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
Ei-ichi Negishi's Special Issues,Vol. 86, No. 2, 2012
Published online: 3rd September, 2012
■ Synthesis of 2-Acetamido-2,5-dideoxy-5-phosphoryl-D-glucopyranose Derivatives: New Phospha-sugar Analogs of N-Acetyl-D-glucosamine
Tadashi Hanaya,* Masahiro Kawaguchi, Masakazu Sumi, Kazuo Makino, Keiko Tsukada, and Hiroshi Yamamoto
*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan
Abstract
Starting with N-acetyl-D-glucosamine, methyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-xylo-hexofuranosid-5-ulose (18) was prepared in 7 steps. The addition reaction of dimethyl phosphonate to 18, followed by deoxygenation of its 5-hydroxy group, provided the 5-deoxy-5-dimethoxyphosphoryl-D-glucofuranoside derivative (21a). The hydride reduction of 21a, followed by the action of hydrochloric acid and then hydrogen peroxide, afforded the first D-glucosamine analog (23) having a phosphoryl group in the hemiacetal ring. This was converted into the per-O-acetylated N-acetyl-D-glucosamine phospha-sugar (25), while the same treatment of the 5-deoxy-5-dimethoxyphosphoryl-L-idose dimethyl acetal derivative (13b) afforded the N-acetyl-L-idosamine phospha-sugar (29).
Published online: 15th August, 2012
■ SYNTHESIS AND REACTIONS OF SILICON-BRIDGED DITHIENYLBIPHENYLS. FINE TUNING OF ELECTRONIC STATES BY BRIDGING SILICON CHAIN LENGTHS
Joji Ohshita,* Kazuya Murakami, Daiki Tanaka, and Hiroto Yoshida
*Chemistry and Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8527, Japan
Abstract
4,4’-Bis(ethylthienyl)-2,2’-(tetramethyl- and tetrabutyldisilano)biphenyls were prepared by the Migita-Kosugi-Stille coupling reactions of ethyl(trimethylstannyl)thiophene with the corresponding dibromo(disilano)biphenyls. The disilane-bridge of the former underwent oxidation with trimethylamine oxide and Pd-catalyzed benzyne-insertion to form siloxane- and disilylbenzene-bridged biphenyls, respectively. The UV spectra of these compounds showed blue-shifted absorption as the silicon-bridges were elongated. A conjugated polymer with an alternating arrangement of disilanobiphenyl and bithiophene units was also prepared and its oxidation was examined.
Published online: 24th August, 2012
■ SIMPLE SYNTHESES OF 3-TRIFLUOROACETYL-4-QUINOLYLAMINES, SULFIDES, AND ETHERS STARTING FROM N,N-DIMETHYL-4-QUINOLYLAMINE
Etsuji Okada,* Mizuki Hatakenaka, Takushi Sakaemura, Naofumi Shimomura, and Takuro Ashida
*Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
New 3-trifluoroacetyl-4-quinolylamines (2), sulfides (3), and ethers (4) were synthesized in good to high yields by aromatic nucleophilic substitution reactions of N,N-dimethyl-3-trifluoroacetyl-4-quinolylamine (1), which was easily prepared by acylation of N,N-dimethyl-4-quinolylamine with 1-trifluoroacetyl-4-dimethylaminopyridinium trifluoroacetate, with amines, thiols, alcohols, and phenols.
Published online: 24th August, 2012
■ SYNTHESIS OF α-AMINO KETONES AND O-ALKYLOXIMES BY TITANIUM TETRAHALIDE PROMOTED RING-OPENING REACTION OF 2-MONO-SUBSTITUTED AZETIDIN-3-oNES AND THEIR O-ALKYLOXIMES
Shizuka Ariga, Shingo Hata, Daisuke Fukuda, Takafumi Nishi, Iwao Hachiya, and Makoto Shimizu*
*Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Tsu, Mie 514-8507, Japan
Abstract
Synthesis of α-amino ketones and O-alkyloximes has been developed by titanium tetrahalide-promoted ring-opening reactions of 2-mono-substituted azetidin-3-ones and their O-alkyloximes. Regarding the reductive ring-opening reactions of 2-mono-substituted azetidin-3-ones, an appropriate use of TiI4 or TiI4-TiCl4 as a promoter gave α-amino ketones in good yields with high regioselectivities. In TiBr4-promoted ring-opening reactions, while use of 2-mono-substituted azetidin-3-ones as a substrate provided α-amino-α’-bromo ketones generated by the attack of the bromide anion at the less hindered site, those of 2-mono-substituted azetidin-3-one O-alkyloximes proceeded at the more hindered site to give α-amino-α’-bromo ketone O-alkyloximes in good yields.
