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. 1, 2010
Published online: 17th March, 2009
■ M10709, a New Cyclic Peptide Antibiotic from Clinically Isolated Streptomyces sp.
Takuya Kumamoto, Hiroyuki Koshino, Daisuke Watanabe, Yuko Matsumoto, Kazuki Aoyama, Ken-ichi Harada, Tsutomu Ishikawa, and Yuzuru Mikami*
*Chiba University, , Japan
Abstract
A new cyclic heptapeptide, M10709, was isolated from the mycelial cake of a clinically isolated Streptomyces sp. IFM 10709. The planar structure of M10709 was determined on the basis of IR, MS, NMR, and UV spectra. The absolute configuration of α-position of amino acid residues in the acid hydrolysate was determined by advanced Marfey’s method to be L except that of tryptophan-derived amino acid. The compound showed antibacterial activity against Micrococcus luteus IFM 2066.
Published online: 1st April, 2009
■ Regioselective Synthesis of 2,4-(Dioxobutyl)dihydroquinolines and -pyridines by Chloroformiate-Mediated Reaction of 1,3-Bis(Silyl Enol Ethers) with Quinolines and Pyridines
Uwe Albrecht, Anja Preuss, Andreas Schmidt, Christine Fischer, and Peter Langer*
*Institute of Chemistry, University of Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany
Abstract
2,4-(Dioxobutyl)dihydroquinolines and –pyridines were prepared by chloroformiate-mediated reaction of 1,3-bis(silyl enol ethers) with quinolines and pyridines.
Published online: 23rd April, 2009
■ Characterization of Various O-Bisguanidinobenzene-Benzoic Acid Complexes in Solid and in Solution States
Takuya Kumamoto, Kazuaki Shikii, Masatoshi Kawahata, Kentaro Yamaguchi, Waka Nakanishi, Tsutomu Ishikawa, and Hiroko Seki*
*Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
Abstract
Stoichiometry-controlled complexation of o-phenylenebis(N,N’-dimethyl-N,N’-ethylene)guanidine (BG) and benzoic acid (BA), which is forming 1 : n (n = 1 – 4) BG + BA systems, was observed in the solid state by X-ray structure analysis and in solution by using cold-spray ionization mass spectrometry (CSI-MS) and pulsed field gradient (PFG)-NMR diffusion. The relation of observed diffusion coefficient in solution phase and the volume of the corresponding complexes estimated by calculation of the solid state structure showed good linearity, which implies that the volume of the complexes would increase depend on the ratio of BA to BG.
Published online: 13th April, 2009
■ Total Synthesis of (+)-Cacospongionolide B
Motoko Oshida, Misaki Ono, Atsuo Nakazaki, and Susumu Kobayashi*
*Faculty of Pharmaceutical Sciences, Science University of Tokyo, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
Abstract
Total synthesis of (+)-cacospongionolide B was achieved. The synthesis involved highly stereoselective C-glycosidation of a glycal derived from D-arabinose with 3-furyl boronic acid in the presence of a palladium catalyst and B-alkyl Suzuki–Miyaura coupling of in situ generated alkylborane prepared by the reaction of vinyl trans-decalin with alkenyl triflate.
Published online: 14th May, 2009
■ Hetero Diels-Alder Reaction of β-Trifluoroacetylated Vinyl Ethers with Vinyl Ethers to Access Fluorine-Containing Dihydropyran Derivatives — A Molecular Orbital Calculation Study
Norio Ota, Yasuhiro Kamitori,* Dai Shibata, and Etsuji Okada*
*Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
The reactivity differences between β-trifluoroacetylvinyl ethers (1), β,β-bis(trifluoroacetyl)vinyl ethers (2), β-acetylvinyl ethers (3), and β,β-diacetylvinyl ethers (4) in the hetero Diels-Alder reaction with vinyl ethers giving dihydropyrans (5, 6, 7, and 8, respectively) are discussed on the basis of molecular orbital calculations. Frontier orbital interactions and activation energies of these reactions were estimated using DFT calculations.
