HETEROCYCLES
An International Journal for Reviews and Communications in Heterocyclic ChemistryWeb Edition ISSN: 1881-0942
Published online by The Japan Institute of Heterocyclic Chemistry
Special Issue
Alan R. Katritzky's Special Issues, Vol. 37, No. 2, 1994
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■ Synthesis of Novel Heterocyclic Clefts Derived from Tetracyclo[6.3.0.04,11.05,9]undecane-3,6-dione and Tricyclo[6.3.0.02,6]ubdecane-3,11,dione
Makhluf J. Haddadin,* Yanjun Wang, Svetlana Frenkel, Simon G. Bott,* Lei Yang, Paul S. Braterman,* Carol Carvallo, Alan P. Marchand,* William H. Watson,* Ram P. Kashyap, Mariusz Krawiec, and Susan A. Bourne
*Department of Chemistry, University of North Texas, Denton, TX 76203-0068, U.S.A.
Abstract
New molecular clefts (6a-6c), (9a). and (9b) have been prepared via base promoted reactions of 3,6-diaryl-1,2,4,5-tetrazines with tetracyclo[6.3.0.04,11.05,9]undecane-3,6-dione (1) and with tricyclo[6.3.0.02,6]undecane-3,11-dione (10), respectively. Compounds of this type are of interest as a potential new class of host molecules for use in host-guest complexation studies (i.e., inclusion phenomena and molecular recognition). The results obtained via studies of the solution electrochemistry of systems (6a-6c), (9a), and (9b) afforded no evidence for the existence of any significant electronic interaction between opposing “arms” in these molecular clefts.
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■ Preparation and Steric Structure of Tricyclic and Tetracyclic Saturated or Partially Saturated 1,3-Heterocycles Containing a Saturated Isoindolone Moiety
Géza Stájer,* Ferenc Csende, Gábor Bernáth, and Pál Sohár
*Institute of Pharmaceutical Chemistry, Albert Szent-Györgyi Medical University, POB 121, H-6701 Szeged, Eötvös u. 6, Hungary
Abstract
From cis-2-(p-methylbenzoyl)-1-cyclohexanecarboxylic acid (1) and diendo-3-(p-methylbenzoyl)bicyclo[2.2.1]heptane-2-carboxylic acid (2) with α,ω-alkylenediamines, the perhydroimidazo[2,1-a]isoindolone (3), the corresponding perhydropyrimido and perhydrodiazepino derivatives (4) and (5) and their methylene-bridged tetracyclic analogues (6-8) were obtained. Compound (1) and ethanolamine yielded the perhydro-1,3-oxazolo[2,3-a]isoindolone derivative (9), while 1 with 3-amino-1-propanol or 2-aminoethanethiol gave the homologous saturated 1,3-oxazino derivative (10) and thiazoloisoindolone derivative (11), respectively. On boiling in xylene, 9 was transformed to the hydroxyethylisoindolone (12). From 1 and o-phenylenediamine, diamine, the trans-isoindolo[2,1-a]benzimidazoled erivative (13) was formed, while 1 and o-aminothiophenol gave the partly saturated cis-benzthiazole analogue (14).
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■ Synthesis of New Bis(indazol-1-yl)phenylmethanes
M Carmen López, Rosa M Claramunt, and Paloma Ballesteros*
*Departamento de Química Orgánica y Biologiá, Faclutade de Ciencias, UNED, Senda del Rey 9, E-28040 Madrid, Spain
Abstract
Synthesis and spectroscopic characterization of new bis(indazol-1-yl)fluoro- or nitrophenylmethanes are reported. They have been prepared by reaction of indazole and 3-methylindazole with ortho-fluoro-, para-fluoro- and para-nitrobenzaldehydes in the presence of ZnCl2 and NiCl2.