Published online: 28th August, 2012
■ An Effective Procedure to Promote Aza–Prins Cyclization Reactions Employing a Combination of Ferric Chloride and an Imidazolium Salt in Benzotrifluoride
Chika Osawa, Minami Tateyama, Kensuke Miura, Eiji Tayama, Hajime Iwamoto, and Eietsu Hasegawa*
*Department of Chemistry, Faculty of Sciences, Niigata University, Ikarasi 2-8050, Niigata 950-2181, Japan
Abstract
Aza–Prins cyclization reactions of N-tosyl-3-butenylamine with p-methoxybenzaldehyde, 1-naphthaldehyde and 2-naphthaldehyde take place efficiently using a combination of ferric chloride and 1-butyl-3-methylimidazolium hexafluorophosphate in benzotrifluoride (FeIm–BTF procedure). The new methodology, leading to formation of target N-tosyl-4-chloro-2-substituted piperidines, is superior to the one using 1-butyl-3-methylimidazolium tetrachloroferrate. The FeIm–BTF procedure was also applied to aza–Prins cyclization reactions of other aldehydes. Finally, the effects of imidazolium salts on aza–Prins cyclization reaction promoted by boranetrifluoride-diethyl ether complex, leading to formation of fluorinated piperidines, were explored.
Published online: 10th September, 2012
■ A New Method for Production of Chiral 2-Aryloxypropanoic Acids Using Effective Kinetic Resolution of Racemic 2-Aryloxycarboxylic Acids
Atsushi Tengeiji, Kenya Nakata, Keisuke Ono, and Isamu Shiina*
*Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan
Abstract
We report a novel method for the preparation of 2-aryloxypropanoic acids by kinetic resolution of racemic 2-aryloxypropanoic acids using enantioselective esterification. The usage of pivalic anhydride (Piv2O) as an activating agent, bis(α-naphthyl)methanol ((α-Np)2CHOH) as an achiral alcohol, and (+)-benzotetramisole ((+)-BTM) as a chiral acyl-transfer catalyst enables the effective separation of various racemic 2-aryloxypropanoic acids to afford optically active carboxylic acids and the corresponding esters with high enantioselectivities. Furthermore, theoretical calculations of the transition states required to form the chiral esters successfully proved the enantiomer recognition mechanism of the asymmetric esterification.
Published online: 24th August, 2012
■ AZULENOPENTATHIEPIN: PREPARATION AND CONVERSION INTO AZULENES WITH SULFUR GROUPS AT THE 1- AND 2-POSITIONS
Ohki Sato,* Atsushi Sakai, Masami Aoki, Takaaki Kuramochi, and Juzo Nakayama
*Department of Chemistry, Faculty of Science, Saitama University, Urawa, Saitama 338-8570, Japan
Abstract
Azulenopentathiepin was prepared by the reaction of azulene with elemental sulfur in boiling pyridine. Bis(thiolate) generated from the pentathiepin reacted with electrophiles such as iodomethane, methyl chloroformate, N,N’-carbonyldiimidazole and N,N’-thiocarbonyldiimidazole to afford the corresponding azulene derivatives. Desulfuration of the pentathiepin and the successive reaction with DMAD or a Pd(0) reagent afforded a 1,4-dithiin compound or Pd complexes.
Published online: 21st August, 2012
■ Optional Synthesis of 2- or 5-Substituted 3-Bromopyrroles via Bromine-Lithium Exchange of N-Benzenesulfonyl-2,4-dibromopyrrole
Tsutomu Fukuda and Masatomo Iwao*
*Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
The regioselective bromine–lithium exchange of N-benzenesulfonyl-2,4-dibromopyrrole (6) with n-BuLi followed by treatment with various electrophiles gave 5-substituted 3-bromopyrroles (5) in excellent yields. In contrast, the sequential treatment of 6 with n-BuLi and diisopropylamine followed by quenching with electrophiles produced regioisomeric 2-substituted 3-bromopyrroles (3) selectively. The latter reaction can be rationalized by the rapid equilibration of the C-5 lithio species (4) to the more stable C-2 lithio species (2) in the presence of diisopropylamine.