Published online: 8th June, 2009
■ Bumaldosides A, B and C from the Leaves of Staphylea bumalda
Hideaki Otsuka,* Qian Yu, and Katsuyoshi Matsunami
*Divison of Medicinal Chemisry, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
Abstract
Two new aliphatic diglycosides and a phenolic glucoside (4, 5 and 7) have been isolated from leaves of Staphylea bumalda DC., together with three known compounds, benzyl and phenethyl alcohol glycosides (1 and 2), and zingerone β-D-glucopyranoside (6). 2-Ethyl-3-methylmaleimide N-glucopyranoside (3) was first isolated as a free form. Their structures were determined on the basis of spectroscopic analysis.
Published online: 15th June, 2009
■ Regioselective Synthesis of Trifluoromethyl Group Substituted Pyrazole Derivatives from 1-Aryl-3,4,4,4-tetrafluoro-2-buten-1-ones
Keisuke Sano and Shoji Hara*
*Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0828, Japan
Abstract
Trifluoromethyl group substituted pyrazole derivatives were prepared from hydrazines and 1-aryl-3,4,4,4-tetrafluoro-2-buten-1-ones obtained by the deoxyfluorination of β-diketones. The reaction proceeded regioselectively and 5-aryl-3-trifluoromethyl-1-phenyl-1H-pyrazole was obtained from phenylhydrazine. On the other hand, when methylhydrazine was used, 3-aryl-5-trifluoromethyl-1-methyl-1H-pyrazole was selectively formed.
Published online: 14th July, 2009
■ Palladium-Catalyzed Cross-Coupling Reaction of Heteroaryltriolborates with Aryl Halides for Synthesis of Biaryls
Yasunori Yamamoto,* Miho Takizawa, Xiao-Qiang Yu, and Norio Miyaura*
*Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0828, Japan
Abstract
Cyclic triolborates possessing a heteroaromatic ring on the boron atom [ArB(OCH2)3CHCH3]M (M=K, Na, Li) were prepared in high yields from heteroarylboronic acids, 1,1,1-tris(hydroxymethyl)ethane (triol) and KOH or NaH. The corresponding lithium salts were synthesized from aryllithiums, B(OMe)3 and triol. They were air-stable white solids that were convenient for handling in air. High performance of these triolborates for metal-catalyzed bond-forming reactions was demonstrated in palladium-catalyzed cross-coupling reactions with haloarenes. Although the use of heteroarylboronic acids often results in very low yields due to competitive hydrolytic B-C bond cleavage with water under typical conditions using aqueous bases, triolborates possessing a 2-pyridyl, 3-pyridyl or 2-thiophenyl ring afforded biaryls in high yields at 50-120 ˚C in anhydrous DMF. There was a strong accelerating effect of CuI for reactions of 2- and 3-pyridylborate derivatives, whereas 2-thiophenyl derivatives reacted smoothly resulting in high yields in the absence of CuI.
Published online: 7th August, 2009
■ Synthesis of 3-Aryl-1,2-dicarba-closo-dodecaboranes by Suzuki-Miyaura Coupling Reaction
Koei Aizawa, Kiminori Ohta, and Yasuyuki Endo*
*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
Abstract
In contrast to conventional syntheses of 3-aryl-o-carborane derivatives, which involve reconstruction of the o-carborane cage or Pd-catalyzed coupling reaction of 3-iodo-o-carborane with Grignard reagents, the Suzuzki-Miyaura coupling reaction of 3-iodo-o-carborane proceeds with a variety of aryl boronic acids, providing a new route to 3-aryl-o-carborane derivatives bearing easily transformable functional groups, including CH3O-, NO2-, CHO- and CN-. This approach provides easy access to a variety of compounds with a 3-aryl-o-carborane scaffold.
