HETEROCYCLES

■ Contents

■ Plausible Mechanism for the Formation of 2-Methoxy-2H-azepine Derivatives from 3H-Azepines Using Bromine and NBS

Kyosuke Satake,* Christopher Cordonier, Yasuhiro Kubota, Yuexian Jin, and Masaru Kimura

*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

Formation of 2-bromo-4-t-butyl-7-methoxy-2H-azepine and 4-t-butyl-7-methoxy-2-succinimidyl-2H-azepine by the respective reactions of 5-t-butyl-2-methoxy-3H-azepine with bromine and NBS suggests a plausible mechanism for the conversion of 3H-azepine to 2H-azepine as 1,4-addition of an electrophile and a consequent 1,2-dehydrobromination. Different from the case of cycloheptatriene, reaction of 3H-azepine with bromine did not give any delocalized ionic species.

■ Recognition of Nucleotides by Melamine Derivatives Bearing a Guanidinium Ion through Hydrogen Bondings

Shigeki Watanabe, Yuichi Sakuno, Shin-ichi Kondo, and Yumihiko Yano*

*Department of Chemistry, Gunma University, Kiryu, Gunma 376-8515, Japan

Abstract

Melamine derivatives bearing a guanidinium ion were found to extract uridine-5’-monophosphate (UMP) and guanosine-5’-monophosphate (GMP) in water into chloroform layer, whereas not the corresponding nucleosides under the same conditions.

■ 3-Hydroquinolylquinolines and Bisquinolyl-annelated Oxepin as Unexpected Products from the Reaction of p-Benzoquinone and N-Acetyl-1,4-dihydroquinolines

Andreas Hilgeroth* and Burkhardt Voigt

*Institute of Pharmaceutical Chemistry, Department of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany

Abstract

4-Substituted N-acyl-1,4-dihydroquinolines (1a, b) have been yielded by regioselective 4-arylation/alkylation via quinolinium intermediates. Acid-catalysed reaction of 1a, b with p-benzoquinone leads to unexpected 3-hydroquinolylquinolines (5a, b). The structure of compounds (5a, b) has been confirmed by spectroscopical data and additionally by formation of both O-acetyl derivatives (7a, b). Bisquinolyl-annelated oxepin (9a) was found as side product. Formation and stereochemistry of the spectroscopically characterized compound (9a) are discussed.

■ Synthesis of Ferrocenyl-3,4-dihydro-1H-pyrimidin-2-ones

Elena I. Klimova, Tatiana B. Klimova,* Simón O. Hernández, and Marcos G. Martínez

*National Autonomous University of Mexico, Chemical Faculty, Cd. Universitaria, Coyoacán C.P. 04510, Mexico D.F., Mexico

Abstract

Methylurea reacts with linear and cyclic α,β-enones of the ferrocene series to yield ferrocenyl-3-methyl-3,4-dihydro-1H-pyrimidin-2-ones characterized by IR and ¹H and ¹³C NMR spectroscopical data. The structure of 4-ferrocenyl-6-(4-methoxyphenyl)-3-methyl-3,4-dihydro-1H-pyrimidin-2-one is confirmed by X-Ray diffraction analysis.

■ Synthesis of 10-Hydroxy-3-methyl-1H-pyrano[4,3-b]quinoline Derivatives

Mieko Morone, Atsuko Sato, and Yutaka Azuma*

*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

Heating of 4-arylamino-3-ethoxycarbonyl-6-methyl-2H-pyran-2-one derivatives (3), which were obtained from the reaction between 4-chloro-3- ethoxycarbonyl-6-methyl-2H-pyran-2-one (2) and anilines, in PPA gave corresponding 10-hydroxy-3-methylpyrano[4,3-b]quinoline derivatives (4) and 1-(4-hydroxyquinolin-2-yl)propan-2-one (5).

■ Photoreaction of 9-Methylbenz[c]acridine with Diphenylacetic Acid in the Chiral Cocrystal

Hideko Koshima,* Ayaka Nakata, Masaki Nagano, and Haitao Yu

*Department of Applied Chemistry, Faculty of Engineering, Ehime University, Matsuyama, 790-8577 Ehime, Japan

Abstract

Despite 9-methylbenz[c]acridine and diphenylacetic acid are achiral molecules, chiral cocrystal was obtained by crystallization from the solution. Irradiation of the enantiomorphous cocrystals caused photodecarboxylation to afford almost racemic photodecarboxylative condensation product as one of the minor products. Reason for the unsuccessful absolute asymmetric photoreaction was discussed based on the molecular arrangement in the lattice.

■ Investigation of the Intermolecular Pauson-Khand Reaction of Various 1-Alkynes with Cyclic Exo-methylene Compounds

Miyuki Ishizaki,* Mieko Zyo, Yasuhiro Kasama, Yuka Niimi, Osamu Hoshino,* Kiyoshi Nishitani, and Hiroshi Hara

*Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan

Abstract

Intermolecular Pauson-Khand reaction of various 1-alkynes with 4-exo-methylenepiperidine and -cyclohexane derivatives to give corresponding spirocyclopentenones was investigated. The reaction of m- and p-substituted arylalkynes furnished corresponding spirocyclic compounds in good yields, while that of o-substituted arylalkynes and 1-hexyne proceeded in nil to moderate yield.