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■ Concise Synthesis of 7,8-Dimethoxyisochroman-3-one: Formal Synthesis of Berberine
Hisashi Isii,* Mayumi Ozawa, Shuji Ohta, Takashi Harayama, and Tsitomu Ishikawa
*Faculty of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
Abstract
7,8-Dimethoxyisochroman-3-one (2), a synthetic precursor for berberine, was concisely synthesized from 4-formyl-7-methoxy-2-methylbenzo[b]furan (3), which had been readily available from isovanillin through the CsF-mediated Claisen rearrangement of the corresponding propargyl ether.
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■ Syntheses of Indolyl-4(3H)-quinazolinones
István Hermecz,* József Kökösi, Benjamin Podányi, and György Szász
*CHINOIN Pharmaceutical and Chemical Works Ltd., P. O. Box 110, H-1325 Budapest, Hungary
Abstract
2-(1H-Indol-2-yl)-4(3H)-quinazolinones (10,11) and 2-(2-ethoxycarbonyl-1H-indol-3-yl)-4(3H)-quinazolin-4-one (15) are prepared by the Fischer indolization of 2-(1-phenylhydrazonoalkyl)- (8,9) and 2-(2-phenylhydrazono-2-ethoxycarbonylethyl)-4(3H)-quinazolinone (14), respectively, by heating in PPA. When 2-phenylhydrazone derivative (14) is heated in 85% phosphoric acid at 180°C, besides indolization ester hydrolysis and decarboxylation also occurred to yield 2-(1H-indol-3-yI)-4(3H)-quinazolinone (16). The 3-(1H-indol-3-yl)-4(3H)-quinazolinone (24) is prepared either from the isomeric 3-indolyl derivatives of anthranilamide (21,23) by heating in 98% formic acid, or in “one pot” procedure from 2-[1-(N-methyl-N-phenylamino)ethyl]-4(3H (17) by heating in 98% formic acid in the presence of a few drops of conc. hydrochloric acid. The reaction mechanism is discussed.
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■ Trifluoromethylated Pyrimidines Starting from β-Trifluoroacetyl-lactams, -lactone and -cyclanone
Jean-Philippe Bouillon, Vincent Bouillon, Chantal Wynants, Zdenek Janousek, and Heinz G. Viehe*
*Laboratoire de Chimie Organique de Synthèse, Université Catholique de Louvain, Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
Abstract
A synthesis of trifluoromethylated pyrimidines from β-trifluoroacetyllactams and -benzolactams is accomplished by reaction with benzamidine as bisnucleophile. This condensation is also extended to cyclic trifluoromethylated 1,3-diketones and 3-aroyl-2-pyrrolidinones.
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■ Studies on the Double Mannich Condensation Reaction of o-Phthlaldehyde with p-Substituted Anilines in the Presence of 1,2,3-1H-Benzotriazole
Ichiro Takahashi,* Mikio Tsuzuki, Hiroshi Yokota, Hidehiko Kitajima, and Kimio Isa
*Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Fukui University, Bunkyo, Fukui 910, Japan
Abstract
The double Mannich condensation reaction in acetonitrile at room temperature has been investigated. In the condensation reaction of o-phthalaldehyde (1) with p-toluidine (2a; 1 equiv.) in the presence of. 1,2,3-1H-benzotriazole (Bt-H), the use of 3 equiv. of Bt-H afforded Bt-substituted isoindoline derivative (4a) exclusively for 8 h, and the use of 4 equiv. of Bt-H did for 4 h; further increment of reaction time induced the dissociation of Bt-H from 4a to give 2H-isoindole derivative (5a). On the other hand, when methyl p-aminobenzoate (2b) was used instead of 2a, the rate of the formation of isoindoline (4b) increased as the amount used of Bt-H was large (2 fi 3 fi 4 equiv.). Different from the 2-(p-tolyl) counterpart, the increment of the reaction time did not induce the dissociation of Bt-H to afford 2H-isoindole derivative (5b).