Published online: 5th August, 2009
■ Chemo- and Regioselective Imino Diels-Alder Reactions: Synthesis of Functionalized Novel Quinolin-3-one and Quinoline Derivatives
Chander Mohan, Gaurav Bhargava, and Mohinder P. Mahajan*
*Department of Applied Chemistry, Guru Nanak Dev University, Amritsar 143 005, Punjab, India
Abstract
Regio- and catalyst selective imino Diels-Alder reactions of vinyl/isopropenyl pyrimidinones with N-arylimines in the presence of metal salts viz. magnesium(II) bromide, zinc(II) chloride, indium(III) chloride, yttrium triflate and scandium triflate, are described. An unprecedented oxidation of methylene to carbonyl has been shown to accompany the imino Diels–Alder reactions of isopropenyl pyrimidinones in the presence of yttrium and scandium triflates. Chemoselective effect of different Lewis acids used as catalysts in these reactions has been rationalized.
Published online: 14th July, 2009
■ Synthesis of (+)-Batzelladine K
Miyuki Sekine, Yumi Iijima, Osamu Iwamoto, and Kazuo Nagasawa*
*Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588, Japan
Abstract
Total synthesis of batzelladine K (1), a marine guanidine alkaloid, was achieved based upon successive 1,3-dipolar cycloaddition reaction of cyclic nitrone. The relative and absolute stereochemistry of 1 was established by spectral comparison of the natural and synthetic products and the trans-isomer, which was also synthesized.
Published online: 11th August, 2009
■ Selective Triisopropylsilylation of α-Amino Acids: Protection without Racemization
Buddy Soto-Cairoli, Iveliz Kock, Jorge Justo de Pomar, Guang Yang, José M. Guzmán, Javier R. González, Augie Antomattei, and John A. Soderquist*
*Department of Chemistry, University of Puerto Rico, San Juan, PR 00931-3346, U.S.A.
Abstract
The mono-, di- and trisilylation of α-amino acids with TIPSOTf is described. Treatment of the α-amino acids, proline and tryptophan with TIPSOTf in MeCN provides a quantitative yield of the corresponding ammonium salts of the O-TIPS esters (4). Employing two (2) equivalents of TIPSOTf/EDIPA produces N,O-bis-TIPS amino acid derivatives (2) without racemization as stable compounds (73–87%, 13 examples). Three (3) equivalents of this silylation mixture produces the corresponding tris-TIPS derivatives 6 (62–88%, 6 examples) from amino acids which contain protic functionality in their side chain. While this trisilylation procedure is ineffective for tryptophan, the N,O-bis-TIPS derivative 2m is easily prepared through this method, and the third silylation is achieved without racemization employing t-BuLi/R3SiX producing N1-SiR3-N,O-bis-TIPS tryptophans (51–97%, 4 examples).
Published online: 29th July, 2009
■ Synthesis and Some Reactions of 11-Azacyclohept[a]azulen-3(3H)-ones and Evaluation of Their Cytotoxic Activity against HeLa S3 Cells
Tomoyuki Ariyoshi, Kengo Yoshinaga, Kazuya Koizumi, Hiroyuki Fujii, Reiko Ikeda, Takeo Konakahara, and Noritaka Abe*
*Graduate School of Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan
Abstract
Aldol condensation of 2,3-diformyl-1-azaazulene with acetone, methoxyacetone, and benzylacetone in aq. NaOH solution gave corresponding 11-azacyclohept[a]azulen-3(3H)-one (2a), 2-methoxy-derivative (2b) and 2-benzyl-derivative (2d) in good yields. Hydrolysis of 2b using hot HBr gave 2-hydroxy-11-azacyclohept[a]azulen-3(3H)-one (2f). Acetylation of 2f gave 2-acetoxy-11-azacyclohept[a]azulen-3(3H)-one (2g). Reaction of the compounds (2a, 2b, 2f) with diethyl malonate in Ac2O under heating gave 1,9(11bH)-11b-azaazuleno[1,2,3-cd]azulenedione derivatives (4a, 4b, 4f). Compounds (2b, 2f) showed weak cytotoxic activity against HeLa S3 cells.