■ Ring Transformation Reactions Starting from 6-Imino-6H-1,3-thiazines

Detlef Briel

*Institut für Pharmazie, -Pharmazeutische Chemie-, der Universität Leipzig, Brüderstr. 34, D-04103 Leipzig, Germany

Abstract

Ring transformation reactions of 6-imino-6H-1,3-thiazines (4), 6-imino-6H-1,3-thiazine hydroperchlorates (3), respectively, are initiated under basic conditions by a ring opening of the thiazine nucleous. Two possibilities exist, either intramolecular elimination occurs to give acrylonitriles (5), or addition of a nucleophile (YH) results in the formation of substituted acrylthioamides (6). The way by which stable products were formed depends on both the functionality of the thiazine, and the reaction conditions. The way 4 → 5 produce 1,3-benzoxazines (8), or 1,2,4-dithiazoles (14), respectively. The way 4 → 6 gives pyrimidinethiones (7), or 1,2-dithioles (17), respectively. Upon treatment of thiazine perchlorates (3) with alkylhalides under basic conditions, acrylonitriles (18) are formed by the way 4 → 5. Compounds (18) can be transformed to 1,2,4-triazoles (19).

■ One-Pot Synthesis of 1,2,4-Oxadiazoles Mediated by Microwave Irradiation under Solvent-free Condition

Babak Kaboudin* and Kian Navaee

*Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45195-159, Iran

Abstract

Microwave-assisted synthesis of 1,2,4-oxadiazoles of amidoximes under solvent free conditions was found to be an efficient method for one-pot synthesis of 1,2,4-oxadiazole derivatives from amidoximes and acyl chlorides. This method is an easy, rapid, and high-yielding reaction for the synthesis of 1,2,4-oxadiazoles.

■ Synthesis of Rigid Bicycloheterocyclic Scaffolds from Vince’s Lactam (Enzymatic Resolution of Vince’s Lactam)

Mukund K. Gurjar,* Smritilekha Bera, Rohini R. Joshi, and Ramesh A. Joshi

*National Chemical Laboratory, Pune 411 008, India

Abstract

Vince’s lactam, on oxidative cleavage and reduction, produced the 3,5-dihydroxymethylpyrrolidin-2-one derivative. This precursor has been utilized in intramolecular cyclization reactions to design some unique diaza-, oxaaza-, and thiaaza-bicyclic molecules as potential scaffolds in combinatorial chemistry.

■ The Electronic Effects on the Formation of N-ArylMaleimides and Isomaleimides

Ljiljana Fruk and Duncan Graham*

*Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, U.K.

Abstract

The synthesis of a range of aromatic maleimides and isomaleimides is reported. The effect of different substituents on the aromatic system and the products formed is also discussed.

■ Synthesis of 3-Substituted Pyrrole Derivatives with Oligo(ethylene Glycol) Chains

Jie-Wen Zhu and Hai-Bao Chen*

*State Key Laboratory of Bio-organic and Natural Product Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China

Abstract

An etherification method via alkoxymethyleniminium salt is described. Three pyrrole derivatives with oligo(ethylene glycol) chains at the 3-position were synthesized for the first time using the above method as the key step.

■ New 1-Substituted 4-Cinnamoyl-5-hydroxypyrazoles and Precursors Thereof: Synthesis, Ring Closure Reactions and NMR-Spectroscopic Investigations

Wolfgang Holzer* and Ingrid Krca

*Department of Pharmaceutical Chemistry, University of Vienna, Pharmaziezentrum, Althanstrasse14, A-1090 Vienna, Austria

Abstract

Reaction of 1-substituted 5-hydroxy-1H-pyrazoles (pyrazolones) with trans-cinnamoyl chloride / calcium hydroxide in dioxane affords the corresponding 4-cinnamoyl-5-hydroxy-1H-pyrazoles. Cyclization of the latter into 5,6-dihydropyrano[2,3-c]pyrazol-4-ones proceeds in very low yields upon treatment with concentrated sulfuric acid. 1,6-Diphenyl-1H-pyrano[2,3-c]pyrazol-4-one was synthesized by reaction of of 4-acetyl-5-hydroxy-1-phenyl-1H-pyrazole with benzoyl chloride and lithium bis(trimethylsilyl)amide and subsequent cyclization of the thus obtained 1,3-diketone. NMR-spectroscopic investigations with the obtained 4-substituted 5-hydroxypyrazoles and their precursors regarding their tautomeric behavior in various solvents are presented.

■ Epoxidation of Quinones with Urea Hydrogen Peroxide

Jaime A. Valderrama,* M. Florencia González, and Cristián Torres

*Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Santiago-22, Chile

Abstract

Quinones reacted with urea-hydrogen peroxide complex in the presence of a base at room temperature, to give the corresponding quinone epoxides in 22-92% yields. The advantages of this new quinone epoxidation procedure are the requirement of organic solvent media, a easily handled solid reagent and a simple workup procedure.

■ Short Syntheses of Melatonin

Helmut M. Hügel* and Faizul Nurlawis

*Department of Applied Chemistry, RMIT University, GPO Box 2476V Melbourne 3001 Victoria, Australia

Abstract

The chemistry concerning the most recent syntheses of melatonin (N-acetyl-5-methoxytryptamine) is described.