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. 20, No. 9, 1983
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■ Thio-Claisen Rearrangement of Troponoids
Hitoshi Takeshita, Kingo Uchida, and Hiroaki Mametsuka
*Instituete of Advanced Material Study, Kyushu University, 6-1, Kasuga-koen, Kasuga 816-8580, Japan
Abstract
Several 2-(allylthio)tropones and 2-(propargylthio)tropones gave 2,3-dihydro-(8H)-cyclohepta[b]thiophen-8-ones and (8H)-cyclohepta[b]thiophen-8-ones via a thio-Claisen rearrangement by heating above 180 °C. In cases of γ-substituted allyl derivatives, the results of rearrangement were poor; 2-(prenylthio)tropone gave isoprene by an elimination, similar to 2-(allyloxy)-tropones, while its 3,5,7-trimethyl homolog caused no reaction.
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■ 13C NMR Study of Annular Tautomerism of Azoles in the Solid State
Robert Faure, Emile-Jean Vincent, and José Elguero
*Laboratoire de Chimie Organique Physique, Facluté des Sciences et Techniques de Saint Jérôme, Université d’Aix-Marseille III, Avenue Escardille Normandie Niemen (Case 552), 13397 Marseille Cedex 13, France
Abstract
The 13C chemical shifts of 1,2,4-triazole, tetrazole, indazole, benzimidazole, and benzotriazole have been obtained from solid samples using the CP-MAS technique. They are discussed in connection with the annular prototropic tautomerism of these azoles and benzazoles. A case of functional tautmerism, that of benzoxazolidin-2-thione, and a case of non-prototropic tautmerism, that of 1-trimethylsilylbenzimidazole, are also studied.
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■ Substituent Effects on Proton Affinities: Through Bonds or through Space Mechanism?
Javier Catalán, Pilar Pérez, and José Elguero
*Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain
Abstract
INDO calculations of the protonation energies and lone pair orbital energies of twenty pyrazoles and twenty imidazoles have been carried out in order to ascertain the mechanism of the substituent effect. Methyl, cyano, fluoro, amino, and nitro substituents have been examined. The last one shows a special behaviour. The importance to optimize the geometry and the reasons for the anomaly shown by the nitro derivatives are discussed.
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■ A Synthesis of Pyrido[1,2-a]quinoxalines and Pyrido[1,2-a]pyrazines
Norio Kawahara, Takako Nakajima, Tsuneo Itoh, and Haruo Ogura
*Hokkaido College of Pharmacy, 7-1 Katsuraoka-cho, Otaru 047-02, Japan
Abstract
o-Phenylenediamines and 1,2-diamines reacted with dimethyl acetylenedicarboxylate (DMAD) to afford trimethyl 3-oxo-1,2,3,4-tetrahydroquinoxaline-Δ2,γ-aconitates and trimethyl 3-oxo-piperazine-Δ2,γ-aconitates which were converted to pyrido-[1,2-a]quinoxalines and pyrido[1,2-a]pyrazines, respectively, by thermal or photochemical reactions.
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■ The Synthesis of Spiro[5,6]-3-oxaundecan-7-one. Observation of a Specific Oxugen-directing Effect
Bradford P. Mundy, Youseung Kim, and Ronald J. Warnet
*Department of Chemistry, Montana State University, Bozeman, Montana 59717, U.S.A.
Abstract
The title compound was prepared by pinacol rearrangement, where a remote oxygenheteroatom gave specific orientation to the course of rearrangement.
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■ New Syntheses of Praziquantel: 2-(Cyclohexylcarbonyl)-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-one
Daniel Frehel and Jean-Pierre Maffrand
*Linge Hémobiologie, Sanofi Recherche, 195 route d’Espagne, 31036 Toulouse, France
Abstract
This paper describes two different synthetic pathways for praziquantel, a new broad spectrum schistosomicide and cestocide. Easy to apply on an industrial scale, they involve a selective reduction of 4-acyl-1-phenethylpiperazine-2,6-dione in 4-acyl-6-hydroxy-1-phenethylpiperazin-2 one, the cyclisation of which in acidic medium gives tricyclic compounds 2-acyl-1,2,3,6,7,11b-hexahydro-4H-pyrazin [2,1-a]isoquinolin-4-one.
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■ Regiospecific and Stereoselective Synthesis of E or Z-N-Allyl Pyrroles via Vinylphosphonium Salts
Russell J. Linderman and A. I. Meyers
*Department of Chemistry, Colorado State University, Fort Collins, CO 80523-1872, U.S.A.
Abstract
Reaction of N-sodiopyrrole with vinyltriphenyl phosphonium bromide and various aldehydes gives only N-allylpyrroles with generally very high Z-geometry. The same reaction using vinyltri-n-butylphosphonium bromide furnished N-allylpyrroles with moderate to high E-geometry.