Published online: 18th August, 2009
■ A New Approach to Imidazo[1,2-a]pyridine Derivatives and Their Application to the Syntheses of Novel 2H-Pyrano[2’,3’:4,5]imidazo[1,2-a]pyridin-2-one Derivatives
Takashi Abe, Yukihisa Okumura, Hiroyuki Suga, and Akikazu Kakehi*
*Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
Abstract
3-[Bis(methylthio)methylene]-2(3H)-imidazo[1,2-a]pyridinones were prepared from the S-alkylation of pyridinium 1-[1-carbamoyl-1-[(methylthio) thiocarbonyl]]methylides with methyl iodide followed by the alkaline treatment of the resulting pyridinium salts. The reactions of these 3-methylene-2(3H)-imidazo[1,2-a]pyridinones with some ethyl cyano- or acyl-substituted acetates in the presence of a base did not afford the initially expected 2H-pyrano[2’,3’:4,5]imidazo[1,2-a]pyridine-2-one derivatives, but, instead of them, provided ethyl 3-[2-hydroxyimidazo[1,2-a]pyridin-3-yl]acrylates. The thermolyses of these acrylates without any solvent under reduced pressure gave the corresponding 2H-pyrano[2’,3’:4,5]imidazo[1,2-a]pyridine-2-one derivatives.
Published online: 24th July, 2009
■ Chemical Confirmation of the Structure of a Mutagenic Aminophenylnorharman, 9-(4’-Aminophenyl)-9H-pyrido[3,4-b]indole: An Authentic Synthesis of 9-(4’-Nitrophenyl)-9H-pyrido[3,4-b]indole as Its Relay Compound
Yasuoki Murakami,* Nobuyuki Imai, Tsuyoshi Miura, Takashi Sugimura, Keiji Wakabayashi, Yukari Totsuka, Noriyasu Hada, Yuusaku Yokoyama, Hideharu Suzuki, and Katsuyoshi Mitsunaga
*Faculty of Pharmaceutical Sciences, Chiba Institute of Science, 15-8 Shiomi-cho, Choshi, Chiba 288-0025, Japan
Abstract
9-(4’-Aminophenyl)-9H-pyrido[3,4-b]indole 2 is a mutagenic compound produced by non-mutagenic norharman 1 and aniline in the presence of S9 mix. 9-(4’-Nitrophenyl)-9H-pyrido[3,4-b]indole 4, the relay compound for synthesis of 2, was synthesized starting from ethyl indole-2-aldehyde 12 via initial N-(4-nitro)phenylation of the indole nucleus, elongation of the 2-aldehyde substituent, and then construction of the pyridine nucleus in order to ensure the nitrogen substitution in 2.
Published online: 11th August, 2009
■ New Monomeric and Dimeric Hydrolyzable Tannins from Tamarix nilotica
Mohamed A. A. Orabi, Shoko Taniguchi, Morio Yoshimura, Takashi Yoshida, and Tsutomu Hatano*
*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan
Abstract
Two new ellagitannin monomers, nilotinins M2 (4) and M3 (5), two new dimers, nilotinins D4 (6), D5 (7), and a known dimer (8), were isolated from an aqueous acetone extract of dried leaves of Tamarix nilotica (Ehrenb.) Bunge. Structures of 4–7 were determined based on spectral data and chemical correlations with known tannins. The known dimer 8 was isolated from a plant extract for the first time; its 1H and 13C assignments are also reported here.
