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
Derek H. R. Barton's Special Issues, Vol. 28, No. 2, 1989
Published online:
■ An Efficient Stereoselective Synthesis of Z-2-(2-Methylene Cyclohexylidene)ethanol by the Photosensitized Oxygenation of 1-Vinylcyclohexene. A Model for Ring A of Calcitriol
Jacqueline Ficini,* Claude Barbara, and Ouathek Ouerfelli
*Laboratoire de Chimie Organique de Synthèse, UA 408, Université P. et M. Curie, 8, rue Cuvier 75005 Paris, France
Abstract
The reaction of singlet oxygen with the vinylcyclohexene leads to an endoperoxide which is a model for a possible route to ring A of calcitriol.
Published online:
■ Isolation and Structure of the Cell Growth Inhibitory Depsipeptides Dolastatins 11 and 12
George R. Pettit,* Yoshiaki Kamano, Haruhisa Kizu, Claude Dufresne, Cherry L. Herald, Roger J. Bontems, Jean M. Schmidt, Fred E. Boettner, and Ronald A. Nieman
*Center Research Institute, Department of Chemisty, Arizona State University, Main Campus, P.O. Box 872404, Tempe, AZ 85287-2404, U.S.A.
Abstract
Two antineoplastic cyclic depsipeptides designated dolastatin 11 (1) and dolastatin 12 (2) were isolated from the Indian Ocean sea hare Dolabello auricularia. Dolastatins 11 and 12 inhibited growth of the PS leukemia wilh ED50 2.7 x 10-3 and 7.5 x 10-2 μg/mL respectively. Detailed structural studies employing 400 MHz 1H,1H-COSY, 1H,13C-COSY, NOE, and HMBC experiments (in addition to acid and base hydrolysis, followed by GC-MS analysis) led to structure 1 for dolastatin 11 and to structure 2 for dolastatin 12.
Published online:
■ The Thermal and Photolytic Decomposition of 9-Aryl-9-xanthenyl Azides to 11-Arydibenzo[b,f][1,4]oxazepines
Philip Coombes, André Goosen,* and Benjamin Taljaard
*Department of Chemistry, University of Port Elizabeth, Port Elizabeth 6001, South Africa
Abstract
In contrast to the different ratios of products obtained in the thermal decomposition of some 9-aryl-9-xanthenyl azides, it was found that photolysis afforded the same product ratio. The mechanism of these reactions is discussed in terms of intermediates as well as conformational and electronic effects in the transition states.
Published online:
■ A General Approach to the Total Synthesis of Yuehchukene and Its Analogues. A Novel Anti-Implantation Agent
James Peter Kutney,* Francisco Javier Lopez, Shyl-Pyng Huand, and Hiroshi Kurobe
*Department of Chemisry, University of British Columbia, Vancouver 8, V5T 1W5, Canada
Abstract
A versatile synthetic strategy has been developed for the synthesis of the interesting dimeric indole natural product yuehchukene (17) and its epimer. 6a-epi-yuehchukene (22). Due to the anti-implantation activity associated with 17, it is important to develop a synthetic route not only to 17, but to a family of yuehchukene analogues with better chemical stability and/or elevated biological activity. The strategy described here and which utilizes the readily available and inexpensive isophorone (1) satisfies these requirements.
Published online:
■ Synthesis of Monocyclic Analogues of a Potent Thromboxane Receptor Antagonist, (±)-(5Z)-7-[3-endo-[(Phenylsulfonyl)amino]bicyclo[2.2.1]hept-2-exo-yl]heptenoic Acid (S-145)
Kenji Kawada and Tadahiko Tsushima*
*Shionogi Research Laboratories, Shionogi & Co. Ltd., Fukushima-ku, Osaka 553-0002, Japan
Abstract
Several monocyclic analogues of the potent thromboxane-A2 receptor antagonist S-145, i.e. cyclohexane, cyclopentane, tetrahydrofuran, and pyrrolidine, as well as the biclo[2.2.2]octane one were synthesized using allylation via oxime dianion and the Barton’s method for oxime reduction in the key steps.
Published online:
■ Homolytic Cyclization of O-Alkenyl-Se-phenylselenocarbonates. Synthesis of Lactones
Mario D. Bachi* and Eric Bosch
*Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
Abstract
0-Alk-3-enyl- and 0-alk-4-enyl-Se-phenyleslenocarbonates undergo regiospecific exo cyclization to the corresponding γ- and δ-lactones an treatment with tri-n-butylstannane and AIBN.