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■ Structure of Mahuannin C, a Hypotensive Principle of Ephedra Roots
Yoshimasa Kasahara, Nobuyoshi Shinomiya, Chohachi Konno, and Hiroshi Hikino
*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan
Abstract
A new bisflavanol, mahuannin C, showing the hypotensive activity has been isolated from the crude drug “mao-kon”, the roots of Ephedra plants. The stereostructure of mahuannin C has been deduced as shown in formula I on the basis of chemical and physical evidence.
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■ Reaction of Ketenethioacetals with Carboxamides
Shinya Kohra, Yoshinori Tominaga, Yoshiro Matsuda, and Goro Kobayashi
*Faculty of Pharmaceutical Sciences, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
Reaction of methyl 2-cyano-3,3-bis(methylthio)acrylate (1a) with carboxamides in the presence of sodium hydride in a mixture of benzene and N,N-dimethylacetamide gave the corresponding displacement products of methylthio group, methyl 3-(N-alkyl or aryl)carbamoyl-2-cyano-3-(methylthio)acrylates (3a,b,c,d,e,f,g,h). Refluxing of 3 in methanol gave the corresponding cyclized product, 2-alkyl or 2-aryl-5-methoxycarbonyl-6-methylthio-4(3H)-pyrimidones (4). Compound 3a was allowed to react with amine(morpholine, benzylamine, cyclohexylamine, aniline) to give 4-(substituted amino)-4(3H)-pyrimidone derivatives (6a,b,c,d).
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■ The First Isolation of Isomeric α- and β-Phenylazoxypyridine-N-oxides
Erwin Buncel and Sam-Rok Keum
*Department of Chemistry, Queen’s University, Kingston, Ontario K6L 3N6, Canada
Abstract
The oxidation of 4-phenylazopyridine gives rise to the isomeric α- and β-4-phenylazoxypyridine-N-oxides, contrary to a previous literature report. 3-Phenylazopyridine similarly affords the respective α- and β-azoxy compounds but 2-phenylazopyridine yields only the α-azoxy product.
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■ Studies on the Synthesis of Heterocyclic Compounds. XII. Preparation of New Sulfur-containing Macrocycles
Carlo Anchisi, Loenardo Bonsignore, Luciana Corda, Antonio Maccioni, and Gianni Podda
*Istituto di Chimica Farmaceutica, Tossicologica ed Applicate, University of Cagliari, Via Ospedale 72, 09100 Cagliari, Italy
Abstract
A new series of macrocyclic sulfur-containing compounds have been prepared by treating 2-chloro-1,3,2-benzoxathiastibole with various diacyl chlorides.
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■ Pseudoesters and Derivatives. XVIII. The Reaction of 5-Methoxyfuran-2(5H)-one and Its 3-Halo Derivatives with Nitrogen and Sulphur Nucleophiles
Francisco Fariña, M. Victoria Martín, Félix Sánchez, M. Carmen Maestro, and M. Rosario Martín
*Instituto de Química Orgánica General, C. S. I. C., Calle Juan de Cierva, 3, 28006 Madrid, Spain
Abstract
The 5-methoxyfuran-2(5H)-ones 1 - 3 react with amines and thiols under basic catalysis at room temperature in tetrahydrofuran or carbon tetrachloride yielding the corresponding products of conjugate addition. The nucleophile enters preferentially from the side opposite to the OMe group.
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■ Facile Synthesis of 2-Amino-dihydro-4(1H)-pyrimidinone Derivatives: Cyclization of N-Substituted Guanidines with α,β-Unsaturated Esters
Yong Hae Kim and Nam Jin Lee
*Department of Chemistry, Korea Advanced Institute of Science and Technology, 373-1, Kusung-Dong, Yusung-Gu, Taejon, 305-701, Korea
Abstract
2-Amino-5,6-dihydropyrimidin-(1H)-4-one derivatives containing guanidine moiety (3) have been synthesized in excellent yields by the cyclization of free N-substituted guanidines with α,β-unsaturated esters such as methyl acrylate and methyl methacrylate derivatives under mild conditions.
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■ Chemistry of Nuphar Alkaloids. Part IV. Hofmann Degradation of C15 and C30 Methiodides
Jacek Cybulski, Krystyna Wojtasiewicz, and Jerzy T. Wróbel
*Department of Chemistry, University of Warsaw, Pasteura St.1, 02-093 Warsaw, Poland
Abstract
Hofmann degradation of isomeric thiobinupharidine (TBN) monomethiodides is described. The structure and stereochemistry of the products obtained have been proposed on the basis of 1H nmr end 13C nmr spectra. Hofmann degradation products of DN- and 7EDN-methiodides have been used as model compounds.
