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
Ryoji Noyori's Special Issues, Vol. 76, No. 1, 2008
Published online: 22nd February, 2008
■ Synthesis of Chiral Tetrahydroisoquinoline-Derived β-Amino Alcohols and Their Application to Asymmetric Reaction
Yoshiyuki Hari, Masaki Sakuma, Ayako Miyakawa, Keiichiro Hatano, and Toyohiko Aoyama*
*Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanbe-dori, Mizuho, Nagoya 467-8603, Japan
Abstract
Three chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized by using the Ru-catalyzed asymmetric transfer hydrogenation of 6-methoxy-1-(2-methoxyphenyl)-3,4-dihydroisoquinoline as the key reaction. The ability of the synthesized β-amino alcohols as chiral ligands was evaluated in the addition of diethylzinc to benzaldehyde.
Published online: 15th February, 2008
■ Macropyllanosides A - D, Secoiridoid Glycosides from Hydrangea macrophylla subsp. serrata
Masao Kikuchi,* Rie Kakuda, and Yasunori Yaoita
*Department of Molecular Structural Analysis, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi 981-8558, Japan
Abstract
Four new secoiridoid glycosides, named macrophyllanosides A - D, were isolated from the leaves of Hydrangea macrophylla subsp. serrata. Their structures have been determined by spectroscopic and chemical means.
Published online: 14th March, 2008
■ Study of Synthetic Routes for the Spiroketal Fragment in Calyculin A Based on Conformational Analysis
Takatoshi Matsumoto,* Mototsugu Kabeya, Eiichi Morishita, and Takayuki Shioiri
*Institute of Multidsciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba, Sendai 980-8577, Japan
Abstract
The conformational analysis of the spiroketal fragment of calyculin A revealed that a series of the Wittig reaction by way of the Swern oxidation was suitable for the addition of the C1-unit for the preparation of the spiroketal fragment. It also clarified that failure in the reaction of cyanide and the tetraol equivalents was attributed to the steric and electrostatic effects of the symmetrical structures.
Published online: 11th March, 2008
■ Stereoselective Preparation and Cope Rearrangement of 2-CF3-cis-2,3-bis(alkenyl)oxiranes: A Facile Route to 2-CF3-Substituted Oxacycles
Masaki Shimizu,* Takuya Fujimoto, Xinyu Liu, Youhei Takeda, and Tamejiro Hiyama*
*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
Abstract
We describe here a facile route to 2-trifluoromethyl-substituted 4,5-dihydrooxepins, which involves stereoselective preparation and Cope rearrangement of 2-trifluoromethyl-cis-2,3-bis(alkenyl)oxiranes. Treatment of 1,1-dichloro-2-hydroxy-2-trifluoromethylalk-3-enes with alkenyllithium and then lithium 2,2,6,6-tetramethylpiperidide generated cis-2,3-bis(alkenyl)-2-lithio-3- trifluoromethyloxiranes, which reacted with a variety of electrophiles to give the corresponding tri- and tetrasubstituted oxiranes stereoselectively. Cope rearrangement of the cis-oxiranes proceeded upon heating, giving rise to 2-trifluoromethyl-substituted 4,5-dihydrooxepins in high to excellent yields. The Cope rearrangement is found remarkably accelerated by the presence of such metal substituents as boryl, silyl, and stannyl groups at 7-position, that can act as versatile functionalities for further elaboration of the ring-enlarged products. Subsequent reduction and oxidation of the rearranged products gave 2-trifluoromethylated oxepanes and oxepins in good yields.
