Special Issue

Rolf Huisgen's Special Issues, Vol. 40, No. 1, 1995

50 data found. 31 - 50 listedFirst Previous
Paper | Special issue | Vol 40, No. 1, 1995, pp. 241 - 248
Published online:
DOI: 10.3987/COM-94-S16
Iron Chelators of the Pyridoxal 2-Pyridyl Hydrozone Class. Part III. Ionisation and Conformational Characteristics of the Ligands

Prayong Doungdee, Shalom Sarel, Israel Ringel, Dan Gibson, Nipon Wongvisetsirikul, and Shelly Avramovici-Grisaru

*Department of Pharmaceutical Chemistry, Hebrew University School of Pharmacy, P. O. Box 12065, Jerusalem 91120, Israel

Abstract

pKa values of three biologically active iron chelators: pyridoxal 2-pyridyl hydrazone (PPH), 1-[N-methylpyridoxylidenium]-2-[2’-pyridyl]hydrazineiodide (MPH), 1-[N-ethoxycarbonylmethylpyridoxyidenium]-2-[2’-pyridyl]hydrazine (EPH) have been determined by a combination of ab initio calculations and pH-dependence of 13C nmr spectroscopy. In conformity with pyridoxal isonicotinoyl hydrazone (PIH), all ligands included in this study the pKa values invariably increase in the ordering: pyridinium protonation < pyridoxylidenium protonation < phenolate protonation < alkoxide protonation. Identical ordering was obtaind by ab initio calculations, based on STO-3G set. Mulliken population analysis indicates that the conformer of the lowest energy of PPH, (I), contains an internal 6-membered-ring H-bond. Rotation about C3 - C8 bond in (I), to yield conformer (IV), requires 8.8 kcal / mol, whereas its internal H-bonding (I → II) accounts for 5.8 kcal / mol. Protonation of (I) lowers significantly energies both of I → V (6.5 kcal), and I → VI (2.5 kcal) transitions.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 249 - 260
Published online:
DOI: 10.3987/COM-94-S18
New Method for Generation of Thiocarbonyl Ylides from Bis(trimethylsilylmethyl)sulfoxides and Their Application to Cycloadditions

Masaaki Aono, Yoshiyasu Terao, and Kazuo Achiwa*

*Schol of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan

Abstract

Thiocarbonyl ylides were generated by heating of bis(trimethylsilylmethyl) sulfoxides. Cycloadditions of the ylides in the presence of dipolarophiles proceeded smoothly to give di- or tetrahydrothiophenes.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 261 - 270
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DOI: 10.3987/COM-94-S21
Synthesis of a Simple Kainic Acid Analogue by Means of Carbamoylmethyl Radical Cyclization

Tatsunori Sato, Ken-ichiro Matsubayashi, Kazumi Yamamoto, Hiroko Ishikawa, Hiroyuki Ishibashi, and Masazumi Ikeda

*Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto 607-8414, Japan

Abstract

A new approach to (-)-(2S, 3R)-2-carboxy-3-pyrrolidineacetic acid (6) starting from D-serine is described. The key step is a radical cyclization of tert-butyl (S)-3-[2,2-dimethyl-N-[chloro(phenylthio)acetyl]oxazolidin-4-yl]-(E)-propenoate (15b), which gave tert-butyl (6S, 7R, 7aS)-5,6,7,7a-tetrahydro-3,3-dimethyl-5-oxo-6-phenylthio-1H,3H-pyrrolo[1,2-c]oxazol-7-ylacetate (16b) in a highly regio- and diastereo-selective manner. The compound (16b) was then converted into tert-butyl (4R, 5S)-5-(tert-butyldimethylsilyloxymethyl)-1-methoxycarbonyl-2-oxopyrrolidin-4-ylacetate (19) by standard chemical manipulations, which has already been transformed to 6.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 271 - 278
Published online:
DOI: 10.3987/COM-94-S22
1,3-Dipolar Cycloaddition of Nitrones and Nitrile Oxides to 5,5-Dimethyl-3-methylenepyrrolidine-2-thione

Lubor Fisera, Libuse Jaroskova, Iveta Matejkova and Heinz Heimgartner

*Department of Organic Chemistry, Slovak University of Technology, SK-812 37 Bratislava, Slovakia

Abstract

A simple synthesis of title compound (3) and a number of different cycloadditions are described. C-Aroyl- and C,N-diphenylnitrones react regio- and stereoselectively to the C=C exocyclic double bond of 3, to give only spirocycloadduct (10). On the other hand, C-phenyl-N-methylnitrone gives a mixture of diastereomeric spirocycloadducts (10) and (11). Nitrile oxides undergo 1,3-dipolar cycloaddition both to the exocyclic C=C and C=S double bonds with subsequent cycloreversion and formation of spiro-lactams (6). The appropriate spiro-thiolactams (8) were synthetized by treatment of 6 with Lawesson’s reagent.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 279 - 284
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DOI: 10.3987/COM-94-S25
Two New Xanthones from the Root Bark of Garcinia Subelliptica