Published online: 10th September, 2012
■ Synthesis of Versatile Bifunctional Derivatives of Chiral Diamines Obtained through Anchimerically Assisted Nucleophilic Substitution Reactions on Diastereomeric Phenylprolinols
Jorge Vargas-Caporali, Carlos Cruz-Hernández, and Eusebio Juaristi*
*Departamento de Química, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, A.P. 14-740, Avenida IPN 2508, Esquina Ticoman, C.P. 07000 México, D.F., Mexico
Abstract
Diastereomeric [(S)-1-benzylpyrrolidin-2-yl]-(R)-[(phenyl)methanamine] and [(S)-1-benzylpyrrolidin-2-yl]-(S)-[(phenyl)methanamine], were synthesized by selective internal backside nucleophilic substitution of the corresponding activated phenylprolinols. X-Ray diffraction structures of crystalline acetamide derivatives confirmed the anticipated stereochemistry for a SNib reaction mechanism. In order to apply this reaction to the synthesis of bifunctional analogs, a series of fragments such as a thiourea moiety and sulfonamide functions were introduced for the functionalization of the primary amino group in the substrate, obtaining more stable and potentially useful derivatives.
Published online: 1st October, 2012
■ Synthetic Studies on the Role of Substituents at C-3 Position on C3-C4 Bond Cleavage of β-Lactam Ring: Convenient Route for Diastereoselective Synthesis of Pyridin-2-ones
Pardeep Singh, Parvesh Singh, Kewal Kumar, Vipan Kumar, Mohinder P. Mahajan,* and Krishna Bisetty
*Department of Chemistry, Apeejay Stya research foundation, Apeejay Stya University, Apeejay Stya 143005, India
Abstract
The manuscript explicates the detailed synthetic studies on the effect of substituents at C-3 position of 2-azetidinones on the selective C-3/C-4 cleavage resulting in the diastereoselective synthesis of 2-pyridones further corroborated by computational studies. The manuscript assumes significance as the developed protocol does not suffer from the drawbacks associated with conventional methodologies viz. multistep and harsh conditions along with poor regio- and chemo selectivity and thus can be easily manipulated for the synthesis of multi-functionalized pyridine-2-ones.
Published online: 11th September, 2012
■ Chemical Synthesis of Coelenterazine and Its Analogs: New Route toward Four Segment-Couplings
Chun-Ming Chou, Yu-Wen Tung, Meng-I Ling, Diana Chan, Wong Phakhodee, and Minoru Isobe*
*Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang Fu Road, Hsinchu 30013, Taiwan, R.O.C.
Abstract
A novel and improved synthetic route includes four segment couplings toward coelenterazine and its analogs as luminescent molecules. Regio- and chemo-selective cross couplings using palladium catalysts with 5-iodo-3-bromo-2-aminopyrazine have enabled providing various aminopyrazine derivatives having different substituents. The improved synthesis of coelenterazine and its analogs employed advanced condensation with the aminopyrazines using various keto-ketal segments, which resulted in much higher yields to give the final imidazopyrazinone heterocycls than the previous method using keto-aldehydes.
Published online: 3rd September, 2012
■ Palladium-Catalyzed Amination in the Synthesis of Macrobicycles Incorporating Cyclen, Cyclam and Pyridine Moieties
Alexei D. Averin, Kanat S. Tyutenov, Anton V. Shukhaev, Sergei M. Kobelev, Alexei K. Buryak, Franck Denat, Roger Guilard, and Irina Petrovna Beletskaya*
*Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1-3, 119991, Moscow, Russia
Abstract
Palladium-catalyzed amination was successfully applied to the synthesis of macrobicyclic cryptands comprising cyclen or cyclam and pyridine moieties. Starting bis(halopyridylmethyl) substituted cyclen and cyclam were obtained from protected tetraazamacrocycles in good yields and introduced in the catalytic macrocyclization reactions with a number of polyamines and oxadiamines to give target macrobicycles. The yields of macrobicyclic cryptands were shown to be dependent on the cavity size of starting tetraazamacrocycle, on the nature of halogen atom and substitution pattern in the starting compounds, and on the nature of di- and polyamines. The best yields reached 33%.