Published online: 31st August, 2009
■ Glycosides from Vallaris solanaceae with TRAIL-Resistance-Overcoming Activity
Firoj Ahmed, Samir Kumar Sadhu, Takashi Ohtsuki, Amina Khatun, and Masami Ishibashi*
*Graduate School of Pharmaceutical Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
Abstract
A new cardenolide glycoside, vallarisoside (1), and a known one, 3β-O-(α-acofriosyl)-16-anhydrogitoxigenin (2) along with a new glycoside, benzyl 2-O-β-apiofuranosyl-(1→2)-β-D-glucopyranosyl-2, 6-dihydroxy-benzoate (3) were isolated from Vallaris solanaceae. Structures of the isolates were elucidated by 1D and 2D NMR and mass spectroscopic analysis. Of the isolates, vallarisoside (1) showed potent TRAIL-resistance-overcoming activity in human gastric adenocarcinoma (AGS) cells and cell-growth-inhibitory activity against HeLa and SW480 cells.
Published online: 1st September, 2009
■ Selective Formation of 5- or 6-Membered Rings, 1,3-Thiazolidin-4-one vs. 1,3-Thiazin-4-one, from Acridine Thiosemicarbazides by the Use of Ethyne Acid Esters
Ján Imrich,* Jana Tomaščiková, Ivan Danihel, Pavol Kristian, Stanislav Böhm, and Karel D. Klika
*Institute of Chemistry, Faculty of Science, P. J. Šafárik University, Moyzesova 11, SK-041 67 Košice, Slovak Republic
Abstract
A set of 2-substituted 1-(9,10-dihydroacridin-9-ylidene) thiosemicarbazides 4a-d (H, methyl, ethyl, and n-butyl substituents) were treated with dimethyl acetylenedicarboxylate (DMAD) to yield 5-membered ring 1,3-thiazolidin-4-one products 5a-d. The methyl derivative 4b, upon reaction with methyl propiolate (MP), yielded a 6-membered thiazin-4-one ring product 7b. The structures of the methyl derivative products 5b and 7b were conclusively proven by NMR examinations and compared to X-ray crystallographic analysis. The ring−chain tautomerism of the thiosemicarbazides, the regio- and stereoselectivity of the reactions, the adopted s-cis conformations of the Z configurations of the products, and the prototropic tautomerism of all the compounds were all substantiated.
Published online: 20th August, 2009
■ A Self-Supported Palladium-Bipyridyl Catalyst for the Suzuki-Miyaura Coupling in Water
Takao Osako and Yasuhiro Uozumi*
*Laboratory of Complex Catalysis, Institute for Molecular Science, Myodaiji, Okazaki 444-8787, Japan
Abstract
A self-supported palladium catalyst (PdCl2BPy–Cu) was prepared via construction of a metal-organic framework (MOF) of a bipyridyl-palladium complex bearing carboxylic groups and a copper(II) linker. PdCl2BPy–Cu efficiently catalyzed the Suzuki-Miyaura coupling of phenyl halides with arylboronic acids in water under atmospheric conditions to afford the corresponding biaryl products in high yield. The catalyst was reused four times without loss of catalytic activity.
Published online: 1st September, 2009
■ A Facile Synthesis of 4-Aryl-1,1,1-trifluorobut-3-en-2-ones via 4-Aryl Substituted CF3 - Containing Dihydropyran Derivatives: A Versatile Method for the Introduction of Fluorine-Containing C4- and C6-Unit to Aromatic Compounds
Norio Ota, Etsuji Okada,* Dai Shibata, Satoru Adachi, and Shohei Saikawa
*Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
The CF3 - containing dihydropyran derivative (2) reacted easily with various aromatic compounds in trifluoroacetic acid to give novel 4-aryl substituted dihydropyran derivatives (7) in moderate to high yields. Retro hetero Diels-Alder reaction of thus obtained 7 proceeded readily by heating at 300 °C to afford the corresponding 4-aryl-1,1,1-trifluorobut-3-en-2-ones (12) in good to excellent yields. With the use of p-toluenesulfonic acid instead of trifluoroacetic acid together with dihydropyran (2) in acetonitrile, 4-trifluoroacetyl-1,3-butadienylation of 1,3-dimethoxybenzene occurred successfully. The bimolecular reaction of dihydropyran (2) in the presence of p-toluenesulfonic acid was also examined.