Munekazu Iinuma, Hideki Tosa, Toshiyuki Tanaka, Fujio Asai, and Ryoyu Shimano

*Departmeny of Pharmacognosy, Gifu Pharmaceutical University, 6-1 Mitahora-higashi 5-chome, Gifu 502-8585, Japan

Abstract

From the root bark of Garcinia subelliptica, two new xanthones named subelliptenones C (1) and D (2) were isolated in addition to two known xanthones [12b-hydroxy-des-D-garcigerin (3) and globuxanthone (4)]. The structures were determined by analysis of nmr spectral data including 2D techniques.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 285 - 292
Published online:
DOI: 10.3987/COM-94-S27
Synthesis of Isoxazoles Bearing Methoxycarbonyl and Formyl Groups by 1,3-Dipolar Cycloaddition of Nitrile Oxides to Olefinic and Acetylenic Dipolarophiles

Francisco Fariña, M. Teresa Fraile, M. Rosario Martin, M. Victoria Martín, and Ana Martínez Guereñu

*Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain

Abstract

The 1,3-dipolar cycloadditions of benzo-, bromoformo- and acetonitrile oxides to enamino ester (1) and acetylenic esters (2, 3) afforded functionalized isoxazoles in moderate to good yields. Cycloadditions with the enamino ester (1) gave the corresponding methyl 5-dimethoxymethylisoxazole-4-carboxylate (7a-9a) as the sole regioisomer, whereas the reactions with acetylenic dipolarophiles (2, 3) were generally less selective and the regioselectivity depended significantly on the nature of the substituents of the dipole and the acetylenic ester.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 293 - 300
Published online:
DOI: 10.3987/COM-94-S30
Dimeric Murrayafoline A, a potential Bis-Carbazole Alkaloid: 'Biomimetic' Synthesis, Atropoisomer Separation, and Antimalarial Activity

Gerhard Bringmann, Alfons Ledermann and Guido François

*Institüte of Organic Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany

Abstract

The first total synthesis of a (potential) dimeric carbazole alkaloid is described. After an improved preparation of the monomeric building block, ‘biomimetic dimerization’ by oxidative phenolic coupling was best achieved with di-tert-butyl peroxide in chlorobenzene, leading to a highly selective formation of the 2,2’-coupled ‘dimer’, the parent framework of several naturally occurring dimeric carbazole alkaloids. For the atropoenantiomer analysis, a chromatographic procedure on a chiral phase was developed. Both the mono- and the dimeric phenolic carbazoles displayed in vitro antimalarial activity against Plasmodium falciparum.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 301 - 310
Published online:
DOI: 10.3987/COM-94-S31
Chiral Synthesis of a Pyrrolizidine Alkaloid, (-)-Heliotridane

Toshio Honda, Shin-ichi Yamane, Koichi Naito, and Yukio Suzuki

*Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan

Abstract

Chiral synthesis of the necic base, heliotridane has been achieved by employing a samarium diiodide-promoted regioselective carbon-carbon bond cleavage reaction of the γ-halo ester (17), as a key step.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 311 - 317
Published online:
DOI: 10.3987/COM-94-S33
Heterocycles by Cycloaddition. XII. Cycloaddition-Extrusion of a Mesoionic 1,3-Dithiolium-4-olate and a Mesoionic Oxazolium-5-olate with a Phosphirene. Formation of Six- and Five-membered Heterocycles

Tomoshige Kobayashi, Hidefumi Minemura, and Hiroshi Kato

*Department of Chemistry, Faculty of Science, Shinshu University, Asahi, Matsumoto 390-8621, Japan

Abstract

The reaction of a mesoionic dithioliumolate (6) with triphenylphosphirene (7) gave a cycloadduct (8). Pyrolysis of the cycloadduct (8) gave a 1,4-thiaphosphinine (11) and a thiophene (9). Acid treatment or photolysis of the cycloadduct (8) gave the thiophene (9) exclusively. The reaction of a mesoionic oxazolium-5-olate (12) and the phosphirene (7) gave a pyrrole (15) as the only isolable product.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 319 - 330
Published online:
DOI: 10.3987/COM-94-S34
Diastereoselective Synthesis of Exo-6-aryl-3-azabicyclo[3.2.0]heptane Derivatives by Intramolecular [2+2]Photocycloadditions of Diallylic Amines

