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. 2, 2008
Published online: 22nd May, 2008
■ A Convenient Synthesis of Fluorine-Containing Dihydrobenzo[b][1,4]diazepinols and Its Application to a Synthesis of Novel N-Sulfinylanilines
Norio Ota, Takehisa Tomoda, Naoya Terai, Yasuhiro Kamitori,* Dai Shibata, Maurice Médebielle, and Etsuji Okada*
*Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
The reactions of 1,1,1,5,5,5-hexafluoro-3-(isobutoxymethylene)-pentane-2,4-dione (1) with various benzene-1,2-diamines gave 2,5-dihydro-3-trifluoroacetyl-2-trifluoromethyl-1H-benzo[b][1,4]diazepines (5) in moderate to high yields under very mild conditions. Also, 2,5-dihydro-3-perhaloalkanoyl-2-perhaloalkyl-1H-benzo[b][1,4]diazepines (7) were synthesized successfully by quite similar manner. Reactions of thus obtained dihydrobenzo[b][1,4]diazepinols (5) with thionyl chloride gave unexpected novel fluorine-containing N-sulfinylanilines (9).
Published online: 2nd June, 2008
■ Synthesis, Structure, and Cholinergic Effect of Novel Neuroprotective Compounds Bearing the Tacrine Pharmacophore
Slávka Hamul’aková, Pavol Kristian,* Daniel Jun, Kamil Kuca, Ján Imrich, Ivan Danihel, Stanislav Böhm, and Karel D. Klika
*Institute of Chemistry, Faculty of Science, P. J. Safárik University, SK-041 67 Kosice, Slovak Republic
Abstract
Novel tacrine congeners with side ligands suitable for optimal interaction with the peripheral and catalytic sites of acetyl- and butyrylcholinesterase (AChE and BuChE) have been synthesized using either 9-isothiocyanato-1,2,3,4-tetrahyhroacridine or 9-chloro-1,2,3,4-tetrahydroacridi- ne which represent convenient synthons by reaction with various substituted amines. The synthesized compounds were tested for their inhibition of AChE and BuChE whereby a morpholine and a furfuryl derivative were found to be the most potent AChE and BuChE inhibitors, respectively, with the latter compound comparable in activity to tacrine.
Published online: 22nd May, 2008
■ Synthesis of 1’,2’,3’,4’,5’-Pentamethyl-3,4-diphenylazaferrocene and Its Enantioselective C-2 Functionalization via (-)-Sparteine-Mediated Lithiation
Tsutomu Fukuda, Yasuyuki Koga, and Masatomo Iwao*
*Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
Lithiation of 1’,2’,3’,4’,5’-pentamethyl-3,4-diphenylazaferrocene (9) with sec-BuLi/(-)-sparteine (2) in Et2O at -78 °C followed by quenching with electrophiles gave the C-2 functionalized azaferrocenes (17) in good enantioselectivities (up to 79% ee). In contrast, treatment of 9 with tert-BuLi/(-)-sparteine (2) leaded to lateral lithiation at the methyl group of cyclopentadienyl ring.
Published online: 19th May, 2008
■ Selective Halogen Dance Reactions at 5,5’-Dibromo-2,2’-bithiophene
Roman Bobrovsky, Christian Hametner, Wolfram Kalt, and Johannes Fröhlich*
*Vienna University of Technology, Institute of Applied Synthetic Chemistry,
Getreidemarkt 9/163, 1060 Vienna, Austria
Abstract
Selective single and double halogen migrations were achieved at 5,5’-dibromo-2,2’-bithiophene by varying the amount of lithiation reagent, and a number of tri- and tetrasubstituted bithiophenes was obtained by quenching the lithio intermediates with various electrophiles. Some of the mono-rearranged products were subjected to a second migration in order to introduce two different substituents. Finally, the potential of the resulting compounds to undergo lithium¬induced ring opening reactions was demonstrated on a few examples.
Published online: 26th May, 2008
■ Rhodium-Catalyzed Intramolecular Cycloaddition of Cyclopropene-ynes Triggered by Carbon-Carbon Bond Cleavage
Takanori Shibata,* Shunsuke Maekawa, and Kohei Tamura
*Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo, 169-8555, Japan
Abstract
In the presence of a catalytic amount of RhCl(PPh3)3, an intramolecular cycloaddition of cyclopropene-yne proceeded along with carbon-carbon bond cleavage of cyclopropene ring to give various bicyclic cyclopentadiene derivatives in good to high yield.