Published online:
■ Homolytic Cyclization of Selenol Esters. Synthesis of Charomanones
Mario D. Bachi* and Daniella Denenmark
*Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
Abstract
Acyl radicals produced by tributyltin hydride-azobisisobutyronitrile induced homolysis of phenylselenol esters undergo highly selective 6-exo-tring addition to double bonds, affording, in a chain reacticn, cyclic oxo-compounds in very high yield. Suitably substituted phenylselenosalicylates are thus converted into the corresponding chormanones.
Published online:
■ Preparation of All the Four Diastereomers of β-Phenylcysteine Methyl Ester through Chromatographic Optical Resolution of the 2,2-Dimethylthiazolidine Derivatives
Ukon Nagai* and Vincenzo Pavone
*Institute of Life Science, Mitsubishi Kasei, Minaiooya-11, machida-shi, Tokyo 194
Abstract
cis And trans-2,2-dimethyl-4-carbomethoxy-5-phenylthiazolidines prepared from the corresponding erythro- and threo-β-phenylcysteines were resolved into the enantiomers by use of a chiral HPLC column, from which all of the four chiral β-phenylcysteine methyl esters were obtained.
Published online:
■ Reactions of N-Acylimidazole with Nucleosides and Nucleotides
Yu Wang* and Yao-Quan Chen
*Academia Sinica, Shanghai Institute of Organic Chemistry, 345 Ling Ling Lu, 200032 Shanghai, China
Abstract
By controlling the pH of the reaction system and the addition of a base of an appropriate basicity, the selective acylation of ribonucleosides and ribonucleotides can be achieved by using N-acylimidazole. Ribonucleoside 2’,3’-cyclophosphates can be easily prepared by the reaction of N-acylmidazole with the corresponding 3’-nucleotides. The mechanisms and kinetics of the reactions of N-acylimidazoles with nucleosides and nucleotides were studied by means of 31P and 1H nmr.
Published online:
■ Controlled Annulation Reactions of 3-Methyl-4-oxo-1-thiacyclopent-2-ene-1,1-dioxide: A Useful Isoprenoidal Synthon
Catherine S. V. Houge-Frydrych, William B. Motherwell,* and Dennis M. O’Shea
*Department of Chemistry, Imperial College of Science, Technology and Medicine, GB-London SW7 2AY, U.K.
Abstract
The cyclic sulphone-enone (1) functions as a useful dienophile and dipolarophile in cycloaddition reactions to give adducts whose regicchemisny is controlled by the enone moiety. The radicophilic character of the electron deficient carbon-carbon double bond may also be used to achieve cyclopentannulation.
Published online:
■ A Short and Efficient Synthesis of (±)-Isoretronecanol and (±)-Trachelanthamidine
Nieves Cabezas, Josiane Thierry,* and Pierre Potier
*Institut des Chimie des Substances Naturelles, C.N.R.S., 1 avenue de la Terrasse, Bat. 27, 91198 Gif-sur-Yvette Cedex, France
Abstract
Radical decarboxylation of N-protected proline in the presence of dimethyl fumarate gave a thiopyridyl adduct 5 which was readily transformed into isoretronecanol 1 and trachelanthamidine 2.
Published online:
■ Reactions of Hexachlorocyclotriphosphazene with 1,2-Diaminopropane
Vadapalli Chandrasekhar* and Narreddi Sivasankara Reddy
*Department of Chemistry, Indian Institute of Technology, Kanpur 208016, India
Abstract
The reactions of hexachlorocyclotriphosphazene with 1,2-diaminopropane are discussed.
Published online:
■ A Remarkable Catalytic Effect of the Potassium Salt of 1-Hydroxybenzotriazole on Peptide Bond Formation
Kusuo Horiki* and Atsuko Murakami
*Shionogi Research Laboratories, Shionogi & Co. Ltd., Fukushima-ku, Osaka 553-0002, Japan
Abstract
A semiquantitative investigation was done on the catalytic effects of 1-hydroxybenzotriazole (HOBt) (5) and the potassium salt 6 of HOBt (5) on peptide bond formation by the active ester method. HOBt (5) was found to catalyze the aminolysis reaction of two different types of active esters, benzyloxycarbonyl-L-phenylalanine 2,4,5-trichlorophenyl ester (1) and benzyloxycarbonyl-L-phenylalanine 1-succinimidyl ester (2), in tetrahydrofuran (THF) and in a dipolar aprotic dimethylformamide (DMF) solvent. A large rate enhancement was also observed in the aminolysis reaction of 1 in THF when the potassium salt 6 of HOBt (5) was added in the presence of dicyclohexyl-18-crown-6 (7). The rate acceleration in the aminolysis reaction of the active esters by 5 and 6 may reasonably be explained in terms of nucleophilic catalysis.
