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
Akira Suzuki's Special Issues,Vol. 80, No. 2, 2010
Published online: 15th September, 2009
■ Design of Reaction Media for Nucleophilic Substitution Reactions by Using a Catalytic Amount of an Amphiphilic Imidazolium Salt in Water
Keisuke Asano and Seijiro Matsubara*
*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoudai-katsura, Nishikyo, Kyoto 615-8510, Japan
Abstract
Molecules of an amphiphilic imidazolium salt assemble in water to form a hydrophobic membrane including an interface consisting of ammonium species. Such an interface works as a reaction medium like an ionic liquid. We used the medium for nucleophilic substitution reactions between alkyl halides and anionic nucleophiles. This procedure allowed the reactions to proceed efficiently in water without any organic solvent.
Published online: 2nd September, 2009
■ Synthesis of (±)-Heliannuol D Based on Platinum Catalyzed Regioselective Addition of Arylboronic Acids to Allenes
Mayu Osaka, Makoto Kanematsu, Masahiro Yoshida, and Kozo Shishido*
*Graduate School of Pharmaceutical Sciences, University of Tokushima, Sho-machi, Tokushima 770-8505, Japan
Abstract
An alternative total synthesis of (±)-heliannuol D has been achieved in 13 steps and 6.9% overall yield from the arylboronic acid 9. The synthesis applies the previously developed regiocontrolled addition of arylboronic acids to allenes using a platinum catalyst to install the C5 carbon chain on the aryl ring.
Published online: 2nd September, 2009
■ Synthesis of 6-Hydroxymethylpterin α- and β-D-Glucosides
Tadashi Hanaya,* Hiroki Baba, Kazumasa Ejiri, and Hiroshi Yamamoto
*Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan
Abstract
The key precursor, N2-(N,N-dimethylaminomethylene)-6-hydroxymethyl-3-[2-(4-nitrophenyl)ethyl]pterin (11) was efficiently prepared from 2,5,6-triamino-4-hydroxypyrimidine (8) in 5 steps. The first, unequivocal synthesis of 6-hydroxymethylpterin α-D-glucoside (6a) was achieved by treatment of 11 with 4,6-di-O-acetyl-2,3-di-O-(4-methoxybenzyl)-α-D-glucopyranosyl bromide (16) in the presence of tetraethylammonium bromide and N-ethyldiisopropylamine, followed by removal of the protecting groups, while 6-hydroxymethylpterin β-D-glucoside (6b) was prepared by means of selective glycosylation of 11 with 2,3,4,6-tetra-O-benzoyl-α-D-glucopyranosyl bromide (12) in the presence of silver triflate and tetramethylurea.
Published online: 8th September, 2009
■ Synthetic Study Directed toward Derivatives of Biologically Active Indolo[2,3-a]carbazole
Masako Sato, Yoshiaki Suzuki, Fumio Yamada, and Masanori Somei*
*Faculty of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
Abstract
Various derivatives of (6R*,6aR*)-6-chloro-6a-hydroxy-5,6,6a,12-tetrahydroindolo[2,3-a]carbazole-5-one (8) and 6-cyano-5-hydroxyindolo[2,3-a]carbazole (9) are prepared. Preparations of (6R*,6aR*,11aR*)-6-chloro-11a-cyano-6a-hydroxy- (11) and 12-substituted 6-(Z)-aminomethylidene-5,6,6a,11,11a,12-hexahydroindolo[2,3-a]carbazole-5-ones (15) are also reported.
