Regular Issue

Vol. 34, No. 8, 1992

20 data found. 1 - 20 listed
Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1483 - 1486
Published online:
DOI: 10.3987/COM-91-5932
Mechanistic Inversion of Photoinitiated Electron Transfer Processes in Aryl Imidazolidinones

Paul H. Mazzocchi,* Nai Yong Jing, and Kazuaki Oda

*Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, U.S.A.


Aryl imidazolidinones having o-carboxylic acid and ester containing aryl substituents were found to undergo different photochemical reactions. Although both reactions are suggested to proceed by electron transfer mechanisms, the donor and acceptor groups are interchanged.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1487 - 1490
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DOI: 10.3987/COM-92-6027
Tetra-2-thienyl- and Tetrakis(5,2’-bithiophene-2-yl)thiophenes and Selenophenes

Juzo Nakayama,* Kanji Sawada, Akihiko Ishii, and Masamatsu Hoshino

*Department of Chemistry, Faculty of Science, Saitama University, Urawa, Saitama 338, Japan


Heating a mixture of di-2-thienylacetylene (1) and elemental selenium in benzene at 220-225 °C for 9 h in a stainless steel autoclave affords tetra-2-thienylselenophene (2b) in 65% yield. In similar ways, heating a mixture of bis(5,2’-bithiophene-2-yl)acetylene (3) and elemental sulfur or selenium gives tetrakis-(5,2’-bithiophene-2-yl)thiophene (4a) or selenophene (4b), respectively, in satisfactory yields.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1491 - 1495
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DOI: 10.3987/COM-92-6045
New Cyclization Reactions of 3-Dialkylamino-4-aminopyridines under Conditions of Nitration

Yutaka Miura,* Sakae Takaku, Yoshiharu Nawata, and Masatomo Hamana

*Production Technology Research Laboratories, Chugai Pharmaceutical Co., Ltd., Ukima 5-1-5, Kita-ku, Tokyo 115, Japan


Treatment of 3-dialkylamiono-4-aminopyridines (1) with nitric and sulfuric acids affords imidazo[4,5-c]pyridine derivatives (2, 3 and 4) and 1,2,3-triazolo[4,5-c]pyridine 2-oxides (5) by cyclization reaction of the corresponding 4-nitroaminopyridines.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1497 - 1502
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DOI: 10.3987/COM-92-6049
New, Short Synthesis of (±)-Geissoschizine

Mauri Lounasmaa,* Reija Jokela, Jari Miettinen, and Minna Halonen

*Laboratory for Organic and Bioorganic Chemistry, Technical University of Helsinki, SF-02150 Espoo, Finland


A short, easy way to prepare indole alkaloid (±)-geissoschizine (1) is described.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1503 - 1506
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DOI: 10.3987/COM-92-6064
Reaction of Quadricyclane with Electron Deficient p-Benzoquinones

Ken-ichi Hirao,* Tohru Yokozawa, Asami Yamashita, and Tomoki Watanabe

*Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060, Japan


Quadicyclane reacted thermally in a [π2+σ2+σ2] manner with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and chloranil to give cyclobutanes and a spiro oxetane, respectively.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1507 - 1510
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DOI: 10.3987/COM-92-6091
Nucleophilic Fluorination of Chlorinated N-Heterocycles with Tetrabutylphosphonium Hydrogendifluoride and Dihydrogentrifluoride

Yukitaka Uchibori, Masayuki Umeno, and Hirosuke Yoshioka*

*RIKEN(Institute of Physical and Chemical Research), Wako, Saitama 351-01, Japan


Fluorination of various chlorinated N-heterocycles with tetrabutylphosphonium hydrogendifluoride (1) or dihydrogentrifluoride (2) readily proceeded in high yields under mild conditions.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1511 - 1514
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DOI: 10.3987/COM-92-6097
A Novel Nitrile Oxide Precursor; 2-Methyl-4-nitro-5(2H)-isoxazolone