Published online:
■ Electrophilic Amination. Direct Primary Amination of Arenes Using Phthalimide Derivatives
Rudolph A. Abramovitch,* Joseph M. Beckert, Pennamuthiriar Chinnasamy, He Xiaohua, William Pennington, and A. R. Vinutha Sanjivamurthy
*Department of Chemistry, Clemson University, Clemson, SC 29631, U.S.A.
Abstract
Electrophilic primary amination of arenes has been achieved by the thermolysis or photolysis of N-sulfonyloxyphthalimide in the presence of trifluoromethanesulfonic acid or of 1-phthalimido-2,4,6-triphenylpyridinium tetrafluoroborate in the presence of CF3CO2H. The diacylnitrenium 10 was probably formed in the latter case. The structure of one of the byproducts, 7 was established by single crystal X-ray analysis.
Published online:
■ Rearrangements of 1-Piperidinocyclopropyl Ketimines. A Synthesis of 2-Substituted Pyrroles
Harry H. Wasserman,* Robert P. Dion, and James M. Fukuyama
*Department of Chemistry, Yale University, P.O. Box 6666, New Haven, Connecticut 06511, U.S.A.
Abstract
On heating 1-(N-piperidino)cyclopropyl ketimines with HBF4, rearrangement to 2-substituted pyrroles takes place.
Published online:
■ 4,9-Methano-1H-aza[11]annulene: A 12π-Homologue of Pyrrole
Walter Lange, Wilhelm Haas, Hans Schmickler, and Emanuel Vogel*
*Institut für Organische Chemie, Universität zu Köln, Greinstraße 4, D-50939 Köln 41, Germany
Abstract
4,9-Methano-1H-aza[11]annulene (3), to be regarded as a 12π-homologue of pyrrole, was synthesized from 1,6-methano[10]annulene by a reaction sequence patterned after that employed in the conversion of benzene to 1H-azepine (1). In contrast to 1, which is atropic, 3 - a bridged structural variant of the elusive 1H-aza[11]annulene - qualifies as paratropic, although its peripheral elevenmembered ring possesses a non-planar conformation.
Published online:
■ Mechanism of Action of a Biomimetic Phenytoin Receptor
Saul Wolfe,* Kiyull Yang, Raymond John Bowers, Hee-Sook Shin, and Chang-Kook Sohn
*Department of Chemistry, Queen‘s University, Kingston, Ontario K6L 3N6, Canada
Abstract
The anticonvulsant drug phenytoin (5,5-diphenylhydantoin) is a specific inhibitor of sodium ion transport by the redox-switched cyclodepsipeptide ionophore Boc-L -cystinyl-glycy-L-prolyl-glycyl-L-prolyl-L-cystine-OCHPh2 (phencepytin), a biomimetic model of a sodium channel receptor. Using various N-methylated analogs of phenytoin and phenceptin, the inhibition is found to involve N1 of the drug and the gly4-nitrogen of phenceptin, as predicted by a calculated structure of the 1:1 phenytoin-phenceptin complex.
Published online:
■ Synthesis of Regiospecifically Substituted Pyrimidyl Derivatives and Their Incorporation into Penems
Hans-Georg Capraro,* Marc Lang, and Peter Schneider
*Pharmaceuticals Division, Research Department, Ciba-Geigy Limited, CH-4002 Basel, Switzerland
Abstract
Syntheses of regiospecifically substituted pyrimidines are described. Depending on the reaction conditions, N1- or N3-substituted pyrimidines are obtained. It has been shown that substitution on uracil under Mitsunobu conditions yields N1-substituted products. Incorporation of these derivatives into the penem nucleus gives penem antibiotics with extremely long half-lives.