Published online: 26th May, 2008
■ Iridium Catalyzed Enantioselective Hydrogenation of N-Iminopyridinium Ylides: Mechanistic Insights
Claude Y. Legault, André B. Charette,* and Pier G. Cozzi
*Département de Chimie, Université de Montréal, P.O. Box 6128, Station Downtown, Montréal, Québec, H3C 3J7, Canada
Abstract
Mechanistic insights of the efficient iridium catalyzed asymmetric hydrogenation of N-iminopyridinium ylides are reported. Using NMR and mass spectrometry, the nature of the pre-catalyst and role of iodine was studied. The effect of solvent as well as an extensive ligand screening is presented. Deuteration experiments also show that C-H(D) insertion pathways occur in competition with the hydrogenation process.
Published online: 22nd May, 2008
■ Asymmetric Hetero Diels-Alder Reaction of Nitroso Compounds Utilizing Tartaric Acid Ester as a Chiral Auxiliary
Hiroki Sakai, Xia Ding, Tetsusuke Yoshida, Shuhei Fujinami, Yutaka Ukaji,* and Katsuhiko Inomata*
*Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
Abstract
The regio- and enantioselective hetero Diels-Alder reaction of a nitroso compound with a cyclic dienol, cyclohexa-1,3-dienylmethanol, has been realized utilizing stoichiometric amount of tartaric acid ester as a chiral auxiliary to afford the corresponding dihydro-1,2-oxazine with complete regioselectivity and high enantioselectivity of up to 92% ee. A catalytic version of the asymmetric hetero Diels-Alder reaction of nitroso compounds with the dienol was also achieved to afford the corresponding optically active cycloadducts with up to 83% ee. The addition of MS 4A was crucial to realize reproducible high enantioselectivity.
Published online: 19th May, 2008
■ Development of Column-Free Alkoxycarbonyl, Aryloxycarbonyl, and Acyl Transfer Reagents
Mamoru Shimizu and Mikiko Sodeoka*
*Synthetic Organic Chemistry Laboratory, RIKEN (The Institute of Physical and Chemical Research), 2-1, Hirosawa, Wako, 351-0198, Japan
Abstract
Easy-to-handle alkoxycarbonyl, aryloxycarbonyl, and acyl transfer reagents, which contain 3-nitro-1,2,4-triazole (NT) as a leaving group, were developed. With these reagents (NT reagents), which are stable nonhygroscopic crystalline materials, the reactions can be accomplished in about 5 min, and product can be isolated without tedious column chromatographic purification.
Published online: 19th May, 2008
■ 2,6-Dimethyl-4-nitrobenzoic Anhydride (DMNBA): An Effective Coupling Reagent for the Synthesis of Carboxylic Esters and Lactones
Isamu Shiina* and Ryo Miyao
*Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 Japan
Abstract
Various carboxylic esters are obtained at room temperature in excellent yields with high chemoselectivities from nearly equimolar amounts of carboxylic acids and alcohols using 2,6-dimethyl-4-nitrobenzoic anhydride with triethylamine by the promotion of 4-(dimethylamino)pyridine. The efficiency of the esterification is compared to those of other dehydrations using substituted benzoic anhydrides as coupling reagents. This method was successfully applied to the synthesis of threo-aleuritic acid lactone and the desired 17-membered ring compound was prepared in high yield at room temperature from the corresponding free trihydroxycarboxylic acid using 2,6-dimethyl-4-nitrobenzoic anhydride in the presence of 4-(dimethylamino)pyridine.
Published online: 2nd June, 2008
■ A Convenient Synthesis of Optically Active Biopterin
Yuichi Shiro, Fumi Urano, Yasuhiro Kuroda, and Shizuaki Murata*
*Graduate School of Environmental Studies, Nagoya University, Chikusa, Nagoya, 464-8601 Japan
Abstract
Naturally occurring L-erythro-biopterin is synthesized using regioselective pteridine-ring formation from the chiral α,β-epoxyaldehyde intermediate which is prepared from ethyl L-lactate via Sharpless epoxidation.