Suguru Higashida, Hiroko Nakashima, Yasuo Tohda, Keita Tani, Nagatoshi Nishiwaki, and Masahiro Ariga*

*Department of Chemistry, Osaka Kyoiku University, Minamikawabori-cho, 4-88, Tennoji-ku, Osaka 543, Japan


2-Methyl-4-nitro-5(2H)-isoxazolone (1) was found to be a versatile precursor for a functionalized nitrile oxide by reaction with dipolarophiles giving 3-(N-methylcarbamoyl)isoxazole (2 or 3) derivatives.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1515 - 1518
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DOI: 10.3987/COM-92-6098
Enantioselective Synthesis of Indolizidine Alkaloid: A Formal Total Synthesis of (-)-Pumiliotoxin 251D

Toshio Honda,* Michiyasu Hoshi, and Masayoshi Tsubuki

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


An enantioselective formal total synthesis of (-)-pumiliotoxin 251D was achieved by employing the Sharpless kinetic resolution of the 2-furylmethanol derivative (3) and a stereoselective radical cyclisation of the thiocarbonylimidazolide (10) as key steps.

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Communication | Regular issue | Vol 34, No. 8, 1992, pp. 1519 - 1522
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DOI: 10.3987/COM-92-6107
First Example of Intramolecular 1,3-Dipolar Cycloaddition of Non-stabilized Azomethine Ylide Generated from Tertiary Amine N-Oxide

Seiichi Takano,* Yoshiaki Sugihara, and Kunio Ogasawara

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980, Japan


The reaction of two optically active 1-alkyl-3,4-diallyloxypyrrolidine 1-oxides, (9) and (15), under basic conditions has been examined. The 1-benzyl derivative (9), on reaction with lithium diisopropylamide, furnished a single pyrrolidine derivative (11) by intramolecular 1,3-dipolar cycloaddition of an N-benzylidene azomethine ylide (10), while the 1-methyl derivative (15) reacted with tert-butyllithium in the presence of trimethylaluminum to afford only a single 7-azabicyclo[2.2.1]heptane derivative (19) by spontaneous intramolecular 1,3-dipolar cycloaddition of the endocyclic azomethine ylide (17).

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1523 - 1538
Published online:
DOI: 10.3987/COM-92-5978
Synthesis of 2,2-Dimethylbenzoxazepinones by the Schmidt Reaction of 2,2-Dimethyl-4-chromanones

Albert Lévai,* Tibor Timár, László Frank, and Sándor Hosztafi

*Department of Organic Chemistry, Lajos Kossuth University, H-4010 Debrecen, Hungary


2,3-Dihydro-2,2-dimethyl-1,4-benzoxazepin-5(4H)-ones and 2,3-dihydro-2,2-dimethyl-1,5-benzoxazepin-4(5H)-ones have been synthesized by the Schmidt reaction of 2,2-dimethyl-4-chromanones. 2,2-Dimethylbenzoxazepinthiones have been prepared by the reaction of 2,2-dimethylbenzoxazepinones with Lawesson’s Reagent.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1539 - 1545
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DOI: 10.3987/COM-92-6018
Polyhalogenoaromatic Compounds. Part 51. Synthesis of New Heterocycles from Pentachloropyridine and 2,3,5,6-Tetrachloropyridine with Aliphatic Diamines

Luis Juliá,* Jordi Rius, and Hans Suschitzky

*Departamento de Materials Organics Halogenats, Centre d’Investigació i Desemvolupament, (CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain


The reaction of pentachloropyridine or 2,3,5,6-tetrachloropyridine with N,N,N’,N’-tetramethylethanediamine (TMEDA) or N,N’-dimethylethanediamine (DMEDA) in dimethylformamide gave dihydropyridopyrazines (5, 9) and (6) respectively by replacement of the 2,3- or 3,4-chlorine atoms.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1547 - 1554
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DOI: 10.3987/COM-92-6038
Structure Determination of Some Pyronylpyrazoles, Correction of the Structures Described as Pyrano[4,3-c]pyrazoles

