HETEROCYCLES

■ Professor Sir Derek H. R. Barton and Heterocycles

Takayuki Shioiri*

*Faculty of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan

■ Palladium Catalysed Arylation of Chrom-3-en-4-ol Acetates via Their Tributyltin Enolates

Dervilla M. X. Donnelly,* Jean-Pierre Finet, and Paul H. Stenson

*Department of Chemistry, University College Dublin, Belfield, Dublin 4,. Ireland

Abstract

Arylation of in situ generated chrom-3-en-4-ol tributyltin enolates with aryl bromide in the presence of a catalytic amount of PdCl₂[(o-tolylphosphine)₃]₂ gives moderate to good yields of the corresponding isoflavanones.

■ A Novel Synthesis of (±)-Isochanoclavine-I

Toshiko Kiguchi, Naoko Kuninobu, Takeaki Naito, and Ichiya Ninomiya*

*Kobe Women’s College of Pharmacy, Motoyamakita, Higashinad, Kobe, Hyogo 658, Japan

Abstract

Total synthesis of (±)-isochanoclavine-I (9) was achieved via the route involving fragmentation reaction of the 3-aminoalcohol 4.

■ The Radical Relay Chlorination of Fleible Nicotinate Esters

Radhika Batrd and Ronald Breslow*

*Department of Chemistry, Columbia University, 3000 Broadway, Mail Code 3114, New York, New York 10027, U.S.A.

Abstract

Dodecyl and hexadecyl nicotinates undergo radical relay chlorination with selectivities consistent with molecular models and with results in steroids. Alternating effects are seen, reflecting straight-chain conformations. A novel sequence for product analysis is validated, and used to compare the nicotinate template, and its N-oxide, with previously studied iodoaryl templates.

■ Intramolecular [2+2] Cycloadditions of Keteniminium Salts Derived from α- and β-Amino Acids. A Route to Azabicyclic Ketones

Benoit Gobeaux and Léon Ghosez*

*Laboratoire de Chimie Organique de Synthèse, Université Catholique de Louvain, Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium

Abstract

Unsaturated N-tosylaminoketeniminium salts generated in situ from α- and β-aminoamides readily underwent intramolecular [2+2] cycloadditions t o give azabicyclic ketones in good yields.

■ Propellanes. XCII. The Stereochemistry of Diels-Alder Reactions of Tetraenic Propellanes and of 1,6-Bridged[10]annulenes with 4-Substituted 1,2,4-Triazoline-3,5-diones

Ilana Agmon, Menachem Kaftory, Pnina Ashkenazi,* Raffaello Muller, Wolfgang von Philipsborn, and David Ginsburg

*Department of Chemistry, Israel Institute of Technology, Haifa 32000, Israel

Abstract

Syn-anti, endo-exo types of configuration in the title compounds, in general, and in 11-cyano-1,6-methanol[10]annulene, as a specific case, are discussed.

■ A Convenient Access to 3,4-Disubstituted Isoquinolines from Benzocyclobutenyl Ketoximes

Kozo Shishido, Kou Hiroya, Keiichiro Fukumoto,* and Tetsuji Kametani

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan

Abstract

The thermolyses of several benzocyclobutenyl ketoximes (2) proceed via a preferential electrocyclic reaction of Z-o-quinodimethane species (3) to yield - 3,4-disubstituted isoquinolines (5).

■ A Synthetic Approach to (±)-Vindoline

Kozo Shishido, Hironori Komatsu, Keiichiro Fukumoto,* and Tetsuiji Kametani

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan

Abstract

A synthesis of the potential intermediate of (±) vindoline was achieved from the isochromanone (6), which was obtained by thermolysis of the benzocyclobutene (5).

■ Free Radical Cyclization in the Synthesis of Fused Bicyclic β-Lactams

Viyyoor M. Girijavallabhan* and Ashit K. Ganguly

*Schering Research, 60 Orange Street, Bloomfield, New Jersey 07003, U.S.A.

Abstract

Free radical cyclization is applied to cephalosporin synthesis. Fragmentation and deoxygenation reactions are observed.