Published online: 18th March, 2008
■ The Octaethylporphyrin-Dihexylbithiophene Derivatives Combined with Pyridine and Pyrimidine Rings. Their Syntheses and Proton-Mediated and Heat-Driven Spectral Changes
Hiroyuki Higuchi,* Naoto Hayashi, Takuya Matsukihira, Takanori Kawakami, Toru Takizawa, Junji Saito, Keiko Miyabayashi, and Mikio Miyake
*Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
Abstract
The octaethylporphyrin (OEP)-dihexylbithiophene (DHBTh) derivatives combined with pyridine (Pyr) and pyrimidine (Pym) as proton-acceptable rings (PAR) were synthesized, describable as OEP-DHBTh-PAR, in which all the OEP, DHBTh, and PAR components are connected with diacetylene linkage. Their 1H NMR and electronic spectral properties and electrochemical behaviors were studied under the neutral and acidic conditions. Reversible proton-mediated and heat-driven spectral changes of OEP- DHBTh-PAR were performed, reflecting both properties of PAR and DHBTh.
Published online: 21st April, 2008
■ Chiral Cationic Pd-Phosphinooxazolidine Catalysts for a Highly Efficient Asymmetric Diels-Alder Reaction in Ionic Liquids
Hiroto Nakano,* Yasuhiro Nishiuchi, Kouichi Takahashi, Reiko Fujita, Koji Uwai, and Mitsuhiro Takeshita*
*Tohoku Pharmaceutical University, 4-4-1, Komatsushima, Aoba-ku, Sendai 981-8558, Japan
Abstract
Chiral cationic palladium-phosphinooxazolidine catalysts in ionic liquid afforded good to excellent enantioselectivity in Diels-Alder reactions. The catalyst was recycled three times in ionic liquid (85-90%, 71-88% ee) or seven times in a mixed ionic liquid/CH2Cl2 (91-94%, 91-94% ee).
Published online: 25th March, 2008
■ Preparation of New Nitrogen-Bridged Heterocycles. 63. Unexpected Formation of Thieno[3’,4’:4,5]imidazo[1,2-a]pyridines
Akikazu Kakehi,* Hiroyuki Suga, Atsushi Izumita, and Takashi Abe
*Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Wakasato, Nagano 380-8553, Japan
Abstract
The alkaline treatment and dehydrogenation of pyridinium salts, obtainable from the S-alkylation of 3,5-dimethylpyridinium 2-alkylthio-1-cyano-2-thioxoethylides with some phenacyl bromides, afforded unexpected heterocycles, 3-alkylthio-1-arylcarbonyl-6,8-dimethylthieno[3’,4’:4,5]imidazo[1,2-a]pyridines, together with the corresponding 2-alkylthio-1-arylcarbonylthio- 6,8-dimethylindolizine-3-carbonitriles.
Published online: 4th April, 2008
■ Synthesis of 1,2,4-Trisubstituted Imidazoles and 1,3,5-Trisubstituted 1,2,4-Triazoles
Corinne Baumgartner, Lukas Brändli, and François Diederich*
*Laboratorium für Organische Chemie, ETH Zürich, Hönggerberg, HCI, CH-8093 Zürich, Switzerland
Abstract
We report synthetic strategies to easily access 1,2,4-trisubstituted imidazoles by introduction of different residues at C(2) and C(4) followed by substitution at N(1). Furthermore, a synthesis of trisubstituted 1,2,4-triazoles via a cyclization of hydrazonamides is described.
Published online: 8th April, 2008
■ Ruthenium Tetroxide Oxidation of N-Acyl Cyclic Amine-2-phosphonic Acid Diesters
Mamoru Kaname, Hironori Mashige, Shigeyuki Yoshifuji, and Haruki Sashida*
*Faculty of Pharmaceutical Sciences, Hokuriku University, Kanagawa-machi, Kanazawa 920-1181, Japan
Abstract
The utility of the ruthenium tetroxide (RuO4) oxidation of N-acyl cyclic amine-2-phosphonic acid esters was investigated. The oxidation of the N-protected cyclic amines (4, 5) having a phosphono diester group under the standard double layer condition of ethyl acetate-water using a catalytic amount of RuO2 and excess NaIO4 produce the corresponding lactams in good yields. The obtained lactam phosphono diesters (6, 7) were readily converted into the ω-amino-ω-phosphonocarboxylic acids (10, 11).
