Special Issue

Derek H. R. Barton's Special Issues, Vol. 28, No. 2, 1989

78 data found. 61 - 78 listedFirst Previous
Paper | Special issue | Vol 28, No. 2, 1989, pp. 1007 - 1013
Published online:
DOI: 10.3987/COM-88-S120
5-Aza-10-tellura-5,10-dihydroanthracenes (Phenotellurazines)

Thomas Junk and Kurt J. Irgolic

*Department of Chemistry, Texas A & M University, College Station, Texas 77843-3255, U.S.A.

Abstract

5-Aza-10-tellura-5,10-dihydroanthracene (phenotellurazine) was prepared in seven percent yield by mercurating diphenylamine with mercury(II) acetate, converting the 4-acetatomercudiphenylamine to the chloro derivative, and reacting it with tellurium tetrachloride. The 4-(phenylamino)phenyltellurium trichloride was not isolated but refluxed in glacial acetic acid for twelve hours to cause isomerization to 2-(phenylamino)phenyltellurium trichloride and cyclization to phenotellurazine 10,10-dichloride, which was reduced with aqueous sodium sulfide to phenotellurazine. Benzo[a]phenotellurazine was similarly obtained in 53 percent yield starting with 2-(phenylamino)naphthalene. The phenotellurazines were characterized by elemental analyses, 1H-, 13C- and 125Te- nmr spectroscopy, and mass spectrometry.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1015 - 1035
Published online:
DOI: 10.3987/COM-88-S121
Synthesis of 6-Aryl-4-hydroxypiperidin-2-ones and a Possible Applications to the Synthesis of a Novel HMG-CoA Reductase Inhibitor

Michael J. Ashton, Susan J. Hills, Chriastpher G. Newton, John B. Taylor, and Sylvie C. D. Tondu

*Degenham Research Centre, Rhone-poulenc Ltd., Degenham, Essex, RM10 7XS, U.K.

Abstract

A series of 6-aryl-4-hydroxypiperidin-2-ones (11a-11g) were synthesised with the key step being a Dieckmann cyclisation of the appropriate methyl 3-(ethoxycarbonylacetylamino)-3-(substituted) propionate (8a-8g) and this new synthetic route was successfully applied to the synthesis of 4-hydroxy-6-(2-phenylethyl)piperidin-2-one(11h). The application of this strategy to the synthesis of the putative HMG-CoA reductase inhibitor 6-[2-(2-benzyloxy-4,6-dichlorophenyl)ethyl]-4-hydroxypiperidin-2-one (11i) was attempted. but failed during the Dieckmann cyclisation of methyl 3-(ethoxycarbonylacetylamino)-3-[2-(2-benzyloxy-4,6-dichlorophenyl)-ethyl]propionat (8i). An alternative synthesis of a 1:1 diastereomeric mixture of (11i) was achieved by the reductive cleavage of the isoxazoline (24) with Raney nickel. The mixture of diastereoisomers (11i) was inactive in-vitro and in vivo (rat) against HMG-CoA reductase

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1037 - 1050
Published online:
DOI: 10.3987/COM-88-S122
Formation of 2,2-Spiro-substituted 2,3-Dihydrobenzofurans

George A. Morrison, Peter G. Sammes, and James P. Simmonds*

*School of Chemistry, The University, Hull HU6 7RX, U.K.

Abstract

Routes from substituted resorcinols to spiro-substituted dihydrobenzofurans are described. Whilst use of acid-catalysd condensation between a resorcinol and an aldehyde only gave low yields of dihydrobenzofurans and lacked regiocontrol, use of a nucleophilic aromatic substitution approach was successful.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1051 - 1060
Published online:
DOI: 10.3987/COM-88-S126
Observations on the Preparation of 2β-Hydroxy-19-oxoandrost-4-ene-3,7-dione; Synthesis of a 2β,19-Oxaandrost-4-ene-3,7-dione

Vincent C. O. Njar, Gerhard Spiteller, Jerzy Wicha, and Eliahu Caspi*

*The Worcester Foundation for Experomental Biology, Shrewbury, MA 01545, U.S.A.