■ A Synthesis of a New-type Heterocyclic Compound by Using Diels-Alder Reaction of 2-Methylene-1,2-dihydropyridine Derivative

Hiroshi Tomizawa,* Hiroto Nakano, and Hiroshi Hongo

*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

The Diels-Alder reaction of 2-dicyanomethylene-l,2-dihydropyridines having an active methylene group at the 1-position (Ia-d) with N-phenylmaleimide gave isoquinuclidine derivatives (IIa-d) which were treated with triethylamine to afford new-type heterocyclic ring system, 2-azatricyclo[5.2.2.0^2,6]undecane derivatives (IIIa-d).

■ Synthesis of Benzofuans, Tetrahydrobenzopyrans, and Related Cyclic Ethers via Cyclic Carbopalladation

Ei-ichi Negishi,* Thinh Nguyen, Brian O’Connor, Jeffrey M. Evans, and Augustine Silveira, Jr.

*Wetherill Laboratory, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, U.S.A.

Abstract

Treatment of a variety of alkenyl ethers (1-8) derived from o- iodophenol, o-iodobenzyl alcohol, and (Z)-3-iodoallyl alcohols with a catalytic amount of Pd(PPh₃)₄ or Cl₂P (PPh₃)₂ in the presence of NEt₃ in refluxlng CH₃CN gives the corresponding cyclic ethers in good yields.

■ Stereocontrolled Synthesis of the Withanolide D Side Chain from 20-Oxosteroid

Tetsuji Kametani, Masayoshi Tsubuki, and Toshio Honda*

*Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan

Abstract

A new procedure for the construction of the withanolide D side chain starting from 20-oxopregnane is described. The key reactions are stereochemical control of C-20 and C-22 positions involving stereoselective hydrogenation of the enone 4, and an efficient transformation of the resulting γ-lactone 5 into the δ-lactone 8. Successful isomerization of the olefin 12 using RhCl₃ is also reported.

■ Enantioselective Synthesis of Naturally Occurring (—)-Tylophorine by Way of an Asymmetric Intramolecular Double Michael Reaction

Masataka Ihara, Yoshinobu Takino, Keiichiro Fukumoto,* and Tetsuji Kametani

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan

Abstract

Treatment of the 8-phenylmenthyl α. β -unsaturated amide ester (3) with tert.-butyldimethylsilyl trifluoromethanesulfonate and triethylamine produced, with a complete diastereofacial selection, the indolizidines (4), which were converted into (-)-(R)-tylophorine (1).

■ Carbonyl Radical Cyclizations: Preparation of Some Heterocyclic Ketones

David Crich,* K. Angeline Eustace, and Timothy J. Ritchie

*Department of Chemistry, University College , 20 Gordon Street, London, WC1H 0AJ, U.K.

Abstract

It has been possible to synthesize 3-methylchromanone, 3-methylthiochromanone and 2,3-dihydro-3-methylquinolin-4-one from salicylic acid, thiosalicylic acid and anthranilic acid respectively by carbonyl radical cyclizations.

■ Studies towards the Synthesis of Fredericamycin A

Marc Julia, Christian Roland, Emmanuel Vincent, and Jin Zhu Xu

*associé au CNRS, Département de Chimieassocié au CNRS, Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France

Abstract

An isocoumarin tricyclic ester related to rings ABC of the title compound has been synthesized. he possibility of exchanging the heterocyclic oxygen atom for nitrogen and of using an ester group for the construction of the side chain has been checked on a model compound.

■ Des-AB-steroids by a New Method of Cholesterol Degradation

Jacek W. Morzycki* and Jolanta Mudz

*Bialystock Branch, Institute of Chemistry, University of Warsaw, Al. Pilsudskiego 11/4, 15-443 Bialystok, Poland

Abstract

A two-step procedure for Westphalen diol diacetate 1 fragmentation to keto-aldehyde 5 and (4S)-4-hydroxy-2-methylcyclohexanones (6a and 6b) has been developed. Ozonolysis of a double bond in 1 followed by retroaldolization afforded compound 5 in 42 % yield.