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■ One-Pot Synthesis of Tropocoronands Having Heteroatoms in Linker Chains and Related Podands
Kimio Shindo,* Hidetsugu Wakabayashi, Hiroshi Miyamae, Sumio Ishikawa, and Tetsuo Nozoe
*Department of Chemistry, Faculty of Science, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan
Abstract
Treatment of benzo[b]cyclohepta[e][1,4]oxazine (4) with 1.2 equiv. of dipropylenetriamine (5a) in ethanol at 80°C gave 6,7,8,9,11,12,13,20,21,22,23,25,26,27-tetradecahydrodicyclohepta[b,m][1,4,8,12,15,19]hexaazacyclodocosine (7a). Similar reactions of 4 with N,N-bis(3-aminopropyl)methylamine (5b), bis(3-aminopropyl) ether (5C), 1,2-bis(2-aminoethoxy)ethane (6b), and cystamine (6c) afforded similar tropocoronands (7b, 7c, 8a, and 8b), respectively, while the reactions of 4 with an excess of these amines gave the corresponding tropopodands (11a, 11b, 11c, 12a, and 12b). The reaction of 4 with diethylenetriamine (6a) yielded tricyclic compound (10) via bicyclic pyrazino compound (9). A single-crystal X-ray diffraction analysis of the nickel(II)-complex (13) obtained from 7a was made.
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■ Synthesis of 6-Methylisoquinolino[7,8-a]quinolizinium Salt: Efficient Synthesis of 2-(2-Arylvinyl)quinolizinium Salts by Knoevenagel Condensation Using Acetonitrile as a Solvent and the Photocyclization
Kiyoshi Sato, Koji Kano, Takuya Yafune, Mitsuhiko Hida, Sadao Arai,* and Takamichi Yamagishi
*Department of Industrial Chemistry, Faculty of Technology, Tokyo Metropolitan University, 1-1, Minami-ohsawa, Hachioji, Tokyo 192-0364, Japan
Abstract
In the Knoevenagel condensation of 2,3-dimethylquinolizinium salt with a wide variety of aromatic aldehydes in the presence of piperidine, the use of acetonitrile as a solvent gave excellent yields (77-100 %) of 2-(2-arylvinyl)-quinolizinium salts. In the condensation using methanol the yields were low because active bis(1-piperidino)arylmethane derived from aldehyde and piperidine changed to inactive aryl(methoxy)-1-piperidinomethane, The photocyclization of 2-[2-(4-pyridyl)vinyl]quinolizinium salt led to 6-methylisquinolino[7,8-a]quinolizinium salt.
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■ Generation and Diles-Alder Reactions of N1-Substituted Pyrazole-4,5-quinodimethanes
George E. Mertzanos, Nicholas E. Alexandrou,* Constantions A. Tsolerides, Sophia Mitkidou, and Julia Stephanidou-Stephanatou*
*Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, P.O.B. 103, GR-540 06 Thessaloniki, Greece
Abstract
The cycloaddition of o-quinodimethanes (9-11) generated in situ from the 4,5-bisbromomethylpyrazole derivatives (6-8), with several dienophiles leads to the formation of the cycloadducts (12-20). These Diels-Alder reactions are also examined on the basis of some AM1 calculations.
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■ Reaction of 1-Substituted Pyrroles with N-Fluorodibenzensulfonimide: Effect of Halogen on Electrophilic Substitution by Addition-Elimination
Michael De Rosa* and Vijay Rai Marwaha
*Department of Chemistry, The Pennsylvania State university, Delaware Country Campus, 25 yearsley Mill road, Media, PA 19063, U.S.A.
Abstract
The reaction of 1-substituted pyrroles (1-methyl, 1-ethyl and 1-phenyl) with N-fluorodibenzenesulfonimide (NFSi) gave N-(1-substituted 1H-pyrrol-2-yl)dibenzenesulfonimides as products by addition elimination. Defluorination of NFSi was the only competing reaction. In contrast the reaction of 1-t-butylpyrroie with NFSi gave a mixture of fluoropyrroles. This is attributed to a steric interaction between the t-butyl group and the phenyl groups on NFSi. N-Chlorodibenzenesulfonimide was found to dechlorinate under all conditions studied and it was not possible to compare its reactivity with that of NFSi. The results of this study support our hypothesis that the observation of addition-elimination in pyrroles is related to the Π-electron donating ability of the halogen initially introduced into the ring.