Published online: 8th September, 2009
■ Novel Carbohydrazide and Hydrazone Biomarkers Based on 9-Substituted Acridine and Anthracene Fluorogens
Zdenka Bedlovičová, Ján Imrich,* Pavol Kristian, Ivan Danihel, Stanislav Böhm, Danica Sabolová, Mária Kožurková, Helena Paulíková, and Karel D. Klika
*Institute of Chemistry, Faculty of Science, P. J. Šafárik University, Moyzesova 11, SK-041 67 Košice, Slovak Republic
Abstract
Three series of carbohydrazides or hydrazones bearing either acridine or anthracene pharmacophores were synthesized as potential noncovalent DNA-binding antitumor agents. Carbohydrazides with an acridine or anthracene moiety were prepared from appropriate acridine or anthracene carbaldehydes via cyclocondensation with selected hydrazides whilst hydrazones with a 10H-acridin-9-ylidene moiety were obtained by condensation of (acridin-9-yl)hydrazine with various aldehydes or ketones. The spectroscopic properties of the first two series revealed efficient fluorescence implying that the compounds could be amenable for use as biomarkers. The structures of the compounds were characterized by spectral methods (UV-vis, fluorescence, IR, and 1H, 13C, and 2D NMR) and quantum-chemical calculations (DFT, ZINDO, and AM1). The first carbohydrazide series was also tested against human leukemia cell line HL-60 wherein the phenyl-substituted derivative was found to possess the highest activity.
Published online: 3rd September, 2009
■ Synthetic Study on Clutiolide Based on a Remote Chelation Controlled Ireland-Claisen Rearrangement
Jun Ishihara,* Okihisa Tokuda, Kazunori Shiraishi, Yukihiro Nishino, Keisuke Takahashi, and Susumi Hatakeyama*
*Department of Pharmaceutical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
A methodology feasible for the stereoselective synthesis of clutiolide, a secolabdane diterpene from Clutia abyssinica, was developed based on a remote chelation controlled Ireland-Claisen rearrangement.
Published online: 9th September, 2009
■ Structure-Activity Relationships of Synthesized Procyanidin Oligomers: DPPH Radical Scavenging Activity and Maillard Reaction Inhibitory Activity
Akiko Saito and Noriyuki Nakajima*
*Biotechnology Research Center, Toyama Prefectural University, 5180 Kurokawa, Kosugi, Toyama 939-0398, Japan
Abstract
Procyanidins are known as condensed tannins and/or oligomeric flavonoids, and are present in many edible plants and show interesting various biological activities. We previously developed and reported a simple and versatile method of synthesizing procyanidin oligomers consisting of (–)-epicatechin and (+)-catechin. Here, we report the structure–activity relationships (SAR) between the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and Maillard reaction inhibitory activities of various procyanidin oligomers synthesized, including dimers, trimers, tetramers, pentamers, 3-O-substituted oligomers, and other artificial oligomers.
Published online: 16th September, 2009
■ Three-Component Reactions with 3-Phenyl-1-azabicyclo[1.1.0]butane, Dimethyl Dicyanofumarate, and Primary Aromatic Amines
Grzegorz Mlostoń* and Heinz Heimgartner*
*Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190,
CH-8057 Zürich, Switzerland
Abstract
The three-component reaction of 3-phenyl-1-azabicyclo[1.1.0]butane (1a) with 2,3-dicyanofumarates (DCFM) and primary aromatic amines in dichloromethane at room temperature yielded mixtures of (Z)-2-arylamino-3-cyanofumarates (7) and the corresponding (E)-2-(azetidin-1-yl)-3-cyanomaleates (6) and (9). In the case of anisidine (8d), higher oligomers containing three or four azetidine residues, e.g. 10a, were also formed. With more nucleophilic aliphatic amines, only 1:1 adducts of type 7 were obtained. The reaction course can be rationalized by the formation of intermediate zwitterions (11) via addition of the N-nucleophiles onto DCFM. The results show that the nucleophilicity of 1a toward DCFM is lower than that of aliphatic amines but exceeds that of aromatic amines.