■ Baytopine, a New Homoaporphine Alkaloid

Ales Husek, Nurhayat Sütlüpinar, Petr Sedmera, and Vilím Simánek*

*Institute of Medical Chemistry, Palacky University, 3, Hnevotínská, 775 15 Olomouc, Czech Republic

Abstract

Baytopine (2), a new alkaloid, was isolated from leaves and flowers of Merendera kurdica Bornm. and its structure was determined by spectroscopic means.

■ The Structure of New Oligosaccharide Antibiotics, 13-384 Components 1 and 5

A. K. Ganguly,* B. Pramanik. T. M. Chan, O. Sarre, Y. -T. Liu, J. Morton, and V. Girijavallabhan

*Schering Research, 60 Orange Street, Bloomfield, New Jersey 07003, U.S.A.

Abstract

Structures of 13-384 antibiotics have been deduced based on chemical degradation and spectroscopic evidence.

■ Concerted versus Stepwise Processes in Eliminative Fission of Oxacycles

Gwerydd Griffiths and Charles J. M. Stirling*

*Department of Chemistry, University College of North Wales, Bangor LL57 2UW, U.K.

Abstract

2-Phenyleulphonylmethyloxetan (2a) has been synthesised and the kinetics of base promoted eliminative ring fission have been determined. The results show, by comparison with the behaviour of related substrates studied previously, that (i) the 3-ring:4-ring differential for concerted proceeees is much smaller than for stepwise processes, particularly those in which the extent of ring fission is large and (ii) the effect of-gem-dimethyl substitution (thorpe-Ingold effect) is to restrain ring fission but only to a small extent when compared with stepwise presses.

■ Preparation and Diels-Alder Cycloadditions of Substituted Vinylene Carbonates (1,3-Dioxol-2-ones) and Related Compounds

Michael E. Jung,* Roberto B. Blum, Bruce J. Gaede, and Matthias R. Gisler

*Department of Chemistry and Biochemistry, University of California, 405 Hilgard Avenue, Los Angels, CA 90024, U.S.A.

Abstract

Several substituted vinylene carbonates have been prepared by efficient routes and the dienophilicity of these and related compounds in Diels-Alder cycloaddition has been evaluated.

■ Formation of Phenyl Substituted Heteroaromatics by Ligand Coupling in the Reaction between Heteroaryl Sulfoxides with Phenyl Grignard Reagent

Shigeru Oae,* Takashi Takeda, and Shoji Wakabayashi*

*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

In the reaction of heteroaryl alkyl sulfoxides with phenylmagnesium bromide, phenyl group was found to couple predominantly with 2-quinolyl group and 2-pyrimidinyl group.

■ Two New Alkaloids from an Indian Species of Zoanthus

Ch. Bheemasankara Rao,* D. Venkata Rao, Vegesna S. N. Raju, Brian W. Sullivan, and D. John Faulkner*

*Scripps Institution of Oceanography (A-012F), University of California, San Diego, La Jolla, CA 92093-0682a, U.S.A.

Abstract

A new species of Zoanrhur from the Bay of Bengal contains a novel group of alkaloids that possess antiinflammatory and analgesic properties. The structures of two new isomeric alkaloids, 28-deoxyzoanthenamine (4) and 22-epi-28-deoxyzoanthenmine (5), were elucidated by interpretation of spectral data.

■ New Alkaloids from Delphinium andersonii Gray

S. William Pelletier,* Palaniappan Kulanthaivel, and John D. Olsen

*Department of Chemistry, Institute for Natural Products Research, , Chemistry Building, Athens, Georgia 30602-2556, U.S.A.

Abstract

Investigation of Delphinium andersonii Gray afforded, in addition to ten known diterpenoid alkaloids, two new alklaoids, andersonidine (10) and 14-acetylnudicaulidine (11). Structure were deduced on the basis of spectroscopic evidence.