Published online:
■ A Novel Synthesis of Benzimidazolinones
Paulo S. Almeida, Ana M. Lobo,* and Sundaresan Prabhakar
*Chemistry Department, Faculty of Chemical Technology, New University of Lisbon, Quinta da Torre, 2825 Monte da Caparica, Portugal
Abstract
A new route to N-monosubstituted benzimidazolinones, involving an hetero-oxy Cope rearrangement, consists in the reaction of hydroxamic acids with cyanogen bromide.
Published online:
■ Displacement with Nitrogen Nucleophiles at C-3’ of 7-Aminocephalosporanic Acid and Derivatives Promoted by Trialkylsilyl Trifluoromethanesulphonates
David G. Acton, Kevin J. Rogers, and J. Philip Poyser*
*Chemistry I Department, ICI Pharmaceuticals, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, U.K.
Abstract
Replacement of a 3’-acetate group of a cephem by an alkylamino group can be mediated by trialkylsilyl trifluoromethanesulphonates in dichloromethane or acetonitrile inter alia. Comparable yields to the more usual 3’-iodo routes have been achieved, using a quick and simple procedure.
Published online:
■ Stereoselective Synthesis of 3-Hydroxy-2,6-dialkylpiperidines
Kenn E. Harding* and Michael W. Jones
*Department of Chemistry, Texas A & M University, College Station, Texas 77843-3255, U.S.A.
Abstract
A new method for stereoselective synthesis of 3-hydroxy-2,6-diakylpiperidine alkaloids is reported. The key trans-oxazolidine intermediate 8 was generated by mercuric ion-initiated cyclofunctionalization of an N-acylaminomethyl ether derivative of allylic alcohol 5 (6 --> 7). Racemic deoxocassine (3) was synthesized by addition of a C11 chain (8 --> 9), cleavage of the oxazolidtne ring under basic conditions (9 --> 17), and reductive amination to generate the piperidine ring (17 --> 3). It was found that attempts to cleave the cyclohexyl carbamate group of oxazolidine 9 under acidic conditions resulted in rapid rearrangement to oxazolidinone 10 with inversion of stereochemistry at the O-substituted carbon. This oxazolidinone was converted to racemic isodeoxycassine (4) by ring cleavage (10 --> 14) and reductive amination. Treatment of oxazolidine 9 under strongly acidic conditions led to isolation of the 3-acetoxy-2,5-dialkylpiperidine 11, the product of an intramolecular Mannlch reaction.
Published online:
■ Studies of Australian Soft Corals. XLV. Epoxidation Reaction of Cembranoid Diterpenes: Stereochemical Outcomes
Bruce F. Bowden and John C. Coll
*Department of Chemistry and Biochemistry, James Cook University of North Queensland, Townsville, Queensland 4811, Australia
Abstract
Epoxidation of the cembranoid diterpene (1) afforded the known 7S,8S-epoxide (2), the 7R,8R-epoxide (3), the 11R,12R-epoxide (4) and the 11S,12S-epoxide (5) in the ratio 1:3:3:10. Similar epoxidation of the cembranolide (1R,2R,3E,7E,11E)-cembra-3,7,11,15-tetren-17,2-olide (6) afforded the 7S, 8S-epoxide (7), the 7R,8R-epoxide (8), the 11R,12R-epoxide (9) and the 11S,12S-epoxide (10) in the ratio of 1:5:6:8. Only one of the products (8), from the second epoxidation reaction was known. The other three compounds are reported for the first time. This study reveals a significant preference for epoxidation at the 11,12-double bond. No evidence of epoxidation at the 3,4-double bond was detected in either system.
Published online:
■ 1,2,4-Trioxanes as Masked, Dual Purpose, Functional Groups
Charles W. Jefford, Jean-Claude Rossier, and John Boukouvalas
*Department of Organic Chemistry, Laboratory fo Crystallography, University of Geneva, 30, quai Ernest Ansermet, 1211 Geneva 4, Switzerland
Abstract
1,2,4-Trioxanes readily undergo reductive cleavage upon treatment with zinc and acetic acid to furnish the corresponding 1,2-dials and C3-derived carbonyl compounds in high yield.