Published online: 1st October, 2009
■ Unusual Reactions of the Highly Strained Macrocycles with Lithium Salts: Anion Control for the Reaction Rates and Elucidation of the Properties of Their Lithium Complexes
Junko Morita, Shinji Tsuchiya, Nao Yoshida, Nirei Nakayama, and Shojiro Ogawa*
*Center of Environmental Science for Human Life, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
Abstract
The complexation reactions of dicyano monoalkyl tetraaza macrocycle 3b with lithium salts (Li+X-) and the properties of resulting macrocycle 3b-Li+ X- complexes were examined in detail by means of 1H-NMR spectroscopy, because unsymmetrical macrocycle 3b has exhibited intriguing features, such as high selectivity for binding to the Li+ ion. The following noticeable facts were found; the reaction rates of complexation are heavily controlled by the properties of anion (X-) and the spectroscopic properties of macrocycle 3b-Li+ X- complexes are also changed by the anion. The major origin for the unusual Li+ complexation reactions and the specific behavior of Li+ complexes would come from the unique properties of metal free macrocycle 3b, because macrocycle 3b has a strong intramolecular hydrogen bond in the macrocyclic ring and the highly strained macrocyclic ring by unsymmetrical structure consisting of nonplanar and planar moieties.
Published online: 9th September, 2009
■ Reaction Behavior of Cumulene: Diels–Alder, Friedel–Crafts, and Pd-Catalyzed Domino Reactions
Tomohiro Asakawa, Mie Iinuma, Yuko Wakasugi, Mayumi Kuno, Takumi Furuta,* Satoshi Fujii, Kiyoshi Tanaka, and Toshiyuki Kan*
*Laboratory of Synthetic Organic & Medicinal Chemistry, Schol of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
Abstract
Diels–Alder, Friedel–Crafts, and domino reactions mediated by Pd-catalyst of [3]cumulene 1 were investigated. Although the Diels–Alder reaction with cyclopentadiene occurred selectively on the C2, C3 double bond to give tetrasubstituted allenyl products, the Friedel–Crafts type addition of electron-rich heteroaromatics and subsequent protonation cleanly occurred on the C3, C4 double bond to afford tetrasubstituted conjugated dienes. In the Heck reaction with aryl iodide, the arylpalladium species was selectively inserted into the C3, C4 double bond and a subsequent C–H activation reaction with a neighboring phenyl group gave indene derivatives with a tetrasubstituted olefin moiety. Furthermore, Pd-catalyzed domino cyclization–allylation reaction of in situ generated [3]cumulene alkoxide afforded tetrasubstituted furan.
Published online: 9th September, 2009
■ Non-Natural Nucleosides Based on 1,2,4-Triazolo[1,5-a]pyrimidin-7-ones
Oleg N. Chupakhin,* Tatiana S. Shestakova, Sergey L. Deev, Oleg S. Eltsov, and Vladimir L. Rusinov
*I. Ya. Postovski Institute of Organic Synthesis, Urals Branch, Russian Academy of Sciences, 22/20, S. Kovalevskoi, Akademicheskaya st., Ekaterinburg
GSP-147, 620041, Russia
Abstract
Two methods for synthesis of new nucleosides bearing 6-phenyl-1,2,4-triazolo[1,5-a]pyrimidin-7-ones as a base have been developed. The first one includes Vorbrüggen glycosylation reaction. The second method, which is effective for synthesis of acyclic nucleosides, is based on the condensation between sodium salts of 6-phenyl-1,2,4-triazolo [1,5-a]pyrimidin-7-ones and 4-bromobuthyl acetate or (Z)-4-bromobut-2-en-1-yl acetate.
Published online: 18th September, 2009
■ Synthesis of Tetrabenzoporphyrins Fused with Fluoranthenes
Jun Nakamura, Tetsuo Okujima,* Yuya Tomimori, Naoki Komobuchi, Hiroko Yamada, Hidemitsu Uno, and Noboru Ono
*Department of Chemistry and Biology, Graduate School or Science and Engineering, Ehime University, Matsuyama 790-8577, Japan
Abstract
Tetrabenzoporphyrins fused with fluoranthenes were prepared by the retro Diels-Alder reaction of the precursors composed of a porphyrin and four fluoranthenes connected with bicyclo[2.2.2]octadiene (BCOD). These porphyrins exhibited the Soret (480–494 nm, ε = 243,000–277,000) and intense Q bands (739–760 nm, ε = 375,000–509,000). Free bases and Zn complexes of them fluoresce at 760 nm and 746 nm with small Storks shifts and high quantum yields of 30 and 10 %, respectively.
