HETEROCYCLES
An International Journal for Reviews and Communications in Heterocyclic ChemistryWeb Edition ISSN: 1881-0942
Published online by The Japan Institute of Heterocyclic Chemistry
Regular Issue
Vol. 53, No. 8, 2000
Published online:
■ Bis[oxo/thioxothiazolinyl] Aromatic Compounds — Stereochemical Aspects
Anca Hîrtopeanu, Marina Mihai, Gheorghe Mihai, and Christian Roussel*
*E.N.S.S.P.I.C.A.M., Avenu Escadrille Normandie-Niemen, 13397 Mareseille Cedex 20, France
Abstract
The geometry, equilibrium compositions and barriers to rotation for the bis[oxo/thioxothiazolinyl] aromatic compounds (1-4), a series of atropisomers with two stereogenic C(aryl) - N(heterocycle) axes are reported. Comparison of the experimentally determined barriers to rotation provides information about the electronic and steric substituent contributions to the barriers, as in the series there is variation of dipoles and of substituents on the heterocyclic or the aromatic part.
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■ A Diamine-Exchange Reaction of Dihydropyrazines
Tadatoshi Yamaguchi,* Shigeru Ito, Yukiko Iwase, Kenji Watanabe, and Kazunobu Harano
*Department of Hygiene, Miyazaki Medical College, Kiyotake-cho, Miyazaki 889-1601, Japan
Abstract
Dihydropyrazines reacted with 1,2-diamines to form tetraazadecalins as intermediates, and then the reaction proceeded forward to dissociate into alternate dihydropyrazine and diamine, or backward to dissociate into the starting materials in certain equilibrium. The product distribution is controlled by diamine-exchange equilibrium reaction. The various equilibrium reactions were analyzed by NMR spectroscopy .
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■ Total Synthesis of Antioxidant Alkaloid Carazostatin via Electrocyclic Ring Closure of 3-Butadienyl-2-methoxyindole
Yoshinori Nonaka,* Tomomi Kawasaki, and Masanori Sakamoto*
*Kissei Pharmaceutical Co., LTD., 4365-1 Kashiwabara, Hotaka, Minamiazumi, Nagano 399-8304, Japan
Abstract
Total synthesis of the naturally occurring antioxidant carazostatin was accomplished by an efficient method, Wittig reaction of 2-methoxyindol-3-one followed by electrocyclic reaction of 3-(1,3-butadienyl)indole.
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■ Synthesis of Bornene Ring-fused Dihydrothiopyrans, a New Class of Chiral Cyclic Sulfides, via Intramolecular Hetero Diels-Alder Reaction of Homochiral Thiabutadienes, 3-(Arylmethylene)thiocamphors
Takao Saito,* Hisakazu Furuie, Yuko Ishigo-oka, Itaru Watanabe, and Kimiko Kobayashi
*Department of Chemistry, Faculty of Science, Science University of Tokyo, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
Abstract
A highly diastereoisoface-selective intramolecular hetero Diels-Alder reaction of homochiral camphor-derived thiabutadienes to afford novel, optically active bornene ring-fused dihydrothiopyrans is described for the first time.
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■ Synthesis of Oxepanes via Indium Chloride Mediated and Tin Chloride Catalyzed Prins-Type Cyclization
Jianke Li and Chao-Jun Li*
*Department of Chemistry, Tulane University, New Orleans, Louisiana, 70118, U.S.A.
Abstract
Various potential cancer-preventive agents, oxepanes, were synthesized by indium(III) chloride mediated, tin chloride(IV) catalyzed cyclization of allylphenol with aldehydes and ketones.
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■ Synthesis of Pentacyclic Ring Systems, Indolo[2,3-a][1,2]oxazino[5,6-i]quinolizine and Indolo[2,3-a]pyrano[3,2-i]quinolizine, and Their Application for the Synthesis of Eburnamine-Vincamine Alkaloids
András Nemes,* János Kreidl, László Czibula, Katalin Nógrádi, Mária Farkas, Csaba Szántay Jr., Gábor Tárkányi, Gábor Balogh, Ida Juhász, Alajos Kálmán, and László Párkányi
*Chemical Works of Gedeon Richter Ltd., Technological Research Laboratory No.I, Budapest 10, P. O. Box 27, H-1475 Budapest, Hungary
Abstract
15a-Ethyl-14-carboxylic esters of the title pentacycles (6) and (8) were prepared via Wenkert’s enamine (4). Both compounds can be readily transformed into indoloquinolizinylpyruvate oxime esters (5), key intermediates for the synthesis of vincamine alkaloids. The ring/chain equilibrium observed for compounds (6) and (8) was studied by UV and NMR spectroscopic methods.
