Special Issue

Alan R. Katritzky's Special Issues, Vol. 37, No. 2, 1994

66 data found. 31 - 60 listedFirst Previous Next Last
Paper | Special issue | Vol 37, No. 2, 1994, pp. 869 - 882
Published online:
DOI: 10.3987/COM-93-S76
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.

PDF (432KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 883 - 890
Published online:
DOI: 10.3987/COM-93-S80
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).

PDF (317KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 891 - 896
Published online:
DOI: 10.3987/COM-93-S81
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.

PDF (123KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 897 - 902
Published online:
DOI: 10.3987/COM-93-S82
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.

PDF (171KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 903 - 914
Published online:
DOI: 10.3987/COM-93-S83
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.

PDF (288KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 915 - 932
Published online:
DOI: 10.3987/COM-93-S84
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.

PDF (471KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 933 - 943
Published online:
DOI: 10.3987/COM-93-S87
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).

PDF (226KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 943 - 954
Published online:
DOI: 10.3987/COM-93-S91
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.

PDF (300KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 955 - 965
Published online:
DOI: 10.3987/COM-93-S95
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.

PDF (258KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 967 - 978
Published online:
DOI: 10.3987/COM-93-S97
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.

PDF (225KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 979 - 983
Published online:
DOI: 10.3987/COM-93-S100
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.

PDF (143KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 985 - 992
Published online:
DOI: 10.3987/COM-93-S102
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.

PDF (236KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 993 - 996
Published online:
DOI: 10.3987/COM-93-S104
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.

PDF (123KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 997 - 1018
Published online:
DOI: 10.3987/COM-93-S106
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.

PDF (696KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1019 - 1024
Published online:
DOI: 10.3987/COM-93-S107
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.

PDF (156KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1025 - 1031
Published online:
DOI: 10.3987/COM-93-S108
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.

PDF (168KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1033 - 1039
Published online:
DOI: 10.3987/COM-93-S109
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.

PDF (157KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1041 - 1051
Published online:
DOI: 10.3987/COM-93-S113
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.

PDF (323KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1053 - 1068
Published online:
DOI: 10.3987/COM-93-S114
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.

PDF (355KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1069 - 1074
Published online:
DOI: 10.3987/COM-93-S118
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.

PDF (138KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1075 - 1082
Published online:
DOI: 10.3987/COM-93-S119
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.

PDF (169KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1083 - 1091
Published online:
DOI: 10.3987/COM-93-S120
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.

PDF (234KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1093 - 1107
Published online:
DOI: 10.3987/COM-93-S121
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.

PDF (370KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1109 - 1120
Published online:
DOI: 10.3987/COM-93-S123
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.

PDF (346KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1121 - 1140
Published online:
DOI: 10.3987/COM-93-S125
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.

PDF (446KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1141 - 1146
Published online:
DOI: 10.3987/COM-93-S133
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.

PDF (133KB)
Paper | Special issue | Vol 37, No. 2, 1994, pp. 1147 - 1164
Published online:
DOI: 10.3987/COM-93-S146
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.

PDF (422KB)
Review | Special issue | Vol 37, No. 2, 1994, pp. 1165 - 1192
Published online:
DOI: 10.3987/REV-93-SR4
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.

PDF (624KB)
Review | Special issue | Vol 37, No. 2, 1994, pp. 1193 - 1232
Published online:
DOI: 10.3987/REV-93-SR6
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.

PDF (694KB)
Review | Special issue | Vol 37, No. 2, 1994, pp. 1233 - 1262
Published online:
DOI: 10.3987/REV-93-SR7
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.

PDF (536KB)
66 data found. 31 - 60 listedFirst Previous Next Last