Published online: 17th April, 2008
■ A Facil and Efficient Synthesis of Mono- and Bis-functionalized meso-Substituted Porphyrins via Palladium-Catalyzed Negishi Cross-Coupling
Toshikatsu Takanami,* Miku Yotsukura, Wakaba Inoue, Naoyuki Inoue, Fumio Hino, and Kohji Suda*
*Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose, Tokyo 204-8588, Japan
Abstract
A series of mono- and bis-functionalized meso-substituted porphyrins bearing chemically reactive functional groups such as -COOR, -Cl, and -CN in the alkyl substituents at the meso positions were efficiently synthesized by the reactions of meso-brominated precursors with alkylzinc reagents via palladium-catalyzed Negishi cross-coupling.
Published online: 8th April, 2008
■ Synthetic Studies on Mycobacterium tuberculosis Specific Fluorescent Park’s Nucleotide Probe
Kai Li and Michio Kurosu*
*Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 1682 Campus Delivery, Fort Collins, CO 80523-1682, USA.
Abstract
An efficient synthesis of N-glycolyl Park’s nucleotide, a Mycobacterium tuberculosis (Mtb) specific peptidoglycan precursor, analog-fluorescein conjugate, is achieved. A fluorescent conjugated Mtb Park’s nucleotide analog 5 would be a very useful probe for the characterization of Mtb MraY, catalyzing the biosynthesis of lipid I from UDP-N-acyl-Mur-pentapeptide, and for the development of high-throughput screening (HTS) for Mtb MraY inhibitors.
Published online: 17th April, 2008
■ Silver-Catalyzed Synthesis of 1,2-Dihydroisoquinolines through Direct Addition of Carbon Pronucleophiles to ortho-Alkynylaryl Aldimines
Naoki Asao,* Salprima Yudha S., Tsutomu Nogami, and Yoshinori Yamamoto
*Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
Abstract
AgOTf-catalyzed reaction of ortho-alkynyl-arylaldimines with various kinds of pronucleophiles afforded a variety of 1,2-dihydroisoquinoline derivatives in good to high yields. Treatment of ortho-alkynyl-arylaldimines with a stoichiometric amount of AgOTf, followed by the protonation with TfOH produced isoquinolinium trifluoromethanesulfonate, which suggested the formation of isoquinolinium intermediate in the present direct addition reaction.
Published online: 21st April, 2008
■ Enantioselective Synthesis and Proteasome Inhibition of A-Ring Analogs of (-)-Epigallocatechin Gallate (EGCG), the Active Ingredient of Green Tea Extract
Kumi Osanai, Vesna Milacic, Q. Ping Dou, and Tak Hang Chan*
*Department of Chemistry, McGill University, Montreal, Quebec, Canada
Abstract
The A-ring analog compound 8 of (-)-EGCG (1), the active ingredient of green tea, and compound 9, analog of the natural catechin 6 from C. salvifolius, as well as their enantiomers 10 and 11 have been synthesized enantioselectively. They show proteasomal inhibitory activities under cell free conditions, at a potency lower than that of (-)-EGCG. The results suggest that the hydroxyl groups in A-ring of (-)-EGCG play a role in enhancing the activity. The acetylated derivatives of these compounds, 12-15, show cytotoxic activities and proteasomal inhibition after cellular intake, presumably acting as pro-drugs.
Published online: 24th April, 2008
■ Efficient Preparation of 2-Imidazolines from Aldehydes and Ethylenediamines with 1,3-Diiodo-5,5-dimethylhydantoin
Shogo Takahashi and Hideo Togo*
*Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba 263-8522 Japan
Abstract
Various 2-imidazolines were prepared in high yields by reacting aldehydes and ethylenediamines with 1,3-diiodo-5,5-dimethylhydantoin. Moreover, chiral 1,3-bis(imidazolin-2’-yl)benzene and 2,6-bis(imidazolin-2’-yl)pyridines, which function as a chiral ligand, could be directly obtained from corresponding dialdehydes in high yields.
