[d]imidazole derivatives via nitriles and o-phenyldiamines in the presence of polyphosphoric acid (PPA) and phosphoric acid is described. This method provides several advantages such as commercially high availabilities of starting materials, short reaction times, high yields and a simple workup procedure. Systematically antifungal biological tests showed 3f was most promising candidate against six phytopathogenic fungi.

■ Cyclopropanation of Carbon-Carbon Double Bonds in Ring D of Ergot Alkaloids

Mária Incze, Gábor Dörnyei, Péter Kovács, Orsolya Egyed, György Hajós, and Csaba Szántay*

*Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111 Budapest, Szt. Gellért tér 4, Hungary

Abstract

Some alkaloid derivatives containing a double bond in ring D have been reacted with diazomethane/palladium diacetate reagent to result in formation of a fused cyclopropane ring. This procedure proved to be generally applicable for cyclopropanation of Ergot alkaloids.

■ ent-3,4-seco-Labdane Diterpenoids from Callicarpa nudiflora Leaves with Anti-inflammatory Activity

Lei Zhang, Jian Huang, Mingsheng Liu,* Cui Zhang, Guoyu Li, Ke Zhang, Lin Dong, and Jinhui Wang*

*School of Traditional Chinese Materia Medicine, Shenyang Pharmaceutical University, No.103, Wenhua Road, Shenyang, China

Abstract

Two new ent-3,4-seco-labdane diterpenoids, ent-3,4-seco-16-hydroxy-12,15-epoxy-4(18),8(17),12,14-labdatetraen-3-oic acid (1) and ent-3,4-seco-12R,15-epoxy-4(18),8(17),13-labdatrien-3-oic acid (2), were isolated from the leaves of Callicarpa nudiflora. Their structures were elucidated by extensive spectroscopic analysis and the biosynthetic pathways leading to these compounds were proposed. The two compounds both exerted potent inhibitory activity against the production of nitric oxide (NO) in RAW264.7 stimulated by lipopolysaccharide (LPS).