Published online: 1st September, 2009
■ Preparation and Ferroelectric Properties of New Chiral Liquid Crystalline Organic Radical Compounds
Naohiko Ikuma, Katsuaki Suzuki, Yoshiaki Uchida, Rui Tamura,* Yoshio Aoki, and Hiroyuki Nohira
*Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
Abstract
We have synthesized new chiral liquid crystalline (LC) organic radical compounds 2 and 3, which are the derivatives of the previously reported compounds 1 containing a chiral cyclic nitroxide unit and an ester group in the mesogen core, and their ferroelectric properties have been studied. The enantiomerically enriched (2S,5S)-2 and (2S,5S)-3 showed an SmC* phase for which their ferroelectric properties such as spontaneous polarization (Ps) and tilt angle (θ) were compared with those of (2S,5S)-1.
Published online: 2nd September, 2009
■ C–C Bond Formation on 5-Position of Uridine Ring by Morita–Baylis–Hillman Type Reaction
Yasunari Monguchi, Kanoko Yasunaga, Takashi Tsunoda, Takayuki Ando, Tomohiro Maegawa, Kosaku Hirota, and Hironao Sajiki*
*Laboratory of Medicinal Chemistry, Gifu Pharmaceutical University, 6-1 Mitahora-higashi 5-chome, Gifu 502-8585, Japan
Abstract
A useful and efficient C–C bond formation reaction at the 5-position of uridine derivatives using a wide range of aldehydes was established on the basis of the Morita–Baylis–Hillman type reaction.
Published online: 26th August, 2009
■ Novel and Facil Synthesis and Evaluation of Antitumor Activities of 6,7-Bisaryl-1-(β-D-ribofuranosyl)pteridine-2,4(1H,3H)-diones
Rafiya Khan Kandahary, Abugafar M. L. Hossion, Noriyuki Ashida, and Tomohisa Nagamatsu*
*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan
Abstract
Novel 6,7-bisaryl-1-(β-D-ribofuranosyl)pteridine-2,4(1H,3H)-dione derivatives were synthesized by condensation of 5,6-diamino-2’,3’-O-iso-propylideneuridine, which was derived from uridine, with an appropriate α,β-diketone, followed by acidic hydrolysis allowing removal of the isopropylidene group of the sugar moiety as a protecting group. Moreover, several N-3 alkyl derivatives of the 6,7-bisaryl-1-(β-D-ribofuranosyl)pteridine-2,4(1H,3H)-diones were obtained by alkylation of the 6,7-bisaryl-1-(2’,3’-O-isopropylidene-β-D-ribofuranosyl)pteridine-2,4(1H,3H)-diones with alkyl halides and by their acidic hydrolysis for deprotection. The antitumor activities of all synthesized compounds against CCRF-HSB-2 and KB cell lines were also investigated in vitro and some of the compounds showed prospective antitumor activities.
Published online: 26th August, 2009
■ Synthesis of Macrosphelides Containing a Heterocyclic Side Chain as a Novel Apoptosis Inducer
Yuji Matsuya,* Ayana Hori, Tomomi Kawamura, Heba F. Emam, Kanwal Ahmed, Da-Yong Yu, Takashi Kondo, Naoki Toyooka, and Hideo Nemoto
*Faculty of Pharmaceutical Sciences, Toyama University, 2630 Sugitani, Toyama, Toyama 930-0194, Japan
Abstract
Synthesis of macrosphelides containing a pyridyl or benzimidazolyl side chain is described. The synthesis was accomplished through sequential assembling of suitable chiral blocks and ring-closing metathesis (RCM) with a high efficiency. These novel derivatives were evaluated on the apoptosis-inducing activity against human lymphoma cells.