Published online: 19th May, 2008
■ Synthesis of 2’-Deoxy-4’-C-hydroxymethyl-4’-thioribonucleosides and Their 2’,3’-Dideoxy and 2’,3’-Didehydro-2’,3’-dideoxy Analogues
Junzo Nokami,* Masayuki Mae, Satoshi Fukutake, Tomoyuki Ubuka, and Mitsuhiro Yamada
*Department of Applied Chemistry, Faculty of Engineering, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan
Abstract
(±)-2’-Deoxy-4’-C-hydroxymethyl-4’-thioribonucleosides (1) and their 2’,3’-dideoxy- (2) and 2’,3’-didehydro-2’,3’-dideoxy- (3) analogues have been prepared from hydrothiophene derivatives 2,2-bis(benzyloxymethyl)-3-benzyloxytetrahydrothiophene (4), 2,2-bis(acetoxymethyl)tetrahydrothiophene (5) and 2,2-bis(acetoxymethyl)-2,5-dihydrothiophene (6), respectively. Preparation of the compound 1 has been carried out via N-glycosylation of the corresponding sulfoxide 9, derived from 4 by m-CPBA oxidation, with trimethylsilylated pyrimidines and trimethylsilyl triflate (Kita-O’Niel-Matsuda’s method; modified Pummerer rearrangement). On the other hand, the compounds 2 and 3 have been obtained via N-glycosylation of the corresponding 4’-thiofuranoses 7 and 8 with trimethylsilylated pyrimidines and SnCl4, respectively, while the compounds 7 and 8 have been prepared from compounds 5 and 6 by an electrochemical 2-acetoxylation, respectively.
Published online: 5th June, 2008
■ Influence of the Position of tert-Butyl Substituents on Reactivity of Quinone Dimers Yielding Dibenzofuran-1,4-diones
Naoto Hayashi,* Akifumi Kanda, Hiroyuki Higuchi, and Keiko Ninomiya
*Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama 930-8555, Japan
Abstract
Reactivity of two isomeric quinone dimers, 5,5’-di-tert-butyl-2,2’-bisbenzoquinone (2) and 6,6’-di-tert-butyl-2,2’-bisbenzoquinone (3) have been compared. Both quinone dimers underwent thermal cyclization in ethanol to give dibenzofuran-1,4-diones exclusively, the reaction proceeding faster for 3 than for 2. Molecular modeling analysis indicates that the different reactivity should be explained in terms of the steric hindrance of tert-butyl group in 2, which prevents approaching of solvent molecules to C=O moiety so that the solvent-assisted proton transfer occurs more slowly.
Published online: 7th July, 2008
■ The MCD Spectroscopy of Corrolazines and Triazatetrabenzocorroles
John Mack, Masaru Bunya, David Lansky, David P. Goldberg,* and Nagao Kobayashi*
*Department of Chemistry, Faculty of Graduate Science, Tohoku University, Sendai 980-8578, Japan
Abstract
We report the first MCD spectral data for free base corrolazine and a transition metal corrolazine complex. A detailed analysis of the MCD and UV-visible absorption spectroscopy of these compounds and phosphorous corrolazine and triazatetrabenzocorroles is carried out based on the results of TD-DFT calculations and an application of Michl’s perimeter model.
Published online: 26th May, 2008
■ Diastereoselective Nucleophilic Cyclopropanation of 1,2-Diketones and α-Ketoimines with Bis(iodozincio)methane
Kenichi Nomura, Keisuke Asano, Takuya Kurahashi, and Seijiro Matsubara*
*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoutodaigaku-katsura, Nishikyo-ku, Kyoto 615-8510, Japan
Abstract
A reaction of 1,2-diketones and α-ketoimines with bis(iodozincio)methane gave cyclopropan-1,2-diol and 2-aminocyclopropanol respectively via nucleophilic [2+1]cycloaddition. The reaction proceeded via a sequential nucleophilic attack of the dizinc reagent to vicinal two carbonyl group. The reaction showed high diastereoselectivity to give cis-isomer via a face-to-face coordination between the substrate and bis(iodozincio)methane.