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■ The Photo-Deoxygenation of Heterocyclic N-Oxides
Elisa Fasani, Atef M. Amer, and Angelo Albini*
*Institute of Organic Chemistry, v.Giuria 7, 10125 Torino, Italy
Abstract
2-Methoxy and 2-nitrophenazine 10-oxide are deoxygenated by irradiation in the presence of triethylamine, 2,3-dimethyl-2-butene and triethylphosphite via electron transfer to the singlet excited state, as shown by the comparison of reaction quantum yield and fluorescence quenching. 1,4-Dimethoxybenzene quenches the singlet, but causes no deoxygenation. The same mechanism operates in the photoreduction of benzo[c]cinnoline 5-oxide, but it is too slow to compete efficiently with the rearrangement in the case of quinoline 1-oxide. The photo-deoxygenation of the boron trifluoride ground state complexes of these substrate is in every case unefficient.
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■ A Facile Synthesis of N-(2- and 4-Pyridyl)indoles
Koh-ichi Seki,* Kazue Ohkura, Masanao Terashima, and Yuichi Kanaoka
*Faculty of Pharmaceutical Scicences, Higashinihonngakuen University, 1757 Kanazawa, Toubetu-cho, Ishikari-gun, Hokkaodo 061-0212, Japan
Abstract
The reactions of the sodium salts of indoles with 2- and 4-fluoropyridines afforded the corresponding N-pyridylindoles in good yields, whereas the reaction with 3-fluoropyridine gave no coupling product.
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■ Bis(iminophosphorane)-mediated 1,2,4-Triazoloannulation on Imidazole and Benzimidazole Rings. Preparation of Imidazo[1,2-b]-1,2,4-triazoles and 1,2,4-Triazolo[1,5-a]benzimidazoles
Pedro Molina,* Enrique Aller, and Angeles Lorenzo
*Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, Campus de Espinardo, E-30071, Murcia, Spain
Abstract
Aza Wittig-type reactions of bis(iminophosphoranes) derived from 1,2-diaminoimidazole and 1,2-diaminobenzimidazole with isocyanates and aroyl chlorides afforded imidazo[1,2-b]-1,2,4-triazoles or 1,2,4-triazolo[1,5-a]benzimidazoles, respectively.
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■ Synthesis of a Multidentate Furan, Ester/Amido, Thioether and Polyether Containing Macrocycles
Pedro Molina,* Alberto Tárraga, and Carmen Ibáñez
*Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, Campus de Espinardo, Campus de Espinardo, E-30071, Murcia, Spain
Abstract
A synthethic route to tetrafuran-containing macrocycles, which allows for variation in the cavity size, is described using 5,5’-(thiodimethylene)-bis(2-furoyl chloride) as heterocyclic building block.
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■ Preparations and Antileukemic Activity of Congeners of Tropoloisoquinoline Alkaloids from Abuta concolor
Hideji Itokawa,* Kouji Matsumoto, Hiroshi Morita, and Koichi Takeya
*Department of Pharmacognosy, School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
Antileukemic tropoloisoquinoline alkaloids, pareirubine A (1) and grandirubrine (2), at first have been isolated from Abuta concolor (Menispermaceae). Methylation of 1 and 2, existing in solution as a mixture of tautomers gave the corresponding four methyl derivatives (3 - 6). Thioimerubrine (7) and thioisoimerubrine (8) were prepared by the nucleophilic substitutions of the methoxyl groups at C-11 and -10, respectively. Acetylation of 1 and 2 produced the corresponding mono-acetyl tautomers (9 and 10). Antileukemic activity of these derived tropoloisoquinoline alkaloids is also reported.
