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. 1, 2012
Published online: 13th July, 2012
■ Asymmetric Syntheses of Pyrrolidine and Piperidine Derivatives via Regio- and Stereo-Selective Ring-Opening Reactions of Chiral Aziridine
Kimio Higashiyama,* Masataka Matsumura, Emiko Kurita, and Takayasu Yamauchi
*Institute of Medicinal Chemistry, Hoshi University, Ebara 2-4-41, Shinagawa-ku, Tokyo 142-8501, Japan
Abstract
Asymmetric synthesis of cyclic β-amino alcohols (pyrrolidine and piperidine derivatives) has been achieved using a single chiral aziridine as the starting material. The key step of this synthetic methodology is regio- and stereo-controlled ring-opening of the chiral aziridine with acetic acid or acetyl chloride.
Published online: 24th July, 2012
■ Isolation of Ellagitannin Monomer and Macrocyclic Dimer from Castanopsis carlesii Leaves
Yong-Lin Huang, Takashi Tanaka,* Yosuke Matsuo, Isao Kouno, Dian-Peng Li, and Gen-ichiro Nonaka
*Department of Natural Product Chemistry, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
In a phytochemical and chemotaxonomical investigation of Castanopsis species (Fagaceae), new monomeric and dimeric ellagitannins, named carlesiins A (1) and B (2), were isolated from fresh leaves of Castanopsis carlesii along with 55 known compounds. Carlesiin A was identified as 1-O-galloyl-4,6-(S)-tergalloyl-β-D-glucose. Carlesiin B is a macrocyclic ellagitannin dimer with a symmetrical structure composed of two tergalloyl and two glucopyranose moieties. Their structures were elucidated based on spectroscopic and chemical evidence.
Published online: 27th July, 2012
■ Side-Chain Lithiation of 2- and 4-Substituted Pyridines: Synthesis of More Complex Substituted Pyridines
Keith Smith,* Gamal A. El-Hiti,* Ahmed Fekri, and Mohammed B. Alshammari
*School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, U.K.
Abstract
Lithiation of pyridines substituted in the 2- and 4-positions by acylaminomethyl groups, namely of the corresponding N-(pyridinylmethyl)pivalamides, N' -(pyridinylmethyl)-N,N-dimethylureas and tert-butyl N-pyridinylmethylcarbamates, with two mole equivalents of t BuLi in anhydrous THF at 78 °C takes place on the nitrogen and on the methylene group of the side-chain. The lithium reagents thus obtained react with a variety of electrophiles to give the corresponding side-chain substituted derivatives in high yields.
Published online: 8th August, 2012
■ Highly Stereoselective Synthesis of anti-Tetrahydropyrimidine Derivatives under Microwave Heating
Qian Wang, An-Xiao Dai, Mian-Shuai Yi, Bo Jiang, Shu-Jiang Tu,* and Guigen Li*
*Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, U.S.A.
Abstract
New [3+3] heterocyclization has been established for the synthesis of anti-tetrahydropyrimidine derivatives. The reaction was conducted by reacting readily available and inexpensive starting materials, such as 4-arylidene-2-phenyloxazol-5(4H)-ones, and aryl amidines, under solvent-free condition and microwave irradiation. During the reaction processes, the selective construction of anti-tetrahydropyrimidine skeleton and two amide functions were readily achieved via TEA-catalyzed ring-opening of oxazoles in a one-pot operation; in the meanwhile, lactone was converted into corresponding lactam in an intermolecular manner.
Published online: 7th August, 2012
■ SYNTHESIS AND BIOLOGICAL EVALUATION OF A NOVEL ACRONYCINE/DUOCARMYCIN HYBRID NATURAL PRODUCT
Lutz F. Tietze,* Arne Heins, Johannes R. Reiner, Svenia-C. Duefert, and Ingrid Schuberth
*Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstr. 2, D-37077 Göttingen, Germany
Abstract
he design of novel natural product hybrids consisting of parts of two or more bioactive compounds may allow an access to new drugs. Here we describe a hybrid of the cytotoxic acronycine (2) and seco-duocarmycin 3, which was prepared via a selective bromination of 7 followed by the introduction of an alkyne moiety, which was further manipulated to give the epoxide 12. Cyclisation and chlorination of the formed primary hydroxy group yielded 3, which in situ would give the desired hybrid 4. The in vitro cytotoxicity test revealed a slightly higher bioactivity than acronycine (2).
Published online: 27th July, 2012
■ Nucleophilic Substitution Reaction of 1-Methoxyindole-3-carbaldehyde
Fumio Yamada, Daisuke Shinmyo, Masahiro Nakajou, and Masanori Somei*
*Noto Marine Laboratory, Institute of Nature and Environmental Technology, Faculty of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, 56-7 Matsuhidai, Matsudo-shi, Chiba 270-2214, Japan
Abstract
1-Methoxyindole-3-carbaldehyde is proved to be a versatile electrophile and reacts regioselectively at the 2-position with various types of nucleophiles providing 2-substituted indole-3-carbaldehydes.
Published online: 24th July, 2012
■ Selective Deprotection of Methylene Acetal and MOM Ether in the Presence of Ketal-Type Protective Groups: Remarkable Effect of TBSOTf
Tomohiro Maegawa, Yasuyuki Koutani, Kento Senami, Kenzo Yahata, and Hiromichi Fujioka*
*Graduate School of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 560-0871, Japan
Abstract
A novel procedure for highly selective deprotection of methylene acetals and MOM (methoxymethyl) groups in the presence of ketal-type protective groups has been developed. The method, which utilizes a combination of TBSOTf and 2,2’-bipyridyl, displays a completely opposite selectivity compared with those of acid-mediated deprotection protocols.