Published online: 26th June, 2008
■ Triphenylphosphoranylidene Substituted Heterocycles as Versatile Intermediates
Alan R. Katritzky,* Adam S. Vincek, and Peter J. Steel
*Center for Heterocyclic Compounds, University of Florida, Department of Chemistry, Gainesville, Florida 32611-7200, USA
Abstract
N-Cbz-(α-aminoacyl)benzotriazoles 5a-e reacted with (stabilized-methylene)triphenylphosphoranes 6 and 13 to give the corresponding esters 7a-e (66-91%) or nitriles 14a-e (63-85%). Deprotection of N-Cbz-γ-amino-β-oxo-α-triphenylphosphoranylidene esters 7a-d induced cyclization to form 2,4-dioxo-3-triphenylphosphoranylidene pyrrolidines 9a-c (20-98%) and 1,3-dioxo-2-triphenylphosphoranylidene tetrahydropyrrolizine 9d (79%). N-Cbz-δ-amino-β-oxo-α-triphenylphosphoranylidene ester 7e cyclized to form 2,4-dioxo-3-triphenylphosphoranylidene piperidine 9e (60%). Deprotection of N-Cbz-γ-amino-β-oxo-α-triphenylphosphoranylidene nitriles 14a-d similarly formed 5-amino-4-triphenylphosphonio-2,4-dihydropyrrol-3-one bromides 15a-c (70-72%) and 3-ammonio-2-triphenylphosphoniotetrahydro- pyrrolizin-1-one dibromide 15d (66%). N-Methyl pyrrolidine 11 was transformed into 3,3-dibromopyrrolidin-2,4-dione 16 (79%), 3,3-dibromo-5- hydroxypyrrolidin-2,4-dione 17 (88%), 4-azido-3-bromopyrrol-2-one 18 (84%), and 4-benzotriazol-1-ylpyrrol-2-one 19 (92%).
Published online: 19th June, 2008
■ Synthesis and Evaluation of Isomers of Melleumin B from the Myxomycete Physarum melleum; an Approach for Wnt Signal Inhibitor Trusted in Nature
Midori A. Arai, Yujiro Uchino, Shuwa Hanazawa, Xiaofan Li, Naoki Kimura, and Masami Ishibashi*
*Graduate School of Pharmaceutical Science, Chiba University, Chiba 263-8522, Japan
Abstract
Two stereoisomers of melleumin B (1), seco acid methyl ester of melleumin A (2), which are novel peptide compounds isolated from the myxomycete Physarum melleum, were synthesized and evaluated for their inhibition of Wnt signal transcription. The 3R-epimer and (3R, 4S, 10R, 11R)-isomer of 1 showed moderate inhibition of the Wnt signal.
Published online: 26th June, 2008
■ Novel Substituted Tetrathia[7]helicenes by Direct Functionalization of the Helical System or Photocyclization of Substituted 1,2-(Bis-benzodithienyl)ethenes
Clara Rigamonti, Maria Teresa Ticozzelli, Alberto Bossi, Emanuela Licandro,* Clelia Giannini, and Stefano Maiorana*
*Department of Organic and Industrial Chemistry, University of Milan, via Venezian, 21 I-20133 Milan, Italy
Abstract
In this work we report the synthesis of several new tetrathia[7]helicenes ([7]THs) functionalized with different electron-donor (ED) and electron-acceptor (EA) substituents in the positions 2,13 (the α positions of terminal thiophene rings) and/or 7,8 (on the central arene ring of the helical system). Some substituents were chosen on the basis of theoretical calculations performed on [7]THs to predict the best groups for applications in optoelectronics; some others were conceived to endow helicenes with appropriate groups in view of their insertion into polymeric structures.
Published online: 19th June, 2008
■ Electrooxidative Desulfurization/Chlorination. A Facile Synthesis of 4-Chloro-2-azetidinones, a Potent Intermediate for Carbapenems
Manabu Kuroboshi, Masayoshi Miyada, Syoichi Tateyama, and Hideo Tanaka*
*Department of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530, Japan
Abstract
(3S,4R)-3-(1’(R)-tert-Butyldimethylsilyloxyethyl)-4-chloro-2-azetidinone (2), a potent intermediate for the synthesis of carbapenem antibiotics, was synthesized by thermal ring opening/acylation of (3S,5R,6S)-6-(1’(R)-tert-butyldimethylsilyloxyethyl)penicillanate S-oxide (8) leading to 4-acylthio-2-azetidinone derivative 9 and subsequent removal of the N-substituent followed by electrooxidative desulfurization/chlorination of the C(4)-acylthio moiety.