Ana Brbot-Saranovic,* Branka Katusin-Razem, and Ivan Vickovic

*Department of Chemistry and Biochemistry, Veterinary Faculty, University of Zagreb, Croatia


Reaction of ethyl 2-hydroxy-4-(4-hydroxy-6-methyl-2-pyron-3-yl)-4-oxo-2-butenoate (1) with phenylhydrazine has been reported to give four products. The corrected structures (4 and 5) were subsequently established for two of them, which had been reported previously as 3,5-disubstituted N-phenylpyrazole-4-carboxylic acids (8, 9). Consequently, the structures of their cyclized products, instead of the reported pyrano[4,3-c]pyrazoles (10, 11) are pyronylpyrazoles (6, 7). The structure (6) was also confirmed by means of X-ray crystallography.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1555 - 1564
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DOI: 10.3987/COM-92-6050
Two New Benzofuran Derivatives, Corylifonol and Isocorylifonol from the Seeds of Psoralea corylifolia

Yun-Lian Lin and Yueh-Hsiung Kuo*

*Department of Chemistry, National Taiwan University, Taipei, Taiwan, R.O.C.


The seeds of Psolalea corylifolia were extracted with ether and 60% EtOH, successively. The latter extract was found to contain the known constituents psoralen, angelicin, corylifolinin, bukuchiol, p-hydroxybenzoic acid, and astragalin, together with two new benzofuran derivatives, corylifonol and isocorylifonol. Their structures have been elucidated by spectral evidence and chemical transformation.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1565 - 1572
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DOI: 10.3987/COM-92-6052
[3+2] Cycloaddition of Chiral Azomethine Ylides from Aminosugar N-Oxides. Enantioselective Synthesis of 3,4-Disubstituted Pyrrolidines

Jacqueline Chastanet, Hassana Fathallah, Guillermo Negron, and Georges Roussi*

*Institut de Chimie des Substances Naturelles, C.N.R.S., 91198 Gif-sur-Yvette, France


The base deprotonation method, applied to amino-sugar N-oxides prepared from methyl 2,3-anhydro-4,6-O-benzylidene-α-D-mannopyranoside (8) and methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside (9), allows the easy generation of complex and very reactive sugar azomethine ylides. Fair yields of the major diastereomeric pyrrolidines resulting from [3+2] cycloaddition to stilbene are thus obtained with good asymmetric induction. The easy climination of the chiral appendage as starting epoxides gives access to the enantiomerically enriched 3,4-diphenylpyrrolidines.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1573 - 1582
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DOI: 10.3987/COM-92-6062
Reaction of Ketene Dithioacetals with Thioamides. A Synthesis of Pyrimidine Derivatives

Antonio Lorente,* M. Luisa García, Misericordia Fernández, and José L. Soto

*Department of Organic Chemistry, University of Alcalá, 28871 Alcalá de Henares (Madrid), Spain


Reaction of ketene dithioacetals with thioamides gave 5-cyano-2-methyl(or phenyl)-6-methylthio-4-thioxopyrimidines.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1583 - 1604
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DOI: 10.3987/COM-92-6073
1,3-Cycloaddition of Benzonitrile Oxides to Diazepines. I. 1-Ethoxycarbonyl-5-methyl-1,2-diazepine

Paolo Beltrame,* Enzo Cadoni, Maria M. Carnasciali, Gioanna Gelli, Adolfo Lai, Angelo Mugnoli, and Marcella Pani

*Dipartimento di Chimica Fisica ed Elettrochimica, Università, Via Golgi 19, I-20133 Milano, Italy


