HETEROCYCLES
An International Journal for Reviews and Communications in Heterocyclic ChemistryWeb Edition ISSN: 1881-0942
Published online by The Japan Institute of Heterocyclic Chemistry
Regular Issue
Vol. 75, No. 1, 2008
Published online: 28th September, 2007
■ Heteropentalene Mesomeric Betaines of Type C: Progress since the Early 1980s
Dietrich Moderhack
*Institute of Pharmaceutical Chemistry, Technical University, D-38106 Brauschweig, Germany
Abstract
This account briefly summarizes the achievements made in the last twenty-five years. Synthesis, properties, and reactivity are dealt with here.
Published online: 2nd October, 2007
■ Electrooxidative Cyclization of Benzylideneaminothiophenols to the Corresponding 2-Arylbenzothiazoles
Mitsuhiro Okimoto,* Takashi Yoshida, Masayuki Hoshi, Kazuyuki Hattori, Masashi Komata, Kenta Tomozawa, and Tomohito Chiba
*Department of Applied and Environmental Chemistry, Kitami Institute of Technology, Koen-cho 165, Kitami, Hokkaido 090-8507, Japan
Abstract
Several benzylideneaminothiophenols were electrochemically oxidized in methanol containing sodium acetate as the supporting electrolyte, to afford the corresponding 2-arylbenzothiazols. The reaction proceeded via intramolecular cyclization involving the formation of a new bond between the benzylic carbon of the substrate and the sulfur of the thiol group. Based on the yields, room temperature and the use of two equivalents of sodium acetate relative to the substrate as the supporting electrolyte were found to be the optimal reaction conditions. The electrooxidation presumably involves a two-electron oxidation process.
Published online: 10th September, 2007
■ Synthesis of Cycloalkanoindoles, the Carba Analogs of Physostigmine
Imre Kiraly, Gabor Hornyanszky, Katalin Kupai, and Lajos Novak*
*Department of Organic Chemistry, Research Group for Alkaloid Chemistry of the Hungarian Academy of Sciences, Budapest University of Technology and Economics, Gellért tér 4, H-1521 Budapest, Hungary
Abstract
The title compounds 9 were prepared by combined aza-Claisen rearrangement/intramolecular ring-closure reaction of N-allylaniline derivatives 3, followed by BBr3 mediated cleavage of methoxy group and subsequent formation of the phenylcarbamyl derivatives.
Published online: 20th September, 2007
■ Synthesis of 2,4-Dibromopyridine and 4,4’-Dibromo-2,2’-bipyridine. Efficient Usage in Selective Bromine-Substitution under Palladium-Catalysis
Ramón García-Lago, José-Lorenzo Alonso-Gómez, Cristina Sicre, and María-Magdalena Cid*
*Organic Chemistry Department, Universtiy of Vigo, Lagoas-Marcosende, 36310 Vigo, Spain
Abstract
We report an efficient method for preparing 2,4-dibromopyridine and 4,4’-dibromo-2,2’-bipyridine from the corresponding nitroazine N-oxide in one step via a tandem nucleophilic substitution-N-oxide reduction process. The one step preparation of 4,4’-dihalo-2,2’-bipyridines from dihalopyridines via a Stille reaction is also described. 4,4’-Dibromo-2,2’-bipyridine undergoes selective mono- or disubstitution processes under palladium catalysis. This short synthetic procedure is an efficient and reliable process for preparing conjugated pyridine and 2,2’-bipyridine building blocks for applications in coordination chemistry and materials science.
Published online: 14th September, 2007
■ Synthesis of Vinca Alkaloids and Related Compounds. Part 109. An Intramolecular [4+2] Cycloaddition Mediated Biomimetic Synthesis of (±)-Iboxyphylline
Flórián Tóth, György Kalaus*, Gergely Pipa, István Greiner, Áron Szollosy, Attila Rill, Ágnes Gömöry, László Hazai, and Csaba Szántay
*Faculty of Chemical Engineering, Budapest University of Technology and Economics, 1111 Budapest, Szt. Gellért tér 4, Hungary
Abstract
The pentacyclic alkaloid 1 could be synthesized by an intramolecular [4+2] cycloaddition reaction of intermediate 11, which had been obtained from tryptamine derivative 4 and aldehyde 5. After full epimerization of 13 the cyclization reaction furnished a mixture of 14a and 14b. Separation of the stereoisomers 14a and 14b and subsequent reduction with LiAlH4 resulted in (±)-iboxyphylline (14a → 1) and its epimer, (±)-20-epiiboxyphylline (14b → 15).