Abstract

Several modifications of the synthesis of the title compounds were explored and are reported.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1061 - 1076
Published online:
DOI: 10.3987/COM-88-S127
Synthesis of 3-(Alkyl and Aryl)thio-2-isocephems

Jozsef Aszodi,* Jean-François Chantot, Jeannine Collard, and Georges Teutsch

*Centre de Recherche ROUSSEL-UCLAF, 102-111, route de Noisy, 93230 Romainville, France

Abstract

Synthesis of 3-S-substituted isocephems has been carried out in a convergent way using readily available intermediates such as 4-mercaptomethylazetidinone 3 and chloropyruvates 4 prepared by the reaction of sulfenyl chlorides with t-butyl diazopyruvate. During the synthesis, mild acid catalyzed decarboxylation of the β-carboxy ketene-dithioacetal moiety was observed as a side-reaction.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1077 - 1084
Published online:
DOI: 10.3987/COM-88-S128
Aminoalkylation of Aldehydes with Glyoxal N,N-Dimethlmonohydrazone Yields Stable 4-Substituted Pyrrolin-3-ones

Abdallah Zinoune, Jean-Jacques Bourguignon, and Camille-Georges Wermuth

*Laboratoire de Pharmacochimie Moleculaire, (UPR 421 DU CNRS), Centre de Neurochimie du CNRS, 5, rue Blaise Pascal, 67084 Strasbourg-Cedex, France

Abstract

Aminoalkylation reaction of various enolizable aldehydes with glyoxal N,N-dimethylmonohydrazone led to 4-substituted 1-N,N-dimethyl-3-morpholinopyrroles 3, which are easily hydrolyzed to novel pyrrolin-3-ones 5.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1085 - 1099
Published online:
DOI: 10.3987/COM-88-S130
Synthesis of Triazolo- and Tetrazoloquinoline Derivatives with Antithrombotic Activity

Patrice Desos, Gilbert Schlewer,* and Camille Georges Wermuth

*Laboratoire de Pharmacochimie Moleculaire, (UPR 421 DU CNRS), Centre de Neurochimie du CNRS, 5, rue Blaise Pascal, 67084 Strasbourg-Cedex, France

Abstract

The syntheses of eight triazolo- or tetrazoloquinolines derived from Y-590, an antithrombotic agent, are reported with the objective to investigate the bioisosteric replacement of the quinoline lactam function of Y-590 by a triazolic or tetrazolic ring system. The synthetic strategy employed involved either the formation of the triazolo-or tetrazoloquinoline followed by the introduction of the pyridazione side-chain for the preparation of monotriazolo- or monotetrazoloquinolines, or the synthesis of a pyridazinoylquinoline followed by the simultaneous creation of bis triazolic or tetrazolic fused rings.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1101 - 1113
Published online:
DOI: 10.3987/COM-88-S132
Synthesis and Pharmacoclogical Activity of a Pyrido[3’,4’:5,4]pyrrolo[1,2-c][1,4]benzodiazepine-3,10-dione, a New Benzodiazepine-β-carboline Type Hybrid Molecule

Robert H. Dodd,* Xavier Doisy, Pierre Potier, Marie-Claude Potier, and Jean Rossier

*Institut des Chimie des Substances Naturelles, C.N.R.S., 1 avenue de la Terrasse, Bat. 27, 91198 Gif-sur-Yvette Cedex, France

Abstract

Diethyl 2,3-dihydro-6-azaindoline-2,5-dicarboxylate 4b was synthesized and used as starting material in the preparation of a novel benzodiazepine-β-carboline type hybrid molecule (3aR,S)-ethyl 3,10-dioxo-2,3,3a,4-tetrahydro-10H-pyrido[3’,4’:5,4]pyrrolo[1,2-c][1,4]benzodiazepine-6-carboxylate 5b. The benzodiazepine receptor binding affinities of this compound and its precursors were found to be very modest in vitro. These results confirm our previously proposed model of the configuration of the benzodiazepine and β-carboline binding sites on the receptor as represented by the configuration of these two moieties in the high affinity hybrid 3.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1115 - 1120
Published online:
DOI: 10.3987/COM-88-S134
Design and Reactivity of Organic Functional Groups — 2-Pyridylsulfonates as Nucleofugal Esters: Remarkably Mild Transformations into HAlides and Olefins