Published online: 30th June, 2008
■ Construction of Chiral Quaternary Carbon Centers via Palladium-Catalyzed Asymmetric Deconjugative Allylation
Hiroki Yamamoto, Yoshihiro Oonishi, and Yoshihiro Sato*
*Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
Abstract
A Pd(0)-catalyzed asymmetric deconjugative allylation of various Knoevenagel products and allylic compounds was investigated. It was found that various compounds, having a quaternary carbon center directly attached to sp2-carbon centers including a 1,3-diene moiety, could be synthesized through this methodology, although the yield and enantiomeric excess varied from low to modest depending on the structure of substrates and the reaction conditions.
Published online: 12th June, 2008
■ Synthesis of Tetrahydroisoquinoline Antitumor Natural Products: Construction of Tricyclic Lactams Through Pictet-Spengler-Type Cyclization of N-Methyl-3-arylmethylpiperazine-2,5-dione with Ethyl Diethoxyacetate
Masashi Yokoya, Osamu Kawachi, and Naoki Saito*
*Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
Abstract
6-Hydroxymethyl-7,8,10-trimethoxy-2,6-dimethyl-3,6,11,11a-tetrahydro-2H-pyrazino[1,2-b]isoquinoline-1,4-dione (10) was prepared stereoselectively by Pictet-Spengler-type cyclization of the N,O-acetal of 3-arylmethylpiperazine-2,5-dione (8) in high yield. This procedure provides an efficient route for the total synthesis of renieramycin G and cribrostatin 4.
Published online: 7th August, 2008
■ Synthesis of Substituted Aziridines via Intramolecular Reaction of β-N-Chloroethylamino Carbanions
Mieczyslaw Makosza,* Karolina Bobryk, and Dariusz Krajewski
*Institute of Organic Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland
Abstract
Simple and efficient method of synthesis of 2-alkoxycarbonyl, 2-cyano, 2-phenylsulfonyl N-alkylaziridines was elaborated via intramolecular nucleophiles substitution of chloride in 1-N-chloro-2-alkoxycarbonyl (cyano, phenylsulfonyl) ethyl amines. These substituted N-chloroamines are readily erasable via N-chlorination of the adducts of primary amines to Michael acceptors.
Published online: 28th July, 2008
■ Benzophenone-Derived Catalyst with Self-Adaptation: Highly Enantioselective Hydrogenation Irrespective of Ketone Substrates
Kazuki Wakabayashi, Kohsuke Aikawa, and Koichi Mikami*
*Department of Applied Chemistry, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
Abstract
The Ru complex with the tropos benzophenone-derived diphosphine ligand could be chirally controlled to a single chiral conformation instantaneously with a chiral diamine to attain high enantioselectivity in the asymmetric hydrogenation irrespective of ketone substrates. In the asymmetric hydrogenation of not only 1-acetonaphthone but also 9-acetylanthracene, the tropos Ru complex fits well with the substrate change to give high catalytic activity and enantioselectivity upon addition of silver salts such as AgOTf.
Published online: 23rd June, 2008
■ Enantioselective Synthesis of Both Enantiomers of Etodolac via a Lipase-Catalyzed Kinetic Resolution
Shuji Akai,* Hiroyuki Nemoto, and Masahiro Egi
*School of Pharmaceutical Sciences, University of Shizuoka 52-1, Yada, Suruga-ku, Shizuoka, Shizuoka 422-8526, Japan
Abstract
The efficient preparation of both enantiomers of etodolac 1 was achieved by the lipase-catalyzed kinetic resolution of the racemic primary alcohol (±)-2 followed by chemoselective oxidation.
Published online: 5th June, 2008
■ De Novo Asymmetric Approaches to 2-Amino-N-(benzyloxycarbonyl)-1-(2’-furyl)ethanol and 2-Amino-N-(tert-butoxycarbonyl)-1-(2’-furyl)ethanol
Michael H. Haukaas, Miaosheng Li, Alexey M. Starosotnikov, and George A. O’Doherty*
*Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA
Abstract
Several methods were investigated for the de novo asymmetric synthesis of 2-amino-N-(benzyloxycarbonyl)-1-(2’-furyl)ethanol and 2-amino-N-(tert-butoxycarbonyl)-1-(2’-furyl)ethanol. A five step procedure was developed for the practical preparation of optically pure 2-amino-N-(benzyloxycarbonyl)-1-(2’-furyl)ethanol and a shorter 2-step procedure was developed for 2-amino-N-(tert-butoxycarbonyl)-1-(2’-furyl)ethanol. Both routes used a Noyori reduction to install the asymmetry.