Published online: 8th April, 2008
■ Dechalcogenation of Pentachalcogenadistannabicyclo[3.1.1]heptanes
Masaichi Saito,* Hizuru Hashimoto, and Tomoyuki Tajima
*Department of Chemistry, Graduate School of Science and Engineering, Saitama University, Shimo-okubo, Sakura-ku, Saitama-city, Saitama, 338-8570 Japan
Abstract
Pentathia- and pentaselena-distannabicyclo[3.1.1]heptanes reacted with tributylphosphine to afford tetrathia- and tetraselena- distannabicyclo[2.1.1]hexanes, respectively. The novel heterocyclic framework of a tetrathiadistannabicyclo[2.1.1]hexane was demonstrated by X-ray structural analysis. Structures of a series of pentachalcogena and tetrachalcogena derivatives are discussed.
Published online: 17th April, 2008
■ Total Synthesis of Isoindolobenzazepine Alkaloids, Lennoxamine and Chilenine, Based on Palladium-Catalyzed Reduction of Alkenyl Phosphates
Haruhiko Fuwa* and Makoto Sasaki*
*Laboratory of Biostructural Chemistry, Graduate School of Life Sciences, Tohoku University, 1-1 Tsutsumidori-amamiya, Aoba-ku, Sendai 981-8555, Japan
Abstract
An efficient method for the synthesis of enol ethers and enecarbamates has been developed based on palladium(0)-catalyzed chemoselective reduction of alkenyl phosphates. This method has been applied successfully to the total synthesis of two isoindolobenzazepine alkaloids, lennoxamine and chilenine.
Published online: 21st April, 2008
■ Synthesis, Molecular Structure, and Oxidation Behavior of Exhaustively Methylated Azacalix[6]arene
Koichi Ishibashi, Hirohito Tsue,* Hiroki Takahashi, Satoshi Tokita, Kazuhiro Matsui, and Rui Tamura
*Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
Abstract
The molecular structure and oxidation behavior of an exhaustively methylated azacalix[6]arene have been investigated with the intention of developing high-spin materials. The azacalix[6]arene adopted a distorted 1,3-alternate conformation in the solid state, whereas the conformation was highly flexible in solution at ambient temperature. As a result of the flexible structure in solution, the decreased stability of the corresponding cation radicals was observed, as compared to that of the smaller inflexible homologue yielding stable cation radicals. Both the conformational inflexibility and the steric protection of reactive sites were found to be crucial for stabilizing the oxidized species of this molecular system.
Published online: 28th April, 2008
■ Synthesis of (—)-Talaumidin, a Neurotrophic 2,5-Biaryl-3,4-dimethyltetrahydrofuran Liganan, and Its Stereoisomers
Yoshiyasu Fukuyama,* Kenichi Harada, Tomoyuki Esumi, Daisuke Hojyo, Yumemi Kujime, Naoko Kubo, Miwa Kubo, and Hideaki Hioki
*Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima, 770-8514, Japan
Abstract
The enantioselective total synthesis of a neurotrophic (-)-talaumidin (1) was achieved in 16 steps from 4-benzyloxy-3-methoxybenzaldehyde in ca. 10.7% overall yield. The synthesis features the construction of the two successive chiral centers C-2 and C-3 by Evans asymmetric anti-aldol protocol as well as of the two chiral centers C-4 and C-5 in a highly stereocontrolled fashion by hydroboration/oxidation and epimerization, followed by Friedel-Crafts arylation. Its stereoisomers (2S,3S,4S,5R)-1a and (2S,3S,4R,5S)-1b were also synthesized from a key intermediate 10 with the 2S and 3S configurations.
Published online: 21st April, 2008
■ Stereoselective Synthesis of Pyrrolidin-3-ols from Homoallylamines
Mohamed Medjahdi, José C. González-Gómez, Francisco Foubelo,* and Miguel Yus*
*Department of Organic Chemistry, Faculty of Science, and Institut of Organic Synthesis (ISO), University of Alicante, Apdo. 99, 03080 Alicante, Spain
Abstract
The reaction of enantiomerically pure N-tert-butylsulfinylhomoallylamines 3 (easily prepared by indium mediated allylation of the corresponding N-tert-butylsulfinylaldimine with allyl bromide) with MCPBA in CH2Cl2 at 25 °C leads to epoxysulfonamide derivatives 4 as a ca. 1:1 mixture of diastereoisomers. Cyclization of compounds 4 under basic conditions (K2CO3 in DMF) affords cis- and trans-pyrrolidin-3-ols 5 and 6, respectively.