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■ N-Polyazolymethanes. IV. Reaction of Benzotriazole with Methylene Chloride and Chloroform under Phase Transfer Conditions
Luis Avila, José Elguero, Sebastián Juliá, and José M. del Mazo
*Instituto de Química Orgánica General, C. S. I. C., Calle Juan de Cierva, 3, 28006 Madrid, Spain
Abstract
Six out of seven possible products obtained from benzotriazole and methylene chloride or chloroform have been isolated and characterized. An intermediate, 2-dichloromethylbenzotriazole, has been isolated for the first time. The relative amounts of the different isomers follow an (a+b)n relationship (n = 2 or 3). Proton and carbon-13 nmr spectroscopy and mass spectrometry have been used to identify the N,N’-bis-and N,N’,N”-trisbenzotriazole derivatives.
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■ Synthesis of 2-Substituted 3-(2-benzo[b]thienyl)- or 3-(2-Thienyl)-3-methylthioacrylonitriles
Shinichi Fukuda, Yoshinori Tominaga, Yoshiro Matsuda, and Goro Kobayashi
*Faculty of Pharmaceutical Sciences, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
Reaction of methyl benzo[b]thiophene-2-dithiocarboxylate(2) with active methylene compounds (malononitrile, methyl cyanoacetate and cyanoacetamide) in the presence of sodium hydride followed by methylation with dimethyl sulfate gave the corresponding 2-substituted 3-(2-benzo[b]thienyl)-3-methylthioacrylonitriles (2-CN, 2-COOCH3, and 2-CONH2) (3a, b, c) in good yields. Compounds 3a and 3b were alternatively synthesized by the reaction of 2-lithiobenzo[b]thiophene with ketenethioacetal [bis(methylthio)methylenemalononitrile and methyl bis (methylthio)methylenecyanoacetate]. Similarly, 2-cyano-3-methylthio-3-(2-thienyl)acrylonitrile (6) was also prepared from methyl thiophene-2-dithiocarboxylate(5). Methyl dithiocarboxylates (2 and 5) were prepared by the reaction of 2-lithio derivatives of 1 and 4 with carbon disulfide followed by methylation with dimethyl sulfate in good yields.
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■ A Short Step Synthesis of Lespedamine
Masanori Somei, Haruhiko Sato, and Chikara Kaneko
*Faculty of Pharmaceutical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan
Abstract
A convenient synthetic method for 1-hydroxy-, 1-methoxy-, and 1-acetoxy-2-oxindole was disclosed starting from methyl 2-nitrophenylacetate. A five-step synthesis of lespedamine was achieved utilizing this method.
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■ Synthesis of Some 3-Oxo-2-phenyl-6,7-dihydro-2H-pyrano[4,3-c]pyrazole Derivatives
Bernard Chantegrel, Abdel Ilah Nadi, and Suzanne Gelin
*Département de Biochimie, Laboratoire de Chimie Organique, Institut National des Sciences Appliquées, 20 Avenue Albert Einstein 69621 Villeurbanne Cedex, France
Abstract
Acylation reaction of 3-(2-methyl-1-propenyl)-1-phenyl-2-pyrazolin-5-one provides a route to 6,6-dimethyl-3-oxo-2-phenyl-6,7-dihydro-2H-pyrano[4,3-c]pyrazole derivatives.
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■ Synthesis of 5-Fromyl-2,4,6-trisubstituted Pyrimidines
Thomas J. Delia and Ronald Otteman
*Department of Pharmacology, John Curtin School of Medical Research, Australian National University, GPOBox 334, Canberra, ACT 2601, Australia
Abstract
A facile synthesis of 5-formyl-2,4,6-trisubstituted pyrimidines bearing amino and hydroxy groups is described. The Vilsmeier reagent, under mild conditions, gives good yields of products without accompanying chlorination of hydroxy groups.
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■ The Reaction of 3-(1-Imidazolyl)-2-alken-1-ones with Organometallic Compounds
Choji Kashima, Tadakuni Tajima, and Yoshimori Omote
*Department of Chemistry, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki, 305-8571, Japan
Abstract
In the reaction with organometallic compounds, 3-(1-imidazolyl)-2-alken-1-ones (1) gave both 1,2- and 1,4-addition products in a comparable ratio. This fact showed that the chemical properties of 1 were analogous to those of 3-phenyl-2-alken-1-ones (2) and 3-amino-2-alken-1-ones (3).
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■ Arene Syntheses by Extrusion of Heteroatoms from 7-Heteroatom-bicyclo[2.2.1]heptene Systems
Henry N. C. Wong, Tang-Kei Ng, and Tai-Yuen Wong
*Department of Chemistrym The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, Hong Kong
Abstract
Thermal and chemical extrusion of bridges containing O, S, N, P, Si, Ge, Sn, Co, Ir and Rh from the 7-heteroatom-bicyclo[2.2.1]heptenes are potentially important methods for constructing arenes with appropiate substituents.