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■ The Synthesis of an Aminohexyl-containing Analog of the Chromanol Leukotriene B4 Receptor Antagonist CP-195543: A Scaffold for the Preparation of Derivatized Analogs
Brian P. Jones, Klaas Schildknegt, Kathyrn F. Wright, Henry J. Showell, James P. Dittami, Keith E. McCarthy, and Lawrence A. Reiter*
*Pfizer Inc., Central Research Division, Eastern Point Road, Groton, Connecticut 06340, U.S.A.
Abstract
In order to allow the preparation of labeled derivatives of the leukotriene B4 (LTB4) antagonist CP-195543 for the study and/or “visualization” of LTB4 receptors in in vitro and in vivo settings, we have synthesized an aminohexyl-containing analog (2) as a scaffold from which the requisite compounds can be prepared. The key reactions in the preparation of 2 include the DAST-mediated introduction of a difluoromethylene group in the presence of an azide and a Suzuki coupling between this highly functionalized benzoate and a chromanol-derived boronic acid.2-(3S,4R)-(3-Benzyl-4-hydroxychroman-7-yl)-4-(1,1-difluoro-7-methanesulfonamidoheptyl)benzoic acid (12), prepared from 2 by methanesulfonylation and saponification, is a potent LTB4 receptor antagonist but displays a high degree of non-specific binding.
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■ Syntheses of Melatonin and Its Derivatives
Masanori Somei,* Yoshikazu Fukui, Masakazu Hasegawa, Naoki Oshikiri, and Toshikatsu Hayashi
*Faculty of Pharmaceutical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan
Abstract
Two simple synthetic methods for melatonin are newly developed from tryptamine through intermediates, which are promising lead compounds for drug developing research. Novel chemical reactivities of melatonin in its bromi- nation, lithiation, and acylation are also reported.
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■ Synthesis and Structural Characterization of Palladium(II) Complex with (L)-3-Acetyl-5-benzyl-1-phenyl-4,5-dihydro-1,2,4-triazin-6-one Oxime. Part II
Ahmad S. Abushamleh, Mustafa M. El-Abadelah,* and Cäcilia M. Mössmer
*Chemistry Department, Faculty of Science, University of Jordan, Amman 11942, Jordan
Abstract
The synthesis and structural properties of the four-coordinate Pd(L)2 (4), where L is chiral 3-acetyl-5-benzyl-1-phenyl-4,5-dihydro-1,2,4-triazin-6-one oxime, (2), are described. Deep-red needles of 4 crystallize in the hexagonal space group P61. The crystallographic data reveal that the two oxime ligands are not symmetrically coordinated to Pd(II) ion, and the 4N-donor set comprises both oxime nitrogens, an amidrazone nitrogen and a hydrazone nitrogen. 1H-, 13C-NMR and FD-MS spectral data of 4 are consistent with its X-Ray molecular structure.
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■ Cyanoglycosylation Accompanied by Ring-Opening of Spirostanols
Akihiko Tobari, Hiroshi Miyamae, Akira Nagasawa, Junich Koyanagi, Masami Kawase, and Setsuo Saito*
*Faculty of Pharmaceutical Sciences, Josai University, Keyakidai 1-1, Sakado, Saitama 350-0295, Japan
Abstract
The reaction of 3-O-acetylsarsasapogenin (7), which has no hydroxyl group susceptible to glycosylation, with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (5) in the presence of a mixed catalyst, Hg(CN)2 and HgBr2, caused by cleavage the F-ring to give a 22-α-cyano-3,26-di-O-acetyl-5β-furostan derivative (8) and five monoglycosides (9-13) which were also products resulted from the cleavage of the F-ring of 7 accompanied by glycosylation. The trigger of the cleavage of the F-ring was speculated that a cyano anion generated from Hg(CN)2 used as catalyst attacked at C-22 of 7 from α-site to open the F-ring, then the six products were produced. The orientation of the attacking CN- group to C-22 of 7 was determinated on the basis of the X-Ray structure of 17.