Published online: 8th May, 2008
■ Structural Aspects of Iodine-Promoted One-Pot Cyclization of O-Bis(methylthio)stilbenes to Thieno[3,2-b]thiophene Derivatives: Synthetic Trials of Tetrathienoacenes from 1,2-Bis(3-methylthiothiophen-2-yl)ethenes
Tatsuya Yamamoto, Eigo Miyazaki, and Kazuo Takimiya*
*Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
Abstract
In this paper, attempted reactions for the synthesis of tetrathienoacenes from 1,2-bis(3-methylthiothiophen-2-yl)ethenes by the iodine-promoted one-pot cyclization reaction were described. X-Ray structural analyses of the precursors indicated that the failure of reactions is closely related to the molecular structures around the reaction moiety, in particular, the bond angles defined by the aromatic ring and the neighboring carbon atom in the ethene moiety. We speculate that the larger angles in the 1,2-bis(3-methylthiothiophen-2-yl)ethenes make the intramolecular nucleophilic attack of the methylthio groups to the iodonium intermediate difficult.
Published online: 24th April, 2008
■ Simultaneous Formation of Antiparallel β-Sheet-like and Type II β-Turn-like Structures Based on Introduction of Dipeptide Chains with Heterochiral Sequence into Ferrocene Scaffold
Toshiyuki Moriuchi,* Takayoshi Nagai, Takashi Fujiwara, Nami Honda, and Toshikazu Hirao*
*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka, Suita, Osaka 565-0871, Japan
Abstract
Simultaneous formation of antiparallel β-sheet-like and type II β-turn-like structures through the intramolecular hydrogen bonds was achieved by the symmetrical introduction of two dipeptide chains with heterochiral sequence (-L-Ala-D-Pro-4APy or -D-Ala-L-Pro-4APy) into the ferrocene scaffold as a central reverse-turn unit. X-ray crystallographic analyses clarified the chirality-organized structure of the ferrocene-peptide bioconjugates, in which the helical chirality of the ferrocene unit was induced. The ferrocene-peptide bioconjugates exhibited an induced circular dichroism (ICD) based on the helical chirality at the absorbance region of the ferrocene moiety.
Published online: 17th April, 2008
■ Design, Synthesis and Evaluation of Antitumor and Antiviral Activities of 5-Amino-1H-[1,2,3]triazolo[4,5-d]pyrimidin-7(6H)-ones (8-Azaguanines) and 7-Amino-1H-[1,2,3]triazolo[4,5-d]pyrimidin-5(4H)-ones (8-Azaisoguanines)
Rafiqul Islam, Noriyuki Ashida, and Tomohisa Nagamatsu*
*Department of Drug Discovery and Development, Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Tsushima-naka, Okayama 700-8530, Japan
Abstract
Preparation of 5-amino-1H-[1,2,3]triazolo[4,5-d]pyrimidin-7(6H)-ones (5a-h) and 7-amino-1H-[1,2,3]triazolo[4,5-d]pyrimidin-5(4H)-ones (8a-n) was accomplished by nitrosative cyclization of the desired 2,5,6-triaminopyrimidine (2a-h) and 4,5,6-triaminopyrimidine derivatives (7a-n) with nitrous acid, respectively. Compounds 5a-h were also prepared by nucleophilic replacement of the methylthio group of 5-methylthio-1H-[1,2,3]triazolo[4,5-d]pyrimidin-7(6H)-one (4) by appropriate amines. Similarly, some 7-amino derivatives (10a-i) were synthesized by replacement of the thiol groups of the 7-thiol derivative (9) by appropriate amines. Antitumor and antiviral activities of the synthesized compounds were evaluated in vitro.