Published online: 24th August, 2012
■ TOTAL SYNTHESIS OF (+)-HETEROPLEXISOLIDE E
Noriki Kutsumura,* Akito Kiriseko, and Takao Saito*
*Faculty of Science, Department of Chemistry, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan
Abstract
Total synthesis of (+)-heteroplexisolide E has been demonstrated. The synthetic approach exploits the one-pot regioselective Negishi coupling (methylation) and transformation of a β-methallyl alcohol moiety to a branched prenyl group via palladium-catalyzed hydrogenolysis. For the introduction of the 4-oxo-pentylidene side chain, two independent methods were devised: olefin cross metathesis (CM) (route A) and aldol condensation (route B).
Published online: 20th August, 2012
■ CHIRAL PRIMARY AMINO SILYL ETHER ORGANOCATALYST FOR THE ENANTIOSELECTIVE DIELS-ALDER REACTION OF 1,2-DIHYDROPYRIDINES WITH AlDEHYDES
Yuki Sakuta, Yoshihito Kohari, N. D. M. Romauli Hutabarat, Koji Uwai, Eunsang Kwon, Yuko Okuyama, Chigusa Seki, Haruo Matsuyama, Nobuhiro Takano, Michio Tokiwa, Mitsuhiro Takeshita, and Hiroto Nakano*
*Department of Applied Chemistry, Graduate School of Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran, Hokkaido 050-8585, Japan
Abstract
The enantioselective Diels-Alder reactions of 1,2-dihydropylidines with acroleins using a chiral primary amino silyl ether organocatalyst afforded chiral isoquinuclidines with a good chemical yield and excellent enantioselectivity (up to 70%, up to 99% ee).
Published online: 24th August, 2012
■ Mn(OAc)3-Based α’-Oxidative Acetoxylation of N-Trifluoroacetyl Vinylogous Amides
Hong-Yu Lin and Barry B. Snider*
*Department of Chemistry MS 015, Brandeis University, 415 South Street, Waltham, MA 02454-9110, U.S.A.
Abstract
Vinylogous amides 1 and 11 are oxidized by dried Mn(OAc)3 in benzene at 90 °C to pyridines 5 and 12, respectively, whereas the analogous N-trifluoroacetyl vinylogous amides 6 and 13 are oxidized by dried Mn(OAc)3 in benzene at 120 °C to give acetates 7 and 14. The α' oxo radicals that are generated in this oxidation cyclize to proximal double bonds to give tricylic alkenes such as 20.
Published online: 4th September, 2012
■ ASYMMETRIC SYNTHESIS OF 1-ALKYL-2-DEOXYIMINOFURANOSES VIA THE IRIDIUM-CATALYZED INTRAMOLECULAR CYCLIZATION OF AN ALLYLIC CARBONATE
Yoshihiro Natori, Shunsuke Kikuchi, Yuichi Yoshimura, Atsushi Kato, Isao Adachi, and Hiroki Takahata*
*Faculty of Pharmaceutical Sciences, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
Abstract
An asymmetric synthesis of 1-alkyl-2-deoxyiminofuranoses was achieved in which the Ir-catalyzed intramolecular cyclization was the key step. The diastereoselective cyclization converted an allylic carbonate into pyrrolidine derivatives. The α-glucosidase inhibitory activities of the prepared 2-deoxyiminofuranoses were also investigated.
Published online: 2nd October, 2012
■ Tuning the Solubilities of Bis-triazinylphenanthroline Ligands (BTPhens) and Their Complexes
Dominic M. Laventine, Ashfaq Afsar, Michael J. Hudson, and Laurence M. Harwood*
*Department of Chemistry, University of Reading, Reading RG6 6AD, U.K.