Stable aryl nitrile oxides (1a-e) and 1-ethoxycarbonyl-5-methyl-1,2-diazepine (2) undergo 1,3-cycloaddition reactions to give isomeric 1,2,4-oxadiazole (3), 4,5-dihydroisoxazole (4) and isoxazole (5) derivatives, the first one being in any case the most abundant product. Overall kinetics were measured at temperatures in the range 50-90 °C, in 1,1,2,2-tetrachloroethane and mixtures of the latter with DMF; rate coefficients for the parallel reactions were, thus, obtained. Substituent and solvent effects are discussed.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1605 - 1612
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DOI: 10.3987/COM-92-6080
Reinvestigation of Nitrosation of Methylpyridines and Their 1-Oxides and Deoxygenation of 3-Pyridinecarbaldehyde 1-Oxide Oxime

Yoshinobu Tagawa, Kazuya Hama, and Yoshinobu Goto*

*Faculty of Pharmaceutical Sciences, Fukuoka University, Nanakuma, Jonan-ku, Fukuoka, 814-01, Japan


Treatment of methylpyridines and their 1-oxides with t-butyl nitrite in the presence of potassium t-butoxide in liquid ammonia afforded the corresponding aldoximes in good yields except for the case of 3-methylpyridine. The reaction of 3-methylpyridine with t-butyl nitrite in the presence of lithium 2,2,6,6-tetramethylpiperidide and N,N,N’,N’-tetramethylethylenediamine in tetrahydrofuran at -78 °C led to 3-(3-methyl-4-pyridyl)methylpyridine. Deoxygenation of 3-pyridinecarbaldehyde 1-oxide oxime was effected in 78% yield by the action of t-butyldimethylsilyl chloride-imidzole-sodium iodide-zinc followed by desilylation with tetrabutylammonium fluoride to give 3-pyridinecarbaldehyde oxime.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1613 - 1621
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DOI: 10.3987/COM-92-6087
Dimerization of Indolo[1,2-b][2,7]naphthyridine-5,12-quinone

Deborah A. Davis and Gordon W. Gribble*

*Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, U.S.A.


Attempts to isomerize indolo[1,2-b][2,7]naphthyridine-5,12-quinone (5) to ellipticine quinone (7) with various nucleophiles (cyanide, methoxide, halide, thiophenoxide) lead instead to 6,6’-bis(indolo[1,2-b][2,7]naphthyridine-5,12-quinone) (8), the dimer of 5.

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Paper | Regular issue | Vol 34, No. 8, 1992, pp. 1623 - 1630
Published online:
DOI: 10.3987/COM-92-6102
Synthesis of 5,8-Quinoxalinediones and 5,8-Quinazolinediones

Yoshiyasu Kitahara, Shinsuke Nakahara, Yoshihiro Tanaka, and Akinori Kubo*

*Meiji College of Pharmacy, 1-35-23 Nozawa, Setagaya-ku, Tokyo 154, Japan


5,8-Quinoxalinediones (3a-c, 12, 13), dibenzo[a,c]phenazine-10,13-diones (5a, b), 5,8-quinazolinediones (17, 23), and 4,5,8(3H)-quinazolinetrione (21) were prepared using oxidative demethylation of the corresponding 5,8-dimethoxy compounds with cerium (IV) ammonium nitrate.

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Review | Regular issue | Vol 34, No. 8, 1992, pp. 1631 - 1659
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DOI: 10.3987/REV-92-444
The Significance of the Bond Lengths and Bond Orders of Conjugated Unsaturated Organic Molecules. The Role of Hetero-Aromaticity in the Tertiary Structures of DNA

Vernon G. S. Box

*Department of Chemistry, City College of the City, University of New York, Convent Avenue @ 138th Street, New York, NY 10031, U.S.A.


New criteria (based on X-ray crystallographic data) for assessing the presence of delocalization in conjugated π systems reveal that delocalization is not a widespread phenomenon in the ground states of many of these π systems. Instead, these molecules prefer to retain highly localized, independent, π systems. Thus, many explanations of the structural features and reactivities of these unsaturated organic molecules, based on their presumed delocalized ground states, must be critically reviewed. This is especially important for understanding the chemistry and properties of hetero-aromatic molecules.

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20 data found. 1 - 20 listed