Published online: 28th April, 2008
■ Facile Synthesis of (2-Benzimidazolyl)-1-azaazulenes, (2-Benzothiazolyl)-1-azaazulenes, and Related Compouds and Evaluation of Their Anticancer in vitro Activity
Noriko Yamauchi, Hiroyuki Fujii, Akikazu Kakehi, Motoo Shiro, Masaki Kurosawa, Takeo Konakahara, and Noritaka Abe*
*Applied Molecular Bioscience, Graduate School of Medicine, Yamaguchi University, Yamaguchi 753-8512, Japan
Abstract
Facile syntheses of 2-, 3,- and 8-(2-benzimidazolyl)-1-azaazulenes (2a-c, 5, 7, 9) and 2-, 3-, and 8-(2-benzothiazolyl)-1-azaazulenes (13b-c, 16, 17, 18) were achieved by the condensation of corresponding 1-azaaazulene- carbaldehydes with o-phenylenediamine and 2-aminothiophenol in alcoholic solvents at rt or under reflux under airobic conditions. Reaction of 1-azaazulenecarbaldehyds with 2-aminophenol gave Schiff’s bases (10a-c, 11, 12). Reaction of 2-chloro-1-azaazulene-3-carbaldehyde (1a) with 2-amino- thiophenol in refluxing 1-BuOH gave benzothiazapine-fused 1-azaazulene (20). Reaction of 4-amino-3-mercapto-4H-1,2,4-triazoles (21a-d) with in refluxing 1-BuOH gave triazolothiadizapine-fused 1-azaazulene (22a-d). The structure of trifluolomethyl derivative (22c) was determined by X-ray structure analysis. 3-(2-Benzimidazolyl)-2-chloro-1-azaazulene (2a) showed anticancer activity against HeLa S3 cells (IC50: 5.3 μM).
Published online: 24th April, 2008
■ An Efficient Synthetic Route for a Versatile Ciliapterin Derivative and the First Ciliapterin D-Mannoside Synthesis
Tadashi Hanaya,* Hiroki Baba, Mitsunori Kanemoto, and Hiroshi Yamamoto
*Department of Chemistry, Faculty of Science, Okayama University, Tsushima- naka, Okayama 700-8530, Japan
Abstract
The key precursor, N2-(N,N-dimethylaminomethylene)-1’-O-(4-methoxybenzyl)-3-[2-(4-nitrophenyl)ethyl]ciliapterin (15) was efficiently prepared from D-xylose via an improved route. The first synthesis of 2’-O-(α-D-mannopyranosyl)ciliapterin (2c) was achieved by treatment of 15 with 2,3,4,6-tetra-O-benzoyl-α-D-mannnopyranosyl bromide in the presence of silver triflate and tetramethylurea, followed by removal of the protecting groups.
Published online: 28th April, 2008
■ Development of Tightly Convoluted Polymeric Phosphotungstate Catalysts and Their Application to an Oxidative Cyclization of Alkenols and Alkenoic Acids
Yoichi M. A. Yamada, Haiquin Guo, and Yasuhiro Uozumi*
*Institute for Molecular Science (IMS), Myodaiji, Okazaki, Aichi 444-8787, Japan; ‡RIKEN, Hirosawa, Wako, Saitama 351-0105, Japan
Abstract
Tightly convoluted polymeric phosphotungstate catalysts were prepared via ionic-assembly of H3PW12O40 and poly(alkylpyridinium)s. An oxidative cyclization of various alkenols and alkenoic acids was efficiently promoted by the polymeric phosphotungstate catalyst in aq. H2O2 in the absence of organic solvents to afford the corresponding cyclic ethers and lactones in high yield. The catalyst was reused four times without loss of catalytic activity. The polymeric phosphotungstate was unambiguously characterized by spectro- and microscopic studies (MAS 31P{1H} NMR, IR spectroscopy, elemental analysis, TEM, SEM, and EDS).