Abstract
A series of bis-triazinylphenanthroline ligands (BTPhens) was synthesized by modifying the triazine substituents. It was found that varying these substituents altered the solubilities of the ligands in a number of non-polar solvents. Thus C5-BTPhen showed significantly higher solubility in octanol than C1-BTPhen. The high solubility of C5-BTPhen and its complexes was exploited to facilitate the NMR titration experiments. These experiments shown that the dominant species in solution were the 1:2 complexes [Ln(III)(BTPhen)2], even at high Ln concentrations, and that the relative stability of the 2:1 to 1:1 BTPhen-Ln complexes varied with different lanthanides. C5-BTPhen therefore shows considerable promise for a once-through selective actinide separation process.
Published online: 12th October, 2012
■ Chemistry of Polyhalogenated Nitrobutadienes, 12: Synthesis of Novel, Highly Substituted Bi- and Tricyclic 5,6,7,8-Tetrahydro-4H-chromen-5-ones
Viktor A. Zapol'skii, Eva-Janina Vogt, Mimoza Gjikaj, and Dieter E. Kaufmann*
*Institute of Organic Chemistry, Clausthal University of Technology, Leibnizstrasse 6, D-38678 Clausthal-Zellerfeld, Germany
Abstract
Knoevenagel condensation of 3,4-push-pull-substituted thiophene-2-carbaldehydes 4 with malononitrile gives the gem-dicyanovinyl-thiophenes 5, followed by a Michael addition of dimedone and a subsequent cyclization to 4-(2-thienyl)-5,6,7,8-tetrahydro-4H-chromen-5-ones 6. Protonolysis of the latter in methanol led to a mixture of four heterocycles 7-10, the main product being the novel tricyclic 9-(2-thienyl)-6,7-dihydro-5H-thieno[3,2-b]chromen-8(9H)-one derivative 7. A mechanism of the protonolysis reaction is proposed, the structures of the two main products have been confirmed by X-ray analysis.
Published online: 15th October, 2012
■ Specific Inhibitors of Puromycin-Sensitive Aminopeptidase with a 3-(Halogenated Phenyl)-2,4(1H,3H)-quinazolinedione Skeleton
Yotaro Matsumoto,* Tomomi Noguchi-Yachide, Masaharu Nakamura, Yusuke Mita, Akiyoshi Numadate, and Yuichi Hashimoto*
*Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
Abstract
Specific puromycin-sensitive aminopeptidase (PSA) inhibitors with a 3-(halogenated phenyl)-2,4(1H,3H)-quinazolinedione skeleton were prepared and their structure–activity relationships were investigated. The nature (F, Cl or Br), number and position(s) of the halogen atom(s) introduced into the 3-phenyl group were concluded to be critical determinants of the inhibitory activity.
Published online: 18th October, 2012
■ New Results on the Photoreactivity of 5-Fluoro-1,3-dimethyluracil with Methoxylated Naphthalenes
Kazue Ohkura,* Kazuya Aizawa, Rie Mukaida, Hiromichi Akizawa, and Koh-ichi Seki*
*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
Abstract
Photocycloaddition of 5-fluoro-1,3-dimethyluracil (5-FDMU) with various methoxy and dimethoxynaphthalenes was investigated. Reaction of 5-FDMU with 1,x-dimethoxynaphthalenes (x = 4-7) gave rise to the selective formation of cycloadducts, conjugated arylpropenylidene-1,3-diazin-2-ones, which were derived from an initially formed oxetane moiety via the Paterno-Büchi reaction cycloadduct. The present study shows that the presence of a methoxy substituent on the α−position in naphthalene is essential for the formation of products through the Paterno-Büchi reaction. This unique photoreaction involving formation of an oxetane between 5-FDMU and a naphthalene ring, followed by a concomitant disruption of the initially formed oxetane moiety and an aromatic ring of naphthalene moiety, can be regarded as a novel aromatic Paterno-Büchi reaction.
Published online: 22nd November, 2012
■ ASYMMETRIC INTRAMOLECULAR CONJUGATE ADDITION OF α-AMINO ACID DERIVATIVES VIA RACEMIZATION-FREE EQUILIBRIUM OF INTERMEDIARY CHIRAL ENOLATES
Daiki Monguchi, Tomoyuki Yoshimura, Kazuyuki Irie, Kazuhiro Hayashi, Swapan Majumdar, Takahiro Sasamori, Norihiro Tokitoh, and Takeo Kawabata*
*Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
Abstract
A highly enantioselective route to a multi-substituted indoline derivative via intramolecular conjugate addition of an α-amino acid derivative has been developed. Enantioselectivity of the reaction was almost independent from the temperature, while the diastereoselectivity was totally dependent on the temperature. High diastereomeric ratios observed at the higher temperatures were assumed to be the results from an equilibrium process between axially chiral enolate intermediates.