Published online: 13th October, 2009
■ Memory of Chirality in the Electrochemical Oxidation of Thiazolidine-4-carboxylic Acid Derivatives
George Ng’aNg’a Wanyoike, Yoshihiro Matsumura, Masami Kuriyama, and Osamu Onomura*
*Department of Pharmaceutical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
Memory of chirality in the electrochemical oxidation of thiazolidine-4-carboxylic acid derivatives was observed. The relatively larger size of sulphur atom than the oxygen atom for oxazolidine-4-carboxylic acid derivative may slightly improved the enantioselectivities of the oxidized products. The bulkier penicillamine derivative 1c furnished 2c with much better enantioselectivity (91% ee) than that of the cysteine derivative 2b (85% ee). The presence of two extra dimethyl groups, for the penicillamine derivative improved the enantioselectivities of the thiazolidine derivatives from 85% ee to 91% ee.
Published online: 4th September, 2009
■ Thermal Behavior of Bicyclo[2.2.2]octadiene-Installed Precursors for 2H-Anthra[2,3-c]pyrroles and Anthra[2,3-c]thiophene
Hiroki Uoyama, Cai Chenxin, Hiroyuki Tahara, Yusuke Shimizu, Hideki Hagiwara, Yasuaki Hanasaki, Hiroko Yamada, Tetsuo Okujima, and Hidemitsu Uno*
*Integrated Center for Science, Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan
Abstract
4,11-Ethano-4,11-dihydro-2H-anthra[2,3-c]pyrrole and 4,11-ethano-4,11-dihydroanthra[2,3-c]thiophene derivatives were prepared from the corresponding bicyclo[2.2.2]octadiene-fused five-membered heterocycles by the Diels-Alder reaction with in situ generated α,α’-dibromo-o-xylylene derivatives. Their thermogravimetric analyses showed evapolation without formation of 2H-anthra[2,3-c]pyrrole and anthra[2,3-c]thiophene derivatives under the atmospheric pressure.
Published online: 15th September, 2009
■ Synthesis and Properties of Dicarboximide Derivatives of Perylene and Azaperylene
Yukinori Nagao,* Tatsurou Yoshida, Koji Arimitsu, and Kozo Kozawa
*Department of Industrial Chemistry, Faculty of Science and Technology, Science University of Tokyo, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
Abstract
The N-alkyl dicarboximide derivatives of naphthylisoquinoline and binaphthalene were prepared by the hetero coupling reaction of the corresponding N-alkyl dicarboximide derivatives of stannylnaphthalene with bromodimethyisoquinoline and bromodimethylnaphthalene, respectively. The ring closing of the N-hexyl derivatives of naphthylisoquinoline and binaphthalene produced the N-hexyldicarboximide derivatives of azaperylene and perylene having the same substituents, respectively. The absorption spectra and fluorescence spectra of the azaperylene and perylene derivatives were investigated.
Published online: 27th August, 2009
■ Stille Cross-Coupling Reactions of Aryl Mesylates and Tosylates Using a Biarylphosphine Based Catalyst System
John R. Naber, Brett P. Fors, Xiaoxing Wu, Jonathon T. Gunn, and Stephen L. Buchwald*
*Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, U.S.A.
Abstract
A catalyst system for the Stille cross-coupling reactions of aryl mesylates and tosylates is reported. Using the combination of Pd(OAc)2, XPhos, and CsF in t-BuOH an array of aryl and heteroaryl sulfonates were successfully employed in these reactions. Morever, heteroarylstannanes, such as furyl, thienyl, and N-methylpyrrolyl, which are often prone to decomposition, were efficiently coupled under these conditions. Ortho-substitution on the stannane coupling partner was well tolerated; however, the presence of ortho substituents on the aryl sulfonates greatly reduced the efficiency of these reactions.
