Regular Issue

Vol. 53, No. 8, 2000

18 data found. 1 - 18 listed
Communication | Regular issue | Vol 53, No. 8, 2000, pp. 1669 - 1675
Published online:
DOI: 10.3987/COM-00-8904
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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Communication | Regular issue | Vol 53, No. 8, 2000, pp. 1677 - 1680
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DOI: 10.3987/COM-00-8932
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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Communication | Regular issue | Vol 53, No. 8, 2000, pp. 1681 - 1684
Published online:
DOI: 10.3987/COM-00-8940
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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Communication | Regular issue | Vol 53, No. 8, 2000, pp. 1685 - 1690
Published online:
DOI: 10.3987/COM-00-8947
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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Communication | Regular issue | Vol 53, No. 8, 2000, pp. 1691 - 1695
Published online:
DOI: 10.3987/COM-00-8955
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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Paper | Regular issue | Vol 53, No. 8, 2000, pp. 1697 - 1711
Published online:
DOI: 10.3987/COM-00-8875
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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Paper | Regular issue | Vol 53, No. 8, 2000, pp. 1713 - 1724
Published online:
DOI: 10.3987/COM-00-8919
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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Paper | Regular issue | Vol 53, No. 8, 2000, pp. 1725 - 1736
Published online:
DOI: 10.3987/COM-00-8930
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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Paper | Regular issue | Vol 53, No. 8, 2000, pp. 1737 - 1744
Published online:
DOI: 10.3987/COM-00-8936
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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Paper | Regular issue | Vol 53, No. 8, 2000, pp. 1745 - 1764
Published online:
DOI: 10.3987/COM-00-8937
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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Paper | Regular issue | Vol 53, No. 8, 2000, pp. 1765 - 1782
Published online:
DOI: 10.3987/COM-00-8942
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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Paper | Regular issue | Vol 53, No. 8, 2000, pp. 1783 - 1788
Published online:
DOI: 10.3987/COM-00-8945
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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Note | Regular issue | Vol 53, No. 8, 2000, pp. 1789 - 1792
Published online:
DOI: 10.3987/COM-00-8921
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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Note | Regular issue | Vol 53, No. 8, 2000, pp. 1793 - 1805
Published online:
DOI: 10.3987/COM-00-8925
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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Note | Regular issue | Vol 53, No. 8, 2000, pp. 1807 - 1810
Published online:
DOI: 10.3987/COM-00-8926
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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Note | Regular issue | Vol 53, No. 8, 2000, pp. 1811 - 1819
Published online:
DOI: 10.3987/COM-00-8963
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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Review | Regular issue | Vol 53, No. 8, 2000, pp. 1821 - 1837
Published online:
DOI: 10.3987/REV-00-532
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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Review | Regular issue | Vol 53, No. 8, 2000, pp. 1839 - 1868
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DOI: 10.3987/REV-00-535
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.

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18 data found. 1 - 18 listed