Published online: 28th November, 2012
■ Application of Zirconacyclopentadienes (Metalla-heterocycles) and Cross-Coupling for the Convenient Preparative Method of 6,13-Disubstituted Pentacene
Zhiying Jia, Shi Li, Kiyohiko Nakajima, Ken-ichiro Kanno, Zhiyi Song, and Tamotsu Takahashi*
*Catalysis Research Center and Graduate School of Pharmaceutical Science, Hokkaido University, Sapporo 001-0021, Japan
Abstract
Iodination of zirconacyclopentadiene derivative gave diiododiene derivative. The product was lithiated with t-BuLi and treated with diiodonaphthalene successively to afford 6,13-bis(trimethylsilyl)-5,14-dihydropentacene. A 6,13-diiodo-5,14-dihydropentacene was synthesized by iodination of 6,13-bis(trimethylsilyl)-5,14-dihydropentacene with ICl. This diiododihydropentacene was used for the introduction of substituent at 6 and 13 positions by the cross-coupling reactions with Pd catalyst. After aromatization by a combination of DDQ and γ-terpinene or triethylamine, 6,13-disubstituted pentacene derivatives were synthesized.
Published online: 4th September, 2012
■ Reactions of 3-[Bis(methylthio)methylene]-2(3H)-imidazo[1,2-a]pyridinones with Quinolinium and Isoquinolinium N-Unsubstituted Aminides
Akikazu Kakehi,* Takashi Abe, Hiroyuki Suga, and Kennosuke Itoh
*Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
Abstract
1,3-Dipolar cycloadditions of 3-[bis(methylthio)methylene]- 2(3H)-imidazo[1,2-a]pyridinones with quinolinium and isoquinolinium N-unsubstituted aminides were investigated and the corresponding spiro[imidazo[1,2-a]pyridine-3,3’-pyrazolo[1,5-a]quinoline] and spiro[imidazo[1,2-a]pyridine-3,3’-pyrazolo[5,1-a]isoquinoline] derivatives were formed by way of the elimination of methanethiol from the primary adducts.
Published online: 28th September, 2012
■ GRISEOVIRIDIN AND CYCLIC HYDROXAMATES FOUND IN A SCREENING PROGRAM FOR Wnt SIGNAL INHIBITOR
Yuuya Tamai, Kazufumi Toume, Midori A. Arai, and Masami Ishibashi*
*Department of Natural Products Chemistry, Graduate School of Pharmaceutical Science, Chiba University, 1-8-1 Inohana, Chuo, Chiba, Japan
Abstract
A screening study using a luciferase assay to identify natural products which inhibit Wnt signaling was carried out. Bioassay-guided fractionation of the culture broth and mycelia of actinomycetes CKK748 and CKK784, led to the isolation of griseoviridin (1), and four cyclic hydroxamates (4-7) as active compounds. 1, 4, and 5 inhibited TCF/β-catenin transcriptional activity with IC50 values of 8.2-14 μM.
Published online: 21st August, 2012
■ Furosonin, a Novel Hydrolyzable Tannin from Geranium thunbergii
Shoko Taniguchi, Ryouta Nogaki, Li-Ming Bao, Teruo Kuroda, Hideyuki Ito, and Tsutomu Hatano*
*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan
Abstract
Furosonin (2), a novel hydrolyzable tannin, was isolated from Geranium thunbergii (Geraniaceae) leaves, and the structure was determined based on spectroscopic data. The effects of geraniin (1), furosonin (2), and related hydrolyzable tannins on antibiotic resistance were examined, and repandusinic acid A (4) was found to suppress oxacillin resistance of methicillin-resistant Staphylococcus aureus.