Gerd Steiner, Rainer Munschauer, Gerhard Klebe, and Lorenz Siggel

*Central Laboratory of BASF Aktiengesellschaft, D-67056 Ludwigshagen, Germany

Abstract

N-Cinnamyl-N-allylamines (1) react upon irradiation with UV light via a photochemical [2+2] cycloaddition to give new exo-6-aryl-3-azabicyclo[3.2.0]heptanes (2) with high diastereoselectivity. A kinetic study as well as semiempirical quantum mechanical calculations support the proposed mechanism.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 331 - 347
Published online:
DOI: 10.3987/COM-94-S37
1,3-Dipolar Cycloadditions to Oxidopyraziniums

Nicholas D. Yates, David A. Peters, Philip A. Allway, Roy L. Beddoes, David I. C. Scopes, and John A. Joule

*Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.

Abstract

The dipolar cycloadditions of a range of dipolarophiles to 1,5-dimethyl- and 1-arylmethyl-5-methyl-3-oxidopyraziniums are described.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 349 - 355
Published online:
DOI: 10.3987/COM-94-S41
Steric Configuration and Reactivity of 2-Benzylidene-4-methyl-2H-1,4-bensoxazin-3(4H)-one

Piero Dalla Croce, Raffaella Ferraccioli, and Concetta La Rosa

*Dipartimento di Chimica Organica e Industriale, Centro C. N. R., V. Venezian 21 I-20133 Milano, Italy

Abstract

The reactivity of 2-benzylidene-4-methyl-2H-1,4-benzoxazin-3(4H)-one (1) towards N- and C-nucleophiles, nucleophilic and electrophilic alkenes, dienes and 1,3-dipoles was investigated. Nitrones (2) reacted with 1 giving through a regioselective process a mixture of the two diastereoisomeric spiro compounds (3) and (4) whose structure and relative steric configuration have been assigned on the basis of 1H and 13C nmr data.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 357 - 378
Published online:
DOI: 10.3987/COM-94-S44
Preparation of Either Enantiomer of 1,2-Diaminoalkane-2-phosphonic Acid Derivatives

Armido Studer and Dieter Seebach

*Laboratory of Organic Chemistry, Swiss Federal Institute ofTechnology (ETH), Universitatstrasse 16 CH-8092, Zurich, Switzerland

Abstract

Imidazolidine-derived phosphono esters (1,11) are prepared from t-butyl (R)-2-t-butyl-3-methylimidazolidin-4-one-1-carboxylate (Boc-BMI, A) by Michaelis-Arbuzov reactions of appropriate intermediates [the 5-bromo-Boc-BMI and the acetoxy derivative (10)]. Deprotonation (DBU/LiBr or LTMP/BuLi) and reaction with alkyl halides give gem, disubstituted heterocycles (3-7,12-17), some of which are converted to the corresponding 2-amino-2-aminomethylalkanephosphonic acids (8,9,18-21). One of the substitution reactions with P(OMe)3 occurs with migration of the heterosubstituent from the α-NBoc to the α-NMe position of the imidazolidine system (Scheme 4). A very surprizing reversal of the stereochemical course of alkylation is observed with the dimethyl imidazolidinephosphonate (11) upon going from the more reactive (MeI, BnBr, AllylBr) to the less reactive halides (Et-, Pr-, and BuI). The product structures are derived from three X-ray crystal structure analyses, by nmr comparison, and by chemical correlation.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 379 - 386
Published online:
DOI: 10.3987/COM-94-S47
1,3-Dipolar Cycloadditions of an Aziridine via Azomethine Ylide to 2-Methylpyridazin-3(2H)-ones

Francisco Fariña, M. Victoria Martín-Ramos, and Magali Romañach

*Instituto de Química Orgánica General, C. S. I. C., Calle Juan de Cierva, 3, 28006 Madrid, Spain

Abstract

The 1,3-dipolar cycloaddition of the azomethine ylide generated by thermal ring opening of dimethyl trans-1-(p-methoxyphenyl)aziridine-2,3-dicarboxylate (1) to 2-methylpyridazin-3(2H)-one (3) and its cyano (4) and ethylsulphonyl (5,6) derivatives have been carried out. The azomethine ylide (2) undergoes addition to the 4,5 C=C double bond of 2-methylpyridazinones (3-6) to afford pyrrolo[3,4-d]pyridazin-1(2H)-one derivatives.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 387 - 399
Published online:
DOI: 10.3987/COM-94-S49
Preparation of γ-Heterosubstituted α,β-Hexenolides and Their 1,3-Dipolar Cycloaddition to 2,3,4,5-Tetrahydropyridine 1-Oxide