Published online: 24th April, 2008
■ Selective Synthesis of Cyclic Phosphoric Acid Diesters through Oxorhenium(VII)-Catalyzed Dehydrative Condensation of Phosphoric Acid with Alcohols
Akira Sakakura, Masayuki Sakuma, Mikimoto Katsukawa, and Kazuaki Ishihara*
*Graduate School of Engineering, Nagoya University, Chikusa, Nagoya, 464-8603 Japan
Abstract
The selective synthesis of phosphoric acid diesters has been achieved through the direct catalytic dehydrative condensation of phosphoric acid with two equivalents of alcohols. The present method works especially well for the synthesis of cyclic phosphoric acid diesters. The combination of perrhenic acid and N-methylbenzylamine efficiently catalyzes the dehydrative condensation of phosphoric acid with equimolar amounts of diols to give cyclic phosphoric acid diesters in excellent yields.
Published online: 1st May, 2008
■ Preparation of 1,3,3a,7a-Tetrahydroisothianaphthene and Its Application to Tetrahydrothiophene-Fused Porphyrin
Yukiko Katsuyama, Eita Yoshida, Hiroki Uoyama, Noboru Ono, and Hidemitsu Uno*
*Division of Synthesis and Analysis, Department of Molecular Science, Integrated Center for Sciences, Ehime University, Matsuyama 790-8577, Japan
Abstract
Dehydrobromination of 5,6-dibromoperhydroisothianaphthene with DBU gave a mixture of 1,3,3a,7a-tetrahydroisothianaphthene and 1,3,3a,4-tetrahydroisothianaphthene in a ratio of 5:1. The former compound acted as an s-cis diene in the Diels-Alder reaction with bis(phenylsulfonyl)ethylene to give an adduct, which was successively converted to tetrahydrothiphene-fused pyrroles and porphyrins.
Published online: 24th April, 2008
■ 2-Alkylidene-1,3-dithiane Monoxides as Activated Alkenes in Rhodium-Catalyzed Addition Reaction of Arylboronic Acids
Suguru Yoshida, Hideki Yorimitsu,* and Koichiro Oshima*
*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
Abstract
2-Methylene-1,3-dithiane 1-oxide reacts with arylboronic acids in the presence of a rhodium catalyst in aqueous dioxane to afford 2-arylmethyl-1,3-dithiane 1-oxides in good yields.
Published online: 12th May, 2008
■ Synthesis of 2,5-Diaminopyrazine Derivatives via Dimerization of 2H-Azirin-3-amines
Maged K. G. Mekhael, Anthony Linden, and Heinz Heimgartner*
*University of Zürich, Institute of Organic Chemistry, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
Abstract
The 2-monosubstituted 2H-azirin-3-amine (5c) was prepared conveniently by subsequent treatment of N-methyl-N-phenylpropanamide in THF with LDA, diphenyl phosphorochloridate (DPPCl), and sodium azide in DMF. In the absence of nucleophiles, the reaction of 5c in THF with BF3·OEt2 at -78°C yields 2,5-dihydro-2,5-dimethyl-3,6-bis(N-methyl-N-phenylamino)pyrazinium tetrafluoroborate (11). Treatment of the latter with NaOH yields the corresponding 2,5-dihydropyrazine derivative (12), whereas dehydrogenation with DDQ leads to 2,5-dimethyl-3,6-bis(N-methyl-N-phenylamino)pyrazine (13). The structures of 12 and 13 were established by X-ray crystallography.
Published online: 21st April, 2008
■ Total Synthesis of an Endothelin Converting Enzyme Inhibitor, TMC-66
Seijiro Hosokawa,* Hitoshi Fumiyama, Hisato Fukuda, Tomohiro Fukuda, Masashi Seki, and Kuniaki Tatsuta*
*Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan
Abstract
The first total synthesis and structural determination of TMC-66, an ECE inhibitor, was achieved in short steps by efficient construction of two tricyclic segments and coupling reactions. The oxidative coupling with phenols attaching to electron-withdrawing groups was realized with a novel copper (II) reagent.