Published online: 20th September, 2007
■ On the Tautomerism of Cinnolin-4-ol, Cinnolin-4-thiol, and Cinnolin-4-amine
Wolfgang Holzer,* Gernot A. Eller, and Simeon Schönberger
*Department of Drug Synthesis, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
Abstract
Detailed NMR spectroscopic investigations (1H, 13C, 15N) with cinnolin-4-ol (1) reveal this compound to exist exclusively in the cinnolin-4(1H)-one form in deuteriodimethyl sulfoxide solution. This finding is confirmed by comparison of the NMR spectroscopic data of 1 with those of the corresponding ‘ixed’ O-methyl and N-methyl derivatives, i.e. 4-methoxycinnoline (3) and 1-methylcinnolin-4(1H)-one (5). Similarly, cinnoline-4-thiol (4) is present in the thione form in deuteriodimethyl sulfoxide, whereas cinnolin-4-amine (7) exists in the amino form. In addition, in-depth analyses of the NMR spectra of some simple 4-substituted cinnolines are provided.
Published online: 20th September, 2007
■ An Efficient Three-Component, One-Pot Synthesis of New Pyrimido[4,5-d]pyrimidine-2,4-diones
Minoo Dabiri, Seyyedeh Cobra Azimi, Hamid Arvin-Nezhad, and Ayoob Bazgir*
*Chemistry Department, Faculty of Sciences, Shahid Beheshty University, P. O. Box 19395-4716 Tehran, Iran
Abstract
A new pyrimido[4,5-d]pyrimidine-2,4-(1H,3H,5H,8H)-dione derivatives have been synthesized in good yields in a three-component, one-pot, and efficient process by condensation reaction of 6-amino-1,3-dimethyluracil, aldehyde and 2-benzylisothiourea hydrochloride under solvent-free conditions.
Published online: 20th September, 2007
■ Convenient Synthesis of 1,4-Dihydro-2H-3,1-benzoxazin-2-ones by Iodocyclization of t-Butyl 2-Vinylphenylcarbamate
Kazuhiro Kobayashi,* Shuhei Fukamachi, Daizo Nakamura, Osamu Morikawa, and Hisatoshi Konishi
*Department of Materials Science, Faculty of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan
Abstract
It has been found that t-butyl 2-vinylphenylcarbamate derivatives underwent iodocyclization on treatment with iodine in the presence of sodium hydrogencarbonate to afford 4-iodomethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one derivatives in generally good yields. The reduction of these 4-iodomethyl derivatives with tributyltin hydride gave the corresponding 4-methyl derivatives in good yields.
Published online: 10th September, 2007
■ A Concise Approach to (±)-Tubifoline Based on the Palladium-Catalyzed Cross-Coupling Reaction of Indolylborate
Minoru Ishikura,* Norinobu Takahashi, Koji Yamada, and Takumi Abe
*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
Abstract
The palladium-catalyzed tandem cyclization-cross-coupling protocol using 1H-indol-2-yltrialkylborate (indolylborate) proved to be a versatile approach to the generation of 2-(4-piperidylmethyl)indole, which was successfully used for the preparation of (±)-tubifoline.
Published online: 28th September, 2007
■ 1H NMR Sulfinyl Group Substituent Effects of Dithiinodiazine S-Oxides as a Key for Structure Assignment of Parent Dithiinodiazines
Andrzej Maslankiewicz,* Maria J. Maslankiewicz, Andrzej Zieba, and Krzysztof Marciniec
*Department of Organic Chemistry, The Medical University of Silesia, Jagielloñska 4, 41-200 Sosnowiec, Poland
Abstract
1,4-Dithiinodipyridine 1 was prepared by reduction of 4-chloro-3-chlorosulfonylopyridine (8) with HI / H3PO3 system. Sulfur-assisted thermal isomerization of 1 resulted in a mixture of 1 and 2. Treatment of dithiinodiazines 1, 2, 5, and 6 with a nitrating mixture led almost selectively to respective S-monooxides 1a, 2a, 5a, and 6a. Due to the significant values of sulfinyl group substituent effects, 1H NMR spectra of 1,4-dithiino-S-oxides 1a, 2a, 5a, and 6a permitted for structure assignment of parent dithiins 1, 2, 5, and 6 and confirmed regioselectivity of the reaction of dithiins 1, 2, 5, and 6 with nitrating mixture.
Published online: 28th September, 2007
■ Megastigmane Glycosides from the Leaves of Salacia chinensis
Seikou Nakamura, Yi Zhang, Yutana Pongpiriyadacha, Tao Wang, Hisashi Matsuda, and Masayuki Yoshikawa*
*Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan
Abstract
Six new megastigmane glycosides, foliasalaciosides A1 (1), A2 (2), B1 (3), B2 (4), C (5), and D (6), were isolated from the methanolic extract of the leaves of Salacia chinensis (Hippocrateaceae) collected in Thailand together with 16 known constituents. The absolute stereostructures of 1-6 were elucidated on the basis of chemical and physicochemical evidence including the application of the modified Mosher’s method.