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■ Formation of (N-Heteroaryl)heteroarymethanamines from Heteroaromatic Aldehydes and Heteroaromatic Amines
Giuseppe Musumarra* and Caterina Sergi
*Dipartimento di Scienze Chimiche, Università di Catania, Viale A. Doria 6, I-95125 Catania, Italy
Abstract
The reactions of heteroaromatic aldehydes with heteroaromatic amines show significant differences depending on the heteroaromatic moieties present both in the aldehydes and in the amines, giving imines (3) or [bis-(heteroarylamino)methyl]arenes (5). The direct formation of (N-heteroaryl) heteroarylmethanamines (4) is achieved by the Leuckart-Wallach reaction. Reaction conditions for the formation of amines (4) by NaBH4 reduction of imines (3) are also reported.
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■ Relative Polarity of 1,3-Dioxane and 1,4-Dioxane Studied by the Reaction Field Theory and via Computer Simulations
Michel Luhmer, Marie-Louise Stien, and Jacques Reisse*
*Service de Chimie Organique, Faculté des Sciences Appliquées (CP165), Université Libre de Bruxelles, 50 Avenue F. D. Roosevelt, 1050 Brussels, Belgium
Abstract
We show that neither the dipole moment of a molecule nor the static dielectric constant of a solvent are satisfactory descriptors of polarity. According to the usual definition of molecular polarity, 1,3-dioxane is polar while 1,4-dioxane is not. The electric fields at the center of a 1,3-dioxane molecule dissolved in 1,4-dioxane and in 1,3-dioxane (pure liquid) were estimated by means of Monte Carlo statistical mechanics simulations and were found to be similar. This led us to emphasize and discuss one aspect of the limitations of the reaction field theory. Finally, we make use of the relationship between the polarity of solvent and the magnetic relaxation rate of dissolved monoatomic 131Xe to corroborate our conclusions. The relaxation rates of 131Xe dissolved in 1,3-dioxane and 1,4-dioxane were measured and were also found to be similar.
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■ Reaction of Tetrahydro-β-carboline-1-carboxylic Acid with Isocyanates and Isothiocynates. Synthesis of 1-Alkyl- or Arkylcarbomoyl-β-carbolines
María L. López-Rodríguez,* Ma José Morcillo, Pedro J. Gil, Ma Luisa Rosado, and Ma Paz Ventura
*Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain
Abstract
The reaction of (±)- 1,2,3,4-tetrahydro-β-carboline-1-carboxylic acid (8) with alkyl and aryl isocyanates formed the corresponding tetrahydro-β-carboline-hydantoin ring systems (7). However the reaction of 8 with isothiocyanates provided 2-alkyl- or arylthiocarbamoyl-1,2,3,4-tetrahydro-β-carbolines (9). The oxidation of 7 with selenium dioxide or dichlorodicyano-p-benzoquinone gave 1-substituted β-carbolines (10) related to β-carboline alkaloids.
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■ X-Ray Crystal Structure of Racemic 1,1',3,3'-Tetramethylleucoisoindigo and Rotational Isomer
Tetsuo Suyama, Takeshi Kato, Yutaka Morita,* and Hiroshi Miyamae
*Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japana
Abstract
The crystal structure of racemic 1,1’,3,3’-tetramethylleucoisoindigo was determined by X-ray analysis. The conformation in solid state thus obtained was + sc taking 3- and 3’-methyl groups as fiducial groups.
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■ Ozonolysis of Substituted Isoxazoles
Choji Kashima,* Katsumi Takahashi, and Akira Hosimi*
*Department of Chemistry, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki, 305-8571, Japan
Abstract
The ozonolysis of substituted isoxazoles was investigated. The ozonolysis rates and the products were dependent on the site of the substituent group on isoxazole ring. The reaction mechanism of the ozonolysis of isoxazoles was also proposed.