Published online: 18th September, 2009
■ Quinone Dimers Connected by 1,4-Phenylene and 2,5-Thienylene Moieties as a π Linker
Naoto Hayashi,* Teru Sakakibara, Takahiro Ohnuma, Junro Yoshino, and Hiroyuki Higuchi
*Department of Chemistry, Graduate School of Science and Engineering, Toyama University, Gofuku 3190, Toyama 930-8555, Japan
Abstract
The synthesis and characterization of quinone dimers connected by 1,4-phenylene (QPQ) and 2,5-thienylene (QTQ) linkers are described. QPQ and QTQ were synthesized by means of Suzuki coupling and subsequent oxidation. Significant bathochromic shifts were observed in the electronic absorption spectra of QPQ and QTQ as compared to that of the quinine dimers without a linker. In addition, cyclic voltammetry and DFT calculations demonstrated that QTQ was a stronger electron acceptor than QPQ due to its planar structure, even though QTQ contains an electron-rich thiophene ring.
Published online: 13th October, 2009
■ RhCl3-Catalyzed Disulfide Exchange Reaction of Insulin and Dithiodiglycolic Acid
Mieko Arisawa, Manabu Kuwajima, Atsushi Suwa, and Masahiko Yamaguchi*
*Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Aoba-ku, sendai 980-8578, Japan
Abstract
RhCl3 catalyzed the alkylthio exchange reaction of insulin and dithiodiglycolic acid in water under homogeneous conditions. Insulin was rapidly consumed, and mono- and bis-exchanged insulin were formed along with the disulfide exchanged A and B chain. The disulfide bond at the A7/B7 was initially exchanged, which was followed by the A6/A11 and A20/B19 disulfides.
Published online: 1st October, 2009
■ Synthesis and Evaluation of Novel 3,4-Epoxypiperidines as Efficient DNA Alkylating Agents
Yuji Kawada, Tetsuya Kodama, Kazuyuki Miyashita, Takeshi Imanishi, and Satoshi Obika*
*Graduate School of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 560-0871, Japan
Abstract
3,4-Epoxypiperidine derivatives are novel DNA alkylating agents based on an active site of the antitumor antibiotics azinomycins A and B. A 3,4-epoxypiperidine library was constructed containing derivatives with a variety of functional groups at C5 via Huisgen reaction, and DNA cleavage activity was examined. Results revealed a more active derivative than any 3,4-epoxypiperidines previously reported.
Published online: 18th September, 2009
■ Synthesis of Some New Biheterocycles by a One-Pot Suzuki-Miyaura Coupling Reaction
Mandar Deodhar, David StC. Black,* Daniel Shiu-Hin Chan, and Naresh Kumar*
*School of Chemistry, The University of New South Wales, Sydney 2052, Australia
Abstract
Halogenated indoles, benzofurans and flavones were subjected to a one-pot Suzuki-Miyaura coupling reaction to generate a series of new biheterocycles. The methodology may be readily adapted to the synthesis of a wide variety of substituted biheterocycles.
Published online: 2nd October, 2009
■ Synthesis and Photophysical Properties of 2,3,5,6,7,8-Hexasilabicyclo[2.2.2]octan-1-yl-substituted Arenes
Masaki Shimizu,* Tomoaki Kawaguchi, Hisashi Nakagawa, Katsunari Oda, and Tamejiro Hiyama*
*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoudai-katsura, Nishikyo, Kyoto 615-8510, Japan
Abstract
Incorporation of 2,2,3,3,5,5,6,6,7,7,8,8-dodecamethyl-2,3,5,6,7,8-hexasilabicyclo[2.2.2]octan-1-yl moiety into such chromophores as biphenyl, terphenyl, stilbene, and tolan was found to induce bathochromic shifts of absorption and fluorescence spectra, compared with those of the parent chromophores. Moreover, enhancement of the molar extinction coefficients and the fluorescence quantum yields by the substitution was also observed. These results indicate that σ–π conjugation between the polysilacage moiety and the chromophores is operative. Theoretical study of the polysilacage-substituted chromophores is also presented.
Published online: 15th October, 2009
■ Microwave-Assisted Synthesis of 3-Methylisothiazolo[5,4-b]pyridine and Various 2-Amino Derivatives of Thieno[2,3-b]pyridine and 1-(2-Aminopyridin-3-yl)ethanone
Haribabu Ankati and Edward R. Biehl*
*Chemistry Department, Southern Methodist University, Dallas, TX 75275-0314, U.S.A.