Stephen Hanessian, Masahiro Kagotani, and Kossi Komaglou

*Department of Chemistry, University of Montreal, Montréal, Que’bec H3C 3J7, Canada

Abstract

The novel 2-pyridylsulfonate esters are excellent leaving groups for the preparation of bromides and olefins under very mild reaction conditions. Displecements occur with inversion of configuration.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1121 - 1134
Published online:
DOI: 10.3987/COM-88-S123
The Chemistry of N-Substituted Benzotriazoles. Part 18. A Study of the Influence of Structure on the 1- to 2-(N,N-Dialkylaminoalkyl)benzotriazole Equilibrium

Alan R. Katritzky* and Konstantina Yannakopoulou

*Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, P. O. Box 117200, Gainesville, FL 32611-7200, U.S.A.

Abstract

The equilibrium constants, the associated free energies for the equilibria, and the free energies of activation for the isomerization process of a series of 1- and 2-N,N-dialkylaminoalkyl)benzotriazoles of types (8)-(11) were calculated from the variable temperature 1H-nmr spectra. Trends in the magnitudes of these energies and equilibrium constants are correlated with the molecular structure.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1135 - 1156
Published online:
DOI: 10.3987/COM-88-S138
Aromatic Energies of Some Heteroaromatic Molecules

Michael J. S. Dewar* and Andrew J. Holder

*Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712-1074, U.S.A.

Abstract

Heats of formation derived from the AM1 semiempirical method were used to determine the aromatic energies (AE) of the following systems: pyridine, pyridazine, pyrimidine, pyrazine, 1,2,4,5-tetraazine, phosphabenzene, 1,2-, 1,3-, 1,4-diphosphabenzene, hexaazine, hexaphosphabenzene, silabenzene, thiophene, pyrrole and furan. Two methods were employed for AE estimates. One usad the heats of union of atomic pairs (with elimination of H2) of appropriate nonaromatic precursors. The other method used a comparison of the heats of hydrogenation of aromatic species to estimate the AE.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1157 - 1167
Published online:
DOI: 10.3987/COM-88-S141
Conversion of Olefins into Five-membered Nitrogen Heterocycles by Radical Cyclization

Derrick L. J. Clive* and Ali Y. Mohammed

*Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada

Abstract

2-(Phenylseleno)alkyl cyanamides, available in one step from olefins, according to a known procedure, are easily alkylated on nitrogen by allylic and propargylic halides. The products undergo radical cyclization in the presence of a stannane to produce five-membered nitrogen heterocycles by an exo trigonal or exo digonal pathway. The method can be used to make spiro heterocycles and bicyclic compounds with cis ring-fusion geometry.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1169 - 1178
Published online:
DOI: 10.3987/COM-88-S146
A Facile Route to "Open Chain" Analogues of DDATHF

Edward C. Taylor,* Philio M. Harrington, and Chuan Shih

*Department of Chemistry, Princeton University, Princeton, New Jersey 08544, U.S.A.

Abstract

N-(4-[4-(2,4-Diamino-6(1H)-oxopyrimidin-5-yl)butyl]benzoyl)-L-glutamic acid (7-DM-DDATHF, 18) is a representative of a new series of achiral analogues of the potent anticancer agent 5,10-dideaza-5,6,7,8-tetrahydrofolic acid (DDATHF). Members of this “open chain” pyrimidine series, 18,19, and 20, were synthesized via guanidine cyclization of 6, 7, and 8 to give the pyrimidines 9, 10, and 11. Ester hydrolysis, glutamate coupling and final saponification yielded the target compounds.

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Paper | Special issue | Vol 28, No. 2, 1989, pp. 1179 - 1192
Published online:
DOI: 10.3987/COM-88-S147
Highly Functionalized Aziridines II; A Facile Synthesis of Diethyl Aziridinylphosphonates and 2-Chloroaziridinylphosphonates

Philippe Coutrot,* Abdelaziz Elgadi, and Claude Grison

*Laboratoire de Chimie Organique II (U.A. CNRS 486), Campus Victor Grignard, Université de Nancy I, 54506 Vandoeuvre Les Nancy Cédex, France

Abstract

The reaction of diethyl 1-lithio-1-chloromethylphosphonate with aromatic mines gave aziridinylphosphonates in good yields and with an high stereoselectlvity. The resulting aziridines reacted with n-BuLi and led to the 2-Iithiated anions which were trapped with carbon tetrachloride to give 2-chloroaziridinylphosphonates in excellent yields.