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■ A Relative of Pummerer's ketone as a Source of Morphine Analogues
John M Cave, Richard M Scrowston,* Peter D. Kennewell, and Robert Westwood
*School of Chemistry, The University, Hull HU6 7RX, U.K.
Abstract
An analogue (3) of Pummerer’s ketone has been prepared in low yield by intermolecular oxidative coupling of methyl 4-hydroxyphenylacetate. Its key structural feature is the presence in the 9b-position of a CH2CO2Me group. Conjugate addition of hydrogen cyanide to the αβ-unsaturated ketone system inserts in the 1-position a cyano group trans to the 9b-substituent. Suitable protection of the 3-oxo group, followed by reduction of the 1-cyano group affords a lactam (9), which may be regarded as an analogue of morphine, in which ring B has been ruptured.
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■ Ring-Chain Tautomerism and Crystal Structure of Some 1,3-Oxazacyclanes, and the Electrophilic Substitutent Constants for Some Heteroaryl Groups in Solution and in the Gas-Phase
Ferenc Fuelöp,* Reijo Sillampää, Martti Dahlqvist, Kalevi Pihlaja,* and Pirjo Vainiotalo*
*Department of Chemistry, University of Turku, FIN-20500 Turku, Finland
Abstract
In principle, the ring-chain tautomeric ratios of a number of 2-heteroaryl-substituted oxazolidines and tetrahydro-1,3-oxazines are well suited for determination of the Hammett-Brown σ+ constants of heteroaryl substituents such as 2-furyl, 3-furyl, 3-thienyl and 2-pyrrolyl in CDCl3 solution and in the gas phase. However, a number of factors, and especially hydrogenbonding, can change the monomeric character of either the ring or the chain form (or both), leading to deviations from the ideal σ+ values. X-Ray analysis has demonstrated the chain structures of the products of the reactions of L-(-)-norpseudoephedrine and (±)-trans-2-aminomethylcyclohexanol with pyrrole-2-carboxaldehyde.
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■ A Simple Approach to Pyrimidine and Quinazoline Derivatives by [4+2] Cycloaddition of 1,3-Diazadienes and Enamines
José Barluenga,* Miguel Tomás, Alfredo Ballesteros, and Luis A. López
*instituto Universitario de Química Organometálica "Enrique Moles", Facultad de Química, Universidad de Oviedo, 33071- Oviedo, Spain
Abstract
The reaction of 2-trimethylsilyloxy- (1) and 2-trimethylsilylthio-1,3-diazabutadienes (2) with enamines derived from aliphatic aldehydes leads regio and stereoselectively to substituted tetrahydropyrimidin-2(1H)-ones (3) and thiones (4) in high yields. Extension of this cycloaddition to cyclic enamines, e.g. derived from cyclohexanone, leading to quinazoline derivatives (9-10) is also described. These heterocycles undergo hydrolysis and dehydration to 3,4-dihydropyrimidine (7-8) and 3,4,5,6,7,8-hexahydroquinazoline (11-12) derivatives.
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■ Regio- and Stereoselective Addition of Nucleophiles to 1-Phenoxycarbonyl-2,3-dihydropyridinium Salts
Daniel L. Comins,* Geewon Chung, and Michael A. Foley
*Department of Chemistry, College of Physical and Methematical Sciences, North Carolina State Univesity, P. O. Box 8204, Raleigh, NC 27695-8204, U.S.A.
Abstract
Several 2-alkyl-l-phenoxycarbonyl-δ3-piperidines were prepared by the addition of alkylzinc iodides to dihydropyridinium salt (9). The treatment of 4-hydroxy-2-methyl-1-phenoxycarbonyl-1,2,3,4-tetrahydropyridine (12) with allylhimethylsilane in the presence of a variety of Lewis acids was studied and found to give cis- and trans-2-6-dialkyl-δ3-piperidines (14) and (15) in moderate to good yield. Among the Lewis acids studied, stannyl chloride gave the best yield with good stereoselectivity (84:16) favoring the cis-isomer (14). The analogous reaction of the 4-methoxy derivative (13) with organozinc reagents was examined and found to give the cis-isomers (17) as the major products. Using this methodology, the cis-piperidine alkaloid, (±)-dihydropinidine, was prepared in six steps from 4-methoxypyridine.