Abstract
Various 2-amino derivatives of thieno[2,3-b]pyridin-2-amine (3a-g) were prepared in fair to good yields (30-76%) by subjecting 1-(2-chloropyridin-3-yl)ethanone (1) and appropriate primary amine (2a-g) to microwave heating at 90-120 ˚C for 15-20 min in the presence of elemental sulfur, NaOAc, and DMF. Lower yields (4-15%) of the secondary 2-amino derivatives of 1-(pyridin-3-yl)ethanone product (4a-g) were also obtained. However, when the microwave-assisted reactions were carried out on primary (2b-h) and secondary amines (2i-o) in the absence of elemental S at 100-200 ˚C for 15-20 min, the respective secondary 2-amines (4b-h) and tertiary 2-amines (4i-o) of 1-(pyridin-3-yl)ethanones were obtained in good to excellent yields (61-98%). Finally, when 1 subjected to microwave heating at 120 ˚C for 15 min in the presence of elemental sulfur, NH¬4Cl, NaOAc, and DMF, 3-methyl- isothiazolo[5,4-b]pyridine (5) was obtained in 79% yield. Possible mechanisms for the formation of compounds 3-5 are presented.
Published online: 28th September, 2009
■ Application of Sugar Allyltin Derivatives for the Preparation of Heterocyclic Compounds
Marta Magdycz, Piotr Cmoch, and Sławomir Jarosz*
*Institute of Organic Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, P.O.Box 58, PL-01-224 Warszawa 42, Poland
Abstract
Controlled fragmentation of sugar allyltin, derivative of D-glucose, provided the eight carbon atom synthon: (2R,3S,4R)-tris(benzyloxy)oct-5,7-diene, which was used for the preparation of complex heterocyclic compounds. First step involved formation of the corresponding oxime, which underwent – under high pressure – the oxime/olefin cyclization (the alternative Diels-Alder product was not formed). Proper functionalization of the latter led to the tricyclic product.
Published online: 16th October, 2009
■ Synthesis of Chiral 1,3-Disubstituted Tetrahydroisoquinolines and Their Use in the Asymmetric Addition of Diethylzinc to Aldehydes
Patricia D. MacLeod, Amy M. Reckling, and Chao-Jun Li*
*Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, Quebec H3A 2K6, Canada
Abstract
The effects of modification on three sites of 1-(1,2,3,4-tetrahydro-isoquinolin-1-yl)-naphthalen-2-ol (THIQNOL) chiral ligands on the asymmetric diethylzinc additions were examined. The studies showed that modifications at the nitrogen only reduces the efficiency of these types of ligands, whereas modification at the 3-position of the 1,2,3,4-tetrahydroisoquinoline ring and the 3-position of the naphthol ring can lead to chiral ligands which provide better enantioselectivities. In general, the use of a simple phenyl group on the 1,2,3,4-tetrahydroisoquinoline ring and either a phenyl or methoxyphenyl on the naphthol ring generates more effective chiral ligands for the asymmetric addition of diethylzinc to aldehydes.
Published online: 14th October, 2009
■ 2-Substituted Isotellurochromenium Salt Derivatives: Preparations, Structures, Spectroscopic Properties
Haruki Sashida,* Shoko Nakabayashi, Mamoru Kaname, and Mao Minoura
*Faculty of Pharmaceutical Sciences, Hokuriku University, 3-Ho, Kanagawa machi, Kanazawa 920-1181, Japan
Abstract
Several types of novel isotellurochromenium salt derivatives (2-10) were prepared from the isotellurochromenes (1). The isotellurochromenium tetrafluoroborates (2), triflates (3-5), tosylates (6) and mesylates (7) are telluronium salts, and the dihalogenoisotellurochromenes (8-10) are telluranes. The molecular structures of the isotellurochromenium tosylate (6a) and the dichloroisotellurochromene (8a) were characterized by an X-ray crystallographic analysis using the 3-tert-butyl derivatives.