Published online: 7th July, 2008
■ Inhibition of NF-Kappa B Activation by Penicillic Acid and Dihydropenicillic Acid Isolated from Fungi
Miyuki Tachibana, Chino Matsui, Yoshinori Takeuchi, Eriko Suzuki, and Kazuo Umezawa*
*Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-0061, Japan
Abstract
In the course of our screening of NF-κB inhibitors from microbial secondary metabolites, we isolated two 2(5H)-furanones, penicillic acid and dihydropenicillic acid, from the culture filtrate of Penicillium. Both penicillic acids inhibited LPS-induced NO production and NF-κB activation. They did not inhibit protein synthesis. Interestingly, penicillic acid inhibited advanced glycation end product (AGE)-induced NO production.
Published online: 26th June, 2008
■ Xestosaprol C, a New Pentacyclic Hydroquinone Sulfate from a Marine Sponge Xestospongia sapra
Takaaki Kubota, Yuji Kon, and Jun’ichi Kobayashi*
*Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
Abstract
A new pentacyclic hydroquinone sulfate with a 2,5-dihydro-2,5-furandiol ring, xestosaprol C (1), has been isolated from an Okinawan marine sponge Xestospongia sapra. The structure of 1 was elucidated by the spectroscopic data.
Published online: 19th June, 2008
■ Free Radical Tandem Addition-Cyclization of Te-Phenyl N,N-Dimethylcarbamotelluroate to 1,6-Enynes
Shin-ichi Fujiwara,* Yoshihiko Shimizu, Yoshimasa Makita, Tsutomu Shin-ike, and Nobuaki Kambe*
*Department of Chemistry, Osaka Dental University, Hirakata, Osaka 573-1121, Japan
Abstract
Free radical tandem addition of Te-phenyl N,N-dimethyl- carbamotelluroate (1) to alkenes and alkynes was examined. Simple addition of carbamotelluroate 1 to alkenes such as styrene and methyl acrylate did not take place under irradiation of visible light. However, when alkynes were added to this system, photo-induced three-component radical coupling proceeded to give alkenyl tellurides 6 in moderate yields. This reaction could be applied to heterocycles synthesis by use of 1,6-dienes 7. Carbamotelluroate 1 added to allyl propargyl ethers or an amine 7 under light giving rise to tetrahydrofuran or pyrrolidine 8 by tandem radical addition/cyclization reaction.
Published online: 7th July, 2008
■ The NCN-Type Pincer Complex of Palladium(II) with a 2,6-Bis(2-pyridyl)-4-tert-butylbenzene Tridentate Ligand: Synthesis, Structure and Catalytic Activity in the Mizoroki-Heck Reaction
Yuichi Hirano, Yuji Saiki, Hideki Taji, Shiro Matsukawa, and Yohsuke Yamamoto*
*Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
Abstract
The reaction of 1-bromo-4-tert-butyl-2,6-diiodobenzene with 2-pyridylzinc chloride in the presence of catalytic Pd(PPh3)4 afforded an NCN-type pincer palladium(II) complex with two pyridine donors. The structure of the complex was determined by X-ray crystallography. The complex was found to catalyze the Mizoroki-Heck reaction at 250 °C under aerobic conditions.
Published online: 7th August, 2008
■ Asymmetric Dieckmann Condensation via Memory of Chirality: Synthesis of the Key Intermediate for AS-3201, an Aldose Reductase Inhibitor
Toshihide Watanabe and Takeo Kawabata*
*Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
Abstract
Asymmetric Dieckmann condensation via memory of chirality has been developed. A key intermediate for the synthesis of AS-3201, an aldose reductase inhibitor, has been prepared in 94% ee by asymmetric Dieckmann condensation of 8 derived from L-aspartic acid.
Published online: 16th June, 2008
■ Synthesis of Oriented Anti-Virus 7-O-Substituted Apigenins
Kin-ichi Oyama, Tadao Kondo, and Kumi Yoshida*
*Graduate School of Inforamtion Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan
Abstract
7-O-Substituted apigenins were synthesized for searching anti-virus active compound. Using a commercially available naringenin as a starting material, 7-O-methylapigenin (1) and seven unnatural 7-O-substituted apigenin derivatives (13-19) were prepared via 4’-O-methoxymethylapigenin (5) as an intermediate.