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■ N-Hydroxyamide-containing Heterocycles. Part3. The Ring Transformation of 1-Benzyloxy-2(1H)-pyrimidinones into 2-Isoxazolines with Hydroxylamine
Akira Katoh,* Junko Ohkanda, Atsushi Tamura, Yuji Yoshiike, and Keiryo Mitsuhashi
*Department of Industrial Chemistry, Faculty of Engineering, Seikei University, Musashino-shi, Tokyo 180-8633, Japan
Abstract
N-Benzyloxyurea was treated with various β-diketones in the presence of sulfuric acid in EtOH to give the corresponding 1-benzyloxy-2(1H)-pyrimidinones. 1-Benzyloxy-2(1H)-pyrimidinones underwent the ring transformation with hydroxylamine to afford new 5-N-(benzyloxy)ureaattached 2-isoxazolines in addition to known isoxazoles. The MNDO molecular orbital calculation of 1-benzyloxy-4,6-dimethyl-2(1H)-pyrimidinone and the reaction mechanism are also discussed.
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■ Isolation of New Chlorinated Regioisomers of Mono N-Substituted Uracil Derivatives and Synthesis of 3-Substituted 8-Phenylpyrimido[5,4-e]-1,2,4-triazine-5,7(6H,8H)-diones
Tomohisa Nagamatsu,* Hirofumi Yamasaki, and Fumio Yoneda
*Faculty of Pharmaceutical Science, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan
Abstract
A variety of fervenulin type products, 3-substituted 8-phenylpyrimido[5,4-e]-1,2,4-triazine-5,7(6H,8H)-diones (18a-i), were synthesized by nitrosative or nitrative cyclization of the aldehyde hydrazones (17a-i) derived from 6-(1-methylhydrazino)-1-phenyluracil (16) with aliphatic as well as aromatic aldehydes. The compound (16) was prepared by the reaction of 6-chloro-1-phenyluracil (8) with methylhydrazine. In addition, not only the precursor of 16, 6-chloro-1-phenyluracil (8), but also other new chlorinated regioisomers of mono N-substituted pyrimidine (9) and uracil (14) were isolated and characterized by the reductive dechlorination of them.
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■ One-electron Transfer Reactions of Pyrylium Cations
Dan Farcasiu,* Alexandru T. Balaban, and Ursula L. Bologa
*Department of Chemical Engineering, University of Pittsburgh, 1249 Benedum Hall, Pittsburgh, PA 15261, U.S.A.
Abstract
One- and two-step one-electron transfers to pyrylium cations, generating pyranyl free radicals and anions, respectively, as well as one-electron transfers from pyrylium ions, forming dication radicals, and the properties of these species are critically reviewed.
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■ Further Development of the Ketoxime-based Pyrrole Synthesis
Boris A. Trofimov* and Al'bina I. Mikhaleva
*Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 1, Favorsky Street, Irkutsk, 664033, Russia
Abstract
Recent development and modification of the general synthesis of pyrroles and 1-vinylpyrroles by the reaction of ketoximes with acetylenes and their synthetic equivalents (vinyl halides and dihaloalkanes) in the presence of the strongly basic KOH/DMSO catalytic and eliminating pair (the Trofimov reaction) are briefly reviewed. The formation of 3H-pyrroles and other, isolable intermediates (O-vinyl ketoximes and hydroxypyrrolines) as well as side products are discussed.
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■ Heterocyclic Ketene Aminals
Zhi-Tang Huang* and Mei-Xiang Wan
*Institute of Chemistry, Academia Sinica, Beijing, China
Abstract
Heterocyclic ketene aminals are presented in view of their synthesis, reactions and applications in the preparation of fused heterocycles.