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Review | Special issue | Vol 28, No. 2, 1989, pp. 1193 - 1203
Published online:
DOI: 10.3987/REV-88-SR7
Applications of Nmr Molecular Biology in Studies of the Enzyme Mechanisms of Vitamine B12 Biosynthesis

A. Ian Scott*

*Center for Biological NMR, Department of Chemistry, Texas A & M University, College Station, Texas 77843-3255, U.S.A.

Abstract

The active site of porphobilinogen (PBG) deaminase has been enriched with carbon-13 using cells of genetically engineered E. coli. Nmr spectroscopy has uncovered the structure of a novel dipyrromethane cofactor, covalently bound through Cys-242, which acts as a nucleophilic site for the covalent binding of substrate. Based on the results of pulse experiments with 13C-enriched S-adenosylmethionine (SAM), the sequence of methylation in the overall conversion of uro’gen III to cobyrinic acid is C2 > C7 > C20 > C17 > C12α > C1 > C5 > C15. These results are incorporated into a mechanistic scheme for corrin biosynthesis which also takes into account the discovery of a new series of corphinoids based on the type-I porphyrin template.

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Review | Special issue | Vol 28, No. 2, 1989, pp. 1203 - 1228
Published online:
DOI: 10.3987/REV-88-SR6
Original Syntheses of Epoxides Involving Organoselenium Intermediates

A. Krief,* W. Dumont, D. Van Ende, S. Halazy, D. Labar, J. -L. Laboureur, and Lé T. Q.

*Department of Chemistry, Facultés Universitaires Notre-Dame de la Paix, 61 rue de Bruxelles, B-5000 Namur, Belgium

Abstract

β-oxidoalkylselenonium salts and β-oxidoalkylselenones are valuable precursors of a large variety of epoxides. These species were synthesized by reaction of α-selenonio or α-selenonylalkylpotassium with carbonyl compounds or by reaction of a suitable base on β-hydroxyalkylselenonium salts or β-hydroxyalkylselenones. themselves obtained from β-hydroxyselenides. The most powerful method, based on the cyclization of β-hydroxyalkylselenonium salts is fully documented.

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Review | Special issue | Vol 28, No. 2, 1989, pp. 1229 - 1247
Published online:
DOI: 10.3987/REV-88-SR5
Asymmetric Induction in the Intramolecular Conjugate Addition of γ- or δ-Carbamoyloxy-α,β-unsaturated Esters. A New Method for Diastereoselective Amination and Divergent Syntheses of 3-Amino-2,3,6-Trideoxyhexoses

Masahiro Hirama and Shô Itô*

*Department of Chemistry, Graduate School of Science, Tohoku University, Aobayama, Sendai 980-8578, Japan

Abstract

Prominent 1,2- and 1,3-asymmetric induction in the intramolecular conjugate addition of γ- or δ-carbamoyloxy-α, β-unsaturated esters provides a new method for diastereoselective amination of acyclic olefinic systems, which has been applied to stereocontrolled divergent syntheses of 3-amino-2,3,6-trideoxyhexoses. Factors controlling the stereochemistry are discussed, and related cyclizations are also described.

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Review | Special issue | Vol 28, No. 2, 1989, pp. 1249 - 1256
Published online:
DOI: 10.3987/COM-88-S80
Glycosyl Thio-, Seleno-, and Tellurophosphates

Maria Michalska and Jan Michalski

*Laboratory of Orgab\nic Chemistry, Institute of Chemistry, Medical Academy, 90-151 Lódz, Muszynskiego 1, Poland

Abstract

A review of the chemistry of glycosyl thio-, seleno- and tellurophosphates is given with emphasis on their glycosyl-donor properties.

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78 data found. 61 - 78 listedFirst Previous