■ Isoteucrin H₄, a 19-Nor-neoclerodane Diterpenoid of Biogenetic Interest from Teucrium kotschyanum

Fatima Simões, Benjamin Rodriguez, Franco Piozzi,* Giuseppe Savona, Maurizio Bruno, and Nelly Apostolides Arnold

*Dipartimento di Chimica Organica, Università digli Studi di Palermo, Via Archirafi 20 90123 Palermo, Italy

Abstract

From the aerial parts of Teucrium kotschyanum a new neoclerodane diterpenoid, isoteucrin H₄ was isolated and its structure of (12S)-15,16-epoxy-2α-hydroxy-19-nor-neocleroda-5(10),13(16),14-triene-18,6β; 20,12-diolide (2) was established by spectroscopic means and by partial synthesis from teucrin H₄ (1). Isoteucrin H₄ is the first 19-nor-neoclerod-5(10)-ene derivative found in nature and has biogenetic importance, since structures with a C-5,C-10 double bond were postulated as intermediates in the biosynthesis of the diterpenoids belonging to the H-10α-19-nor-neoclerodane series.

■ Photoaddition of 2-Pyridones to Conjugated Dienes

Eisuke Sato, Yoshiya Ikeda, and Yuichi Kanaoka*

*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan

Abstract

Irradiation of 2-pyridones with conjugated cyclic dienes gave [4+4]cycloaddition products. Irradiation with conjugated non-cyclic dienes afforded 2-substituted derivatives, probably derived from oxetane intermediate, together with the [2+2]cycloaddition products.

■ Functionalization of Nitrogen and Oxugen Containing Heterocycles by Mercury Photosensitized Dehydrodimerizations

Richard R. Ferguson, Constantine G. Boojamra, Stephen H. Brown, and Robert H. Crabtree*

*Sterling Chemistry Laboratory, Yale University, 225 Prospect St., New Haven, CT 06511, U.S.A.

Abstract

Nitrogen and oxygen containing heterocycles can be functionalized by mercury photosensitzation.

■ Termal Cycloaddition Reactions of 4,5-Epoxy-4-azahomoadamantanes with Acetylenic 1,3-Dipolarophiles. Novel Formation of 4-Aza-homoadamantano[4,5-a]pyrrole Derivatives

Shoji Eguchi,* Koji Asai, and Tadashgi Sasaki

*Faculty of Engineering, Nagoya University, Chikusa, Nagoya, Aichi 464-8601, Japan

Abstract

Thermal cycloaddition reactions of 5-alkyl-4,5-epoxy-4-azahomoadamantanes 1b-d with dimethyl acetylenedicarboxylate (DMAD) and methyl propiolate afforded 4-azahomoadamantano[4,5-a]pyrrole derivatives 5a-c and 7, while the reaction of the 5-unsubstituted epoxy-4-azahomoadamantane 1a with DMAD gave the oxazoline derivative 4 in a low yield.

■ N-Hydroxypyridine-2-thione Carbamates as Aminiun Radical Cation Precursors. Transannular Radical Cyclizations Forming Tropanes

Martin Newcomb* and Donald J. Marquardt

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

Abstract

N-Methoxyclohept-4-enaminium cation radical, produced from the corresponding responding N-hydroxypyridine-2-thione carbamate, cyclizes to give, ultimately, tropane and substituted tropanes in high yield.

■ New Method and Reagents in Organic Synthesis. 81. Lithium Trimethylsilyldiazomethane: A Useful Reagent for the Preparation of 1,2,3-Triazoles from Ketenimines

Toyohiko Aoyama, Sachiko Katsuta, and Takayuki Shioiri*

*Faculty of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan

Abstract

Lithium trimethylsilyidiazomethane smoothly reacts with ketenimines to give 1,2,3-triazoles in good yields.

■ Chiral Economy with Respect to Rotational Isomerism: Rational Synthesis of Hamatine and (Optionally) Ancistrocladine from Joint Helical Precursors

Gerhard Bringmann* and Johannes R. Jansen

*Institut für Organische Chemie, Universität Wurzburg, Am Hubland, D-97074 Wurzburg, Germany

Abstract

Unlike the target alkaloids 1a and 1b, which are configurationally stable at the biaryl linkage, the helicene-like distorted cyclic precursors 2 and 7 show dramatically lowered rotational thresholds: they equilibrate at room temperature, already. In contrast to the lactones 2a/b, however, the cyclic ethers 7a and 7b interconvert slowly enough to be separated conveniently, on a preparative scale. Ring opening of the desired helimer (e.g. 7b) and re-equilibration/re-separation of the rest allows the transformation of practically the whole synthetic material, optionally into 1b or 1a - practising “axially chiral economy”.