Published online: 12th October, 2007
■ Studies with Functionally Substituted Enamines: Synthesis of 2-Aroyl-3-dimethylamino-2-propenenitrile and Their Reactivity toward Nitrogen Nucleophiles
Fawzia Al-Qalaf, Mervat Mohammed Abdelkhalik,* Amal Al-Enezi, and Johara Rashed Al-Ajimi
*Applied Science Department, College of Technological Studies, Public Authority for Applied Education and Training, Shuwaikh 70654, Kuwait
Abstract
A facile and efficient synthesis of 2-substituted 3-dimethylamino-2-propenenitrile 4a-c is described. Reaction of 4a-c with hydrazine hydrate afforded 3-substituted-1H-4-pyrazole carbonitrile 9a-c. Compounds 4a-c reacted with 5-methyl-1H-pyrazol-3-amine to give 7-substituted pyrazolo[1,5-a]pyrimidine-6-carbonitrile 12a-c and 2-substituted 5-aminopyrazolo[1,5-a]pyrimidine 16a,b, and with 1H-benzo[d]imidazol-2-amine to give 3-substituted 2-aminobenzo[4,5]imidazo[1,2-a]pyrimidine 19a,b and 4-substituted benzo[4,5]imidazo[1,2-a]pyrimidine 3-carbonitrile 21c. The structures of compounds obtained were deduced based on 1HNMR, HMBC-15N and NOE difference experiments.
Published online: 10th September, 2007
■ Three Mexicanolides from the Root Bark of Entandrophragma angolense
Nsiama Tienabe Kipassa, Hiroaki Okamura, Matsumi Doe, Yoshiki Morimoto, Tetsuo Iwagawa, and Munehiro Nakatani*
*Department of Chemistry and Bioscience, Faculty of Science, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan
Abstract
Three new mexicanolide-type rings B,D-seco limonoids were isolated together with four known rings B,D-seco compounds, methyl angolensate, secomahoganin, 3β-hydroxy-3-deoxycarapin, and xyloccensin K from the root bark of a meliaceous plant Entandrophragma angolense. The structure of these new compounds was elucidated by spectrospcopic means. The antifeedant property of the isolated compounds is also briefly described.
Published online: 20th September, 2007
■ Sulfuric Acid Mediated Heterocyclization of ortho-Cyanomethylnitroarenes to Benzo[c]isoxazoles and Fused Benzo[c]isoxazoles
Mehdi Bakavoli,* Mehdi Pordel, Mohammad Rahimizadeh, Pooneh Jahandari, and Esmaeel Rezaei Seresht
*Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, 91775-1436, Iran
Abstract
The vicarious nucleophilic substitution of hydrogen (VNS) is used as the key step to convert substituted 5-nitrobenzimidazoles 1a-b into their ortho-cyanomethyl derivatives 2a-b. Conc. sulfuric acid mediated heterocyclization of these intermediates gave the novel 3H-imidazo[4’,5’:3,4]benzo[c]isoxazole-8-carboxamides 3a-b. To generalize this synthetic strategy for benzo[c]isoxazoles syntheses, the VNS products of para-substituted nitrobenzene 4a-d were successfully converted to the new benzo[c]isoxazoles derivatives 5a-d.
Published online: 10th September, 2007
■ A New Cyclo-thioglucoside from the Seeds of Raphanus sativus L.
Bao-Min Feng, Li-Xin Duan, Ling Tang, Yue-Hu Pei, and Yong-Qi Wang*
*College of Bioengineering, Dalian University, Dalian Economic and Development Zone, 116622, China
Abstract
A cyclo-thioglucoside named as raphanuside was isolated from the seeds of Raphanus sativus L. The structure of raphanuside was determined on the basis of extensive spectroscopic means including HR-FAB-MS, 1D and 2D NMR experiments.
Published online: 2nd October, 2007
■ Densispicnins A and B, Two Unusual Monoterpenes from Pedicularis densispica Franch.
Hong-biao Chu, Du-qiang Luo,* Ning-hua Tan, and Xuan Tian
*College of Life Science, Hebei University, China
Abstract
Two unusual monoterpenes, densispicnins A (1), B (2), together with the four known monoterpenes, mussaenoside (3), yuheinoside (4), mussaenin A (5), argyol (6), were isolated from the whole plant of Pedicularis densispica Franch. The structures of 1 and 2 were elucidated mainly based on spectral data including 1D-, 2D-NMR (HSQC, HMBC, ROESY) and MS experiments.
Published online: 28th September, 2007
■ A Convenient One-Pot Preparation of N-Substituted 4-Phenylpiperidines
Shigehiro Asano and Hitoshi Ban*
*Dainippon Sumitomo Pharmaceuticals Co., Ltd., Enoki 33-94, Suita, Osaka 564, Japan
Abstract
N-Substituted 4-phenylpiperidines were readily synthesized by one-pot cyclization of diols with amines via bis-triflate intermediates. The new synthesis under mild conditions gave various N-substituted 4-phenylpiperidines in moderate to good yields.