Published online:
■ Cation Radicals of Heterocyclic N-Oxides and Their Reactions
Yurii V. Geletii, Vladimir V. Strelets, Vladimir Ya. Shafirovich, and Alexander E. Shilov*
*Institute of Chemical Physics, 142432 Chernogolvska, Russia
Abstract
Cation radicals of heterocyclic N-oxides were generated by electro and photochemical one-electron oxidation of corresponding N-oxides. In their interaction with cyclohexane and toluene an intermediate complex was found to be produced which reacted with dioxygen to form oxidation products. One of the ways of cation radicals transformation is their deoxygenatian producing corresponding amines. A hypothesis was put forward that cation radicals could be intermediates in hydrocarbon oxidation in pyridine solution.
Published online:
■ Stereochemistry in Borohydride Reduction of 7-iminocephems: An Improved Method for Conversation of the 7α-Amino-1-oxa(thia)cephems into the 7β-Amino Isomers
Tsutomu Aoki and Wataru Nagata*
*Shionogi Research Laboratories, Shionogi & Co. Ltd., Fukushima-ku, Osaka 553-0002, Japan
Abstract
Sodium cyanoborohydride in methanol containing hydrogen chloride (pH~3) proved to be an excellent reagent system for smooth and highly stereoselective reduction of the 7-imino-1-oxa(thia)cephems 6 or their equivalent 7-methoxy amines 8 to the corresponding 7β-amines 2. Borane-pyridine (H5C5N.BH3)or borane-trimethylamine complex [(CH3)3N.BH3] is also useful, although less efficient. The imines 6 or the methoxy amines 8 were formed simply by hydrogen chloride catalyzed methanolysis of the methylsulfenylimino derivatives 9. The experimental conditions were common to the above reduction process and, thus, both the methanolysis and the reduction could be performed in one pot. Combination of this one-pot procedure for the conversion of the sulfenylimines 9 into the 7β-amines 2 with the procedure for the preparation of 9 from the 7α-amines 1 provided an improved general method for the preparation of biologically important 7β-amino-1-oxa(thia)cephems from the corresponding 7α-amines 1.
Published online:
■ Iridoids from Endemic Chilean bignoniaceae
Juan A. Garbarino and Marcello Nicoletti*
*Dipartimento di Biologia Vegetale, Università degli Studi di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185 Roma, Italy
Abstract
Several iridolds were isolated from 4 species of endemic Chilean Bignoniaceae.
Published online:
■ A Cerium Metal-Mediated Coumarin Synthesis
Kazuo Nagasawa and Keiichi Ito
*Hokkaido College of Pharmacy, 7-1 Katsuraoka-cho, Otaru 047-02, Japan
Abstract
Chemoselective carbonyl 1.2-addition of organocerium reagent derived from polysubstituted phenyllithium and cerium(III) chloride to t-butyl acetoacetate and the succeeding acid-treatment furnish the substituted 4-methylcoumarins in reasonable yields.
Published online:
■ Stereoselective Addition of Lithiated Heterocycles to Chiral α-Amino Aldehydes
M. T. Reetz,* W. Reif, and X. Holdgrün
*Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany
Abstract
Lithiated heterocycles 5-9 add diastereoselectively to optically active α-N,N-dibenzylamino aldehydes 1 with 80-95% nonchelation control.
Published online:
■ Heterocycles from Diacetyl Phenols: Synthesis of Benzodioyrans, Acetylchromenes and Pyrano[1,2]benzisoxazoles
Asoke Banerji* and Govind P. Kalena
*Chemical Ecology Section, Bio-organic Division, Bhabha Atomic Research Centre, Trombay, Bombay 400 085, India
Abstract
Novel and facile syntheses of benzodipyrans, acetylchramenes and pyranol[1,2]benzisoxazoles from 2,4- and 4,6-diacetylresorcinols have been described. Regioselective condensations and reductions have been used as the key steps.
Published online:
■ Formation of Heterocyclic Hazardous Compounds by Thermal Degradation of Organic Compounds
Dieter Bieniek, Müfit Bahadir, and Friedhelm Korte
*Gesellshaft für Strahlen- und Umweltforschung mbh München, Institut für Ökologische, Ingolstädter Landstr. 1, D-8042 Neuherberg, Germany
Abstract
2,3,7,8-Tetrabromodibenzofuran in ppm concentrations can be generated via reductive debromination and subsequent intramolecular cyclization during thermolysis of polybrominated aromatic compounds such as decabromodiphenyl ethers which are used as flame retardants in plastics. The respective tetrabromodibenzodioxin isomer is produced in moderate amounts. In analogy to the chlorinated isomers the formation of toxic substances from incineration or fire accident constitutes a potential hazard.