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■ Synthesis of a Seco Analogue of Ardeemin
Esmeralda Caballero, Carmen Avendaño,* and J. Carlos Menéndez*
*Departamento de Química Orgánica y Farmacéutica, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain
Abstract
(1S,4S)-1-Indolylmethyl-4-methyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazaline-3,6-dione, a seco analogue of ardeemin, was synthesized in six steps from L-tryptophan methyl ester via an N-protected 2,5-piperazinedione and using an aza-Wittig reaction for the preparation of the quinazoline system. The final acid-promoted deprotection required tuning of the reaction conditions in order to minimize a side reaction involving loss of the indolylmethyl side chain.
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■ Benzotriazole-mediated [1,2]-Wittig Rearrangement. The Preparation of Homoalcohols from Ethers
Alan R. Katritzky* and Yunfeng Fang
*Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, U.S.A.
Abstract
α-(Benzotriazol-1-yl)alkyl benzyl ethers (6a-e) undergo [1,2]-Wittig rearrangement upon treatment with 2 equiv of organolithium reagents.
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■ Violides N-P, New Briarane Diterpenes from a Gorgonacean Briareum Sp.
Tetsuo Iwagawa,* Tetsushi Hirose, Keita Takayama, Hiroaki Okamura, Munehiro Nakatani, Matsumi Doe, and Kaoru Takemura
*Faculty of Science, Kagoshima University, Kagoshima 890-0065, Japan
Abstract
Three new briarane diterpenes, violides N-P, have been isolated from a Gorgonacean Briareum sp. and the structures elucidated. Violide N exhibited moderate cytotoxicity toward Vero and MDCK cells.
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■ Synthesis of Alkyl 1-(Substituted Pyridin-2-yl)-1H-1,2,3-triazole-4-carboxylates by ‘Ring Switching’ Transformation of 4-Oxo-4H-pyridino[1,2-a]pyrimidine-3-diazonium Tetrafluoroborates
Simon Recnik, Jurij Svete,* Anton Meden, and Branko Stanovnik*
*Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, 1000 Ljubljana, Slovenia
Abstract
Substituted 3-amino-4-oxo-4H-pyridino[1,2-a]pyrimidines (6, 7), available in 2 steps from methyl 2-benzyloxycarbonylamino-3-dimethylaminopropenoate (3) and 2-aminopyridines (1, 2), were diazotized into stable diazonium tetrafluoroborates (8, 9). Heating of diazonium salts (8, 9) with primary alcohols furnished alkyl 1-(substituted pyridin-2-yl)-1H-1,2,3-triazoles (11, 12) in 30-70% yields.
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■ O-Terpenoidal Coumarins from Clausena excavata
Hongping He, Yuemao Shen, Yineng He, Xiaosheng Yang, Weiming Zhu, and Xiaojiang Hao*
*Laboratory of Phytochemistry, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650204, China
Abstract
A new O-terpenoidal coumarin named excavacoumarin A (1) and a known one (2) were isolated from the leaves of Clausena excavata Burm. f. (Rutaceae) collected in Xishuangbanna, Yunnan. The structure of 1 was elucidated by spectroscopic analysis.
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■ Total Synthesis of (+)-Galanolactone
Masako Nozawa, Eriko Ono, and Hiroyuki Akita*
*School of Pharmaceutical Sciences, Toho University, 2-2-1, Miyama, Funabashi, Chiba 274-8510, Japan
Abstract
Regioselective monobenzylation of the chemoenzymatically prepared chiral decalin-type diol ((8aS)-6) via the benzylidene acetal ((8aS)-11) afforded the primary alcohol ((8aS)-7), from which total synthesis of (+)-galanolactone (1) was achieved and formal syntheses of (+)-(E)-8β(17),12-labddiene-15,16-dial ((+)-3) and (+)-coronarin E (4) were carried out.
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■ Studies on Crown Ether Cyanine Dyes
Weijun Ke, Hansheng Xu,* Xiufang Liu, and Xuehong Luo
*Department of Chemistry, Wuhan University, Wuhan 430072, China
Abstract
This review describes the syntheses and properties of crown ether cyanine dyes, in which several heterocycles (benzothiazole, benzoselenazole, benzimidazole, benzoxazole and benzotellurazole) containing different kinds of heteroatoms are annulated with benzocrown ether units.
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■ Synthesis of Substituted Quinazolin-4(3H)-ones and Quinazolines via
Directed Lithiation
Gamal A. El-Hiti*
*Department of Chemistry, Faculty of Science, Tanta University, Tanta 31527, Egypt
Abstract
Various quinazolin-4(3H)-ones and quinazolines were successfully lithiated using different lithiating reagents at low temperatures. Reactions of lithio reagents thus obtained with a variety of electrophiles afforded the corresponding substituted derivatives in very good yields.