Published online: 21st April, 2009
■ Nickel–Promoted Favorskii Type Rearrangement of Cyclic α-Bromoketones
Vishnu K. Tandon,* Anoop K. Awasthi, Kunwar A. Singh, Hardesh K. Maurya, and Sanjay K. Gautam
*Department of Chemistry, University of Lucknow, Lucknow, U.P. 226007, India
Abstract
Favorskii type rearrangement of cyclic α-bromo ketones 2 is promoted by NiCl2 in refluxing methanol, giving the rearranged carboxylic acid ester 3 in excellent yields. The reaction of 4-bromo-2,3,4,5-tetrahydronaphth [2,1-b]oxepin-5-one (5) and its regioisomer 8 with NiCl2 in MeOH resulted in Favorskii rearranged carboxylic acid esters 6 and 9 respectively.
Published online: 1st July, 2009
■ The Selective Deiodination of Iodoheterocycles Using the PhSiH3 – In(OAc)3 System
Osamu Sugimoto,* Minami Sugiyama, and Ken-ichi Tanji*
*Laboratory of Organic Chemistry, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
Abstract
Nitrogen-containing π-deficient heterocyclic iodides such as iodoquinolines or iodopyridines were deiodinated by treatment with phenylsilane catalyzed by indium acetate to give the corresponding deiodinated heterocycles at ambient temperature.
Published online: 15th May, 2009
■ A New Diterpenoid Alkaloid, Sharwuphinine A from Delphinium sharwurense
Chen Li, Yusuke Hirasawa, Hiroko Arai, Haji Akber Aisa,* and Hiroshi Morita*
*Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
Abstract
A new diterpenoid alkaloid, sharwuphinine A (1) was isolated from the aerial part of Delphinium sharwurense and the structure possessing a lycoctonine-type C19-diterpenoid alkaloid with a nitrone functionality was elucidated by spectroscopic analysis. Sharwuphinine A (1) showed moderate vasorelaxant activity on rat aorta.
Published online: 26th June, 2009
■ Biyouxanthones A - D, Prenylated Xanthones from Roots of Hypericum chinense
Naonobu Tanaka, Takuji Mamemura, Shuhei Abe, Kiyoshi Imabayashi, Yoshiki Kashiwada, Yoshihisa Takaishi, Tetsuro Suzuki, Yutaka Takebe, Takaaki Kubota, and Jun'ichi Kobayashi*
*Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
Four new prenylated xanthones, biyouxanthones A – D (1 – 4), were isolated from roots of Hypericum chinense. The gross structures of 1 – 4 were elucidated from spectroscopic data, and 2 was assigned as a racemate by chiral HPLC analysis. Biyouxanthones A (1) and B (2) exhibited anti-viral activity against hepatitis C virus (HCV).
Published online: 6th July, 2009
■ A Synthetic Study on Bauhinoxepin J: Construction of a Dibenzo[b,f]oxepin Ring System by a DDQ-Promoted Oxidative Dearomatization–Cyclization Approach
Masahiro Yoshida,* Yohei Maeyama, and Kozo Shishido
*Graduate of School of Pharmaceutical Sciences, University of Tokushima, 1-78-1 Sho-machi, Tokushima 770-8505, Japan
Abstract
Efforts to construct a dibenzo[b,f]oxepin ring system for a synthesis of bauhinoxepin J are described. A DDQ-promoted oxidative dearomatization–cyclization of the 2-phenoxyethyl-substituted tetramethoxybenzene was used to construct a tricyclic quinone monoacetal.
Published online: 4th August, 2009
■ Titanium Tetraisopropoxide Promoted Reactions for the Synthesis of Substituted Coumarins
Takanori Tanaka, Kohei Yamashita, and Masahiko Hayashi*
*Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
Substituted coumarins are synthesized by the reaction of salicylaldehyde derivatives with malonitrile, isopropyl cyanoacetate or diisopropyl malonate promoted by Ti(O-i-Pr)4. When i-PrOH is used as a solvent, these reactions proceeded by the catalytic amount of Ti(O-i-Pr)4 (~0.1 equivalent).