Félix Busqué, Pau Cid, Pedro de March, Marta Figueredo and Josep Font

*Departament de Química, Universidad Autonoma de Barcelona, 08193 Bellaterra (Barcelona), Spain

Abstract

This paper describes the preparation of several γ-heterosubstituted α,β-hexenolides and their 1,3-dipolar cycloaddition to 2,3,4,5-tetrahydropyridine 1-oxide. In all these reactions the formed tricyclic cycloadducts arise exclusively from an exo transition state and the antifacial approach of the reactants is preferred.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 401 - 411
Published online:
DOI: 10.3987/COM-94-S60
Synthesis of Thiacrownophanes Exhibiting High Ag+ Selectivities on the Liquid-Liquid Extraction

Seiichi Inokuma, Atsushi Kobayashi, Reiko Katoh, Toshiaki Yasuda, and Jun Nishimura

*Department of Chemistry, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu 376-8515, Japan

Abstract

Thiacrownophanes (6-8) were prepared by means of intramolecular [2 + 2] photocycloaddition. Thiacrownophane (6) with two sulfur and three oxygen atoms showed the most efficient extractability toward Ag+ with high selectivity even if the extraction system did not contain any special lipophilic counter anion.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 413 - 424
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DOI: 10.3987/COM-94-S66
1,3-Dipolar Cycloaddition of Nitrile Oxides to 1,4-Naphthoquinone Derivatives

Francisco Fariña, M. Victoria Martín, Marta Muñoz, M. Carmen Paredes, and Raquel Rodoríguez

*Instituto de Química Médica, C. S. I. C., Calle Juan de Cierva, 3, 28006 Madrid, Spain

Abstract

The 1,3-dipolar cycloadditions of benzonitrile and bromoformonitrile oxides (4 and 5) to naphthoquinone derivatives (3) proceed across the C=C double bond to afford naphthoisoxazolinediones. In the reaction with benzonitrile oxide (4) the initial cycloadducts (6 and 7) were isolated in good yields. However, the cycloaddition of bromoformonitrile oxide (5) affords directly the corresponding aromatized naphthoisoxazolediones (10 and 11) in good yields.

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Paper | Special issue | Vol 40, No. 1, 1995, pp. 425 - 440
Published online:
DOI: 10.3987/COM-94-S73
Purification and Characterization of a Cytochrome P450 Enzyme from Pig Liver, Catalyzing the Phenol Oxidative Coupling of (R)-Reticuline to Salutaridine, the Critical Step in Morphine Biosynthesis

Tobias Amann, Peter H. Ross, Hoon Huh, and Meihart H. Zenk

*Lefrstuhl für Pharmazeutische Biologie, Universität München, Karlstr. 29, 80333 München, Germany

Abstract

The cytochrome P450 enzyme catalyzing the conversion of (R)-reticuline to salutaridine in the presence of cytochrome c reductase, NADPH and O2 was purified to homogeneity from pig liver and shown to be a highly regio- and stereoselective enzyme. This finding supports the view that the occurrence of morphine in mammals is of endogenous and not of dietary origin.

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Review | Special issue | Vol 40, No. 1, 1995, pp. 441 - 475
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DOI: 10.3987/REV-94-SR1
Transformations of Nitropyrimidines by Action of C-Nucleophiles

Vladimir L. Rusinov, Oleg N. Chupakhin, and Henk C. van Plas

*Department of Organic Chemistry, Ural State Technical University, Mira Str., 19, Ekaterinburg, 620002, Russia

Abstract

The addition of C-nucleophiles to 5-nitropyrimidines, to some of their [1,5-a]pyrazolo- or triazolo-annelated systems, and their subsequent ring transformations have been reviewed. The ring transformations involving the replacement of the N(3)-C(4)-C(5) fragment of the pyrimidine ring, the N(1)-C(5)-C(6), the N(1)-C(2)-N(3) or the N(1)-C(2) fragment by structural parts of different C-nucleophilic agents are summarized; possible pathways, involving these transformations are discussed

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Review | Special issue | Vol 40, No. 1, 1995, pp. 477 - 500
Published online:
DOI: 10.3987/REV-94-SR2
Cyclic Carboxylic Imide Structures as Structure Elements of High Stability. Novel Developments in Perylene Dye Chemistry

Heinz Langhals

*Institut für Organische Chemie, Universität München, Karlstrasse 23, D-80333 München, Germany

Abstract

Cyclic carboxylic imides are structure elements in aromatic heterocycles with high persistency. Their attachment to perylene leads to the perylene dyes; the synthesis and unique properties of the dyes are reported and discussed. An extension of the principle to other aromatics is made.

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