Published online: 3rd December, 2009
■ Efficient Preparation of Urocanic Acid Derivatives from Histidine
Carl J. Lovely,* Rasapalli Sivappa, Sabuj Mukherjee, Thomas Doundoulakis, Heather M. Lima, and Muhammed Yousufuddin
*Department of Chemistry, The University of Texas at Arlington, 502 Yates Street, Arlington, TX 76019, U.S.A.
Abstract
Urocanic acid derivatives have served as useful starting materials in several total synthesis endeavors in our lab. This paper describes a convenient, large-scale synthesis of several derivatives of urocanic acid via the net elimination of ammonia from histidine.
Published online: 5th October, 2009
■ Synthetic Studies Connected with the Preparation of N-[3-(3-Cyanopyrazolo[1,5-a]pyrimidin-5-yl)phenyl]-N-ethylacetamide, a Zaleplon Regioisomer
Stanislav Rádl,* Michaela Blahovcová, Marcela Tkadlecová, and Jaroslav Havlíček
*Organic Synthesis, Zentiva, U Kabelovny 130, 102 01 Prague 10, Czech Republic
Abstract
N-[3-(3-Cyanopyrazolo[1,5-a]pyrimidin-5-yl)phenyl]-N-ethylacetamide, a principal impurity of zaleplon, is prepared by Suzuki-Miyaura cross coupling reaction of the corresponding boronic acid and/or boronates with 5-chloropyrazolo[1,5-a]pyrimidin-3-carbonitrile (7). Various methods of preparation of both components are described, as well as approaches based on the final modification of the 5-(3-aminophenyl)-pyrazolo[1,5-a]pyrimidine-3-carbonitrile moiety prepared by Suzuki-Miyaura cross coupling. All the prepared compounds were unambiguouesly identified by NMR techniques. Spectral characteristics (IR, UV, MS) of these compounds are also given.
Published online: 26th October, 2009
■ Application of Samarium Diiodide-Promoted Reductive Carbon-Nitrogen Bond Cleavage Reaction to 3-Oxopyrrolidine Derivatives: Alternative Synthesis of a Coccinellid Alkaloid, (-)-Adalinine
Toshio Honda* and Chihiro Hisa
*Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
Abstract
Samarium diiodide-promoted reductive deamination reaction was applied to 5,5-disubstitued 3-oxopyrrolidines to provide 4,4-disubstituted 4-aminobutan-2-one derivatives, where the carbon-nitrogen bond cleavage took place at the desired position, regioselectively. This strategy was exploited in the synthesis of a coccinellid alkaloid, (-)-adalinine.
Published online: 4th November, 2009
■ Platisidines A-C, N-Methylpyridinium Alkaloids from an Okinawan Marine Sponge of Plakortis Species
Takaaki Kubota, Yuichiro Ishiguro, Sunao Yamamoto, Jane Fromont, and Jun'ichi Kobayashi*
*Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
Three new N-methyl pyridinium alkaloids, platisidines A-C (1-3), were isolated from an Okinawan marine sponge of the genus Plakortis, and the structures were elucidated from spectroscopic data. The structures of platisidines A-C (1-3) were elucidated to be N-methyl nicotinic acid derivatives with a n-hexadecanoyl chain. Platisidines A-C (1-3) showed inhibitory activity against acetylcholinesterase.
Published online: 10th November, 2009
■ Heteroaromatic Trapping of Tricyclic 2-Oxidocyclopentenyl Cations: A Surprisingly Efficient Example of Intermolecular Interrupted Nazarov Reaction
Curtis J. Rieder, Ryan J. Fradette, and Frederick G. West*
*Gunning/Lemieux Chemistry Center, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
Abstract
Bis(cycloalkenyl) ketones 2a and 2f underwent Nazarov cyclization and intermolecular trapping by electrophilic aromatic substitution with furans, thiophenes, pyrroles, indoles and dimethoxybenzene. Only the cis-anti-cis diastereomer was isolated with dicyclopentenyl ketone 2a, whereas a mixture of diastereomers was seen with 2f (albeit with complete regioselectivity). Comparable interrupted Nazarov trapping was not seen with acyclic dienones 2b-e, indicating the possible involvement of conformation effects in the polycyclic intermediates derived from 2a and 2f.