Published online: 17th August, 2012
■ Short and Stereocontrolled Cyclic Polyglycerols Synthesis Using BF3·OEt2 Mediated Intramolecular Epoxide-Opening Reaction
Masahiro Hamada,* Takao Kishimoto, and Noriyuki Nakajima
*Department of Biotechnology, Faculty of Engineering, Toyama Prefectural University, 5180 Kurokawa, Kosugi, Toyama 939-0398, Japan
Abstract
We developed a new method for the stereocontrolled synthesis of cyclic oligoglycerols. Optically pure solketal and epichlorohydrin were coupled with allyl alcohol under aqueous basic conditions to construct a linear triglycerol skeleton. After subsequent steps, the epoxy alcohol (7) obtained was treated with a catalytic amount of BF3·OEt2 in CH2Cl2 to produce in a high yield of the desired cyclic triglycerol through a regioselective, intramolecular epoxide ring-opening reaction.
Published online: 24th August, 2012
■ Synthesis of a Novel Non-Benzenoid Quinone, 3,10-Dihydro-2,4-dimethyl-7,13-methanocyclohepta[11]annulene-3,10-dione, from 8H-7,9-Bis(methoxycarbonyl)-5,11-methano[11]annuleno[c]furan-8-one
Shigeyasu Kuroda,* Naoko Matsumoto, Yanmei Zhang, Ryuta Miyatake, Yurie Fujiwara, and Mitsunori Oda*
*Department of Chemistry, Faculty of Science, Shinshu University, Asahi, Matsumoto 390-8621, Japan
Abstract
8H-7,9-Bis(methoxycarbonyl)-5,11-methano[11]anuleno[c]furan- 8-one (3) undergoes [4+3] cycloaddition with an oxyallyl species generated from 2,4-dibromo-3-pentanone in the presence of KI and copper, followed by dehydration in fluorosulfuric acid to give cyclohepta[11]annulenedione diester 9. After hydrolysis of the ester groups, decarboxylation yielded the title quinone 6. The 1H NMR spectrum of 6 in D2SO4 indicates generation of its protonated dicationic species.
Published online: 20th September, 2012
■ Computational Investigation of a Photo-Switchable Single-Molecule Magnet Based on a Porphyrin Terbium Double-Decker Complex
Tomoko Inose, Daisuke Tanaka, and Takuji Ogawa*
*Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Matikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
Abstract
Based on the finding that switching of single molecule magnetic property (SMM) is possible for porphyrin-TbIII double-decker complexes by protonation and deprotonation, we performed a theoretical consideration of photo induced switching of SMM in a porphyrin-quinone dyad by density functional theory (DFT)-based calculations. In the excited state, proton (or hydrogen) transferred structure (*por-QH) is only 1.26 Kcal/mol higher in energy than that of the starting structure (*porH-Q), which suggests that the proton (or hydrogen) transfer in the excited state is possible.
Published online: 4th September, 2012
■ DIVERSITY ORIENTED APPROACH TO 9-ARYL-SUBSTITUTED NAPHTHOXEPINE DERIVATIVES VIA CLAISEN REARRANGEMENT, RING-CLOSING METATHESIS AND SUZUKI–MIYAURA CROSS-COUPLING AS KEY STEPS
Sambasivarao Kotha,* Venu Srinivas, and Nimita G. Krishna
*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India
Abstract
A novel route to a variety of 9-aryl-substituted naphthoxepine derivatives is described starting with 6-bromo-2-naphthol via Claisen rearrangement (CR), ring-closing metathesis (RCM) and Suzuki−Miyaura (SM) cross-coupling as key steps.
Published online: 16th August, 2012
■ SYNTHESIS OF A NEW OSELTAMIVIR DERIVATIVE THROUGH LATE-STAGE CATALYTIC C–H FUNCTIONALIZATION
Kenta Saito and Motomu Kanai*
*Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Abstract
N-Boc-protected oseltamivir 5 was converted to olefin insertion product 4 via a ruthenium-catalyzed C(sp2)–H functionalization reaction using its ester functionality as a directing group. The addition of a catalytic amount of (p-CF3C6H3)3P in the presence of the RuH2(CO)(PPh3)3 catalyst significantly improved the yield for this specific conversion. Tamao-Fleming oxidation followed by deprotection concisely produced a new oseltamivir analog 16.