Published online: 31st July, 2012
■ Catalytic Asymmetric Synthesis of (S)-Laudanosine by Hydroamination
Tokutaro Ogata, Tetsutaro Kimachi, Ken-ichi Yamada, Yasutomo Yamamoto, and Kiyoshi Tomioka*
*Department of Medicinal Chemistry, Doshisha Women’s College of Liberal Arts, Kodo, Kyotanabe, Kyoto 610-0395, Japan
Abstract
Lithium amide–chiral bisoxazoline-catalyzed asymmetric intramolecular hydroamination was examined with respect to the structural variants of starting aminoalkenes. Substituents on the nitrogen and olefin of aminoalkenes were found to be important factors affecting reaction efficiency as well as enentioselectivity in the production of chiral tetrahydroisoquinolines and isoindolines. The catalytic asymmetric total synthesis of (S)-laudanosine highlights the utility of the asymmetric hydroamination.
Published online: 3rd August, 2012
■ SYNTHESIS OF PHENANTHRIDINES AND RELATED COMPOUNDS BY PALLADIUM-CATALYZED DIRECT COUPLING VIA C–H AND N–H BOND CLEAVAGES
Daisuke Takeda, Koji Hirano, Tetsuya Satoh,* and Masahiro Miura*
*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
Abstract
The palladium-catalyzed direct annulation of benzophenone imines with o-dihalobenzenes proceeds through C–H and N–H bond cleavages to produce 6-arylphenanthridine derivatives. 2-Phenyl-imidazole, -benzimidazole, and -indole also undergo the annulation to form the corresponding tetra- and pentacyclic compounds.
Published online: 31st July, 2012
■ THREE NEW BISABOLANE-TYPE SESQUITERPENOIDS FROM CREMANTHODIUM rHODOCEPHALUM (ASTERACEAE)
Yoshinori Saito, Koji Takiguchi, Xun Gong, Chiaki Kuroda, and Motoo Tori*
*Faculty of Pharmaceutical Sciences, Tokushima Bunri University, 180 Nishihamabouji, Yamashiro-machi, Tokushima, 770-8514, Japan
Abstract
From Cremanthodium rhodocephalum (Asteraceae) collected in Yunnan Province of China, four bisabolane-type (three of them were new) and one oplopane-type sesquiterpenoid were isolated. Two new hydroperoxides were the first example with the bisabolane-type skeleton. This is the first report about the study on C. rhodocephalum.
Published online: 13th August, 2012
■ SHORT APPROACH TO BISINDOLE ALKALOID, YUEHCHUKENE, USING 2-INDOLYLCYANOCUPRATE
Takumi Abe, Hiroyuki Komatsu, Toshiaki Ikeda, Noriyuki Hatae, Eiko Toyota, and Minoru Ishikura*
*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
Abstract
A short total synthesis of a bisindole alkaloid, yuechukene, was achieved through the dimerization of β-dehydroprenylindole generated in situ from 1-(indol-3yl)-3-methylbut-2-en-1-amine.
Published online: 2nd August, 2012
■ SYNTHESIS OF BIS-nAPHTHOPORPHYRINS
Hiroki Uoyama, Hiroko Yamada, Tetsuo Okujima, and Hidemitsu Uno*
*Department of Chemistry and Biology, Graduate School or Science and Engineering, Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan
Abstract
Ethanonaphthoporphyrins with a halogen atom at the ζ position were prepared by the [3+1] porphyrin synthesis of halogen-substituted ethanobenz[f]isoindole with a tripyrrane derivative. The halogeno porphyrins were converted to the corresponding ethynyl and pinacolatoboronyl compounds by Sonogashira and borylation reactions, respectively. Suzuki, Sonogashira, and Glaser coupling reactions of these ethanonaphthoporphyrins gave bis-porphyrins connected with no atom, acetylene, and butadiyne, respectively. Retro Diels-Alder reaction of these bis-porphyrins brought about the conversion of bicyclo[2.2.2]octadiene to benzene moieties to give bis-naphthoporphyrins, quantitatively.
Published online: 31st July, 2012
■ Synthesis of 15,28-Dideoxy-15,28-didehydrothyrsenol
Mary A. Smart and Frank E. McDonald*
*Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322, U.S.A.
Abstract
The tetracyclic skeleton of thyrsenols A and B has been assembled, with the construction of ring A by exo-selective oxacyclization of an epoxybromohydrin, B ring formation by exo-selective oxacyclization of hydroxyepoxide followed by solvolytic ring expansion of a tetrahydrofuran to tetrahydropyran, C ring closure by tungsten-promoted endo-selective oxacyclization of a hydroxyalkyne, and D ring preparation by asymmetric dihydroxylation of an epoxyalkene accompanied by exo-selective oxacyclization. A modified Stille coupling linked two fragments at C14-C15 to directly provide the tetracyclic dienylether.
Published online: 8th August, 2012
■ N-Chlorosuccinimide/Sodium Hydroxide-Mediated Synthesis of Benzimidazoles from Amidines under Mild Conditions
Thanh Binh Nguyen,* Ludmila Ermolenko, and Ali Al-Mourabit
*Department of Chemistry, Institut de Chimie des Substances Naturelles, CNRS, 1, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France
Abstract
A convenient room-temperature one-pot procedure for the preparation of benzimidazoles derivatives from N-arylamidines has been developed. The reaction of N-aryl-N'-chloro amidines, generated by the treatment of N-aryl amidines with N-chlorosuccinimide, in presence of sodium hydroxide provides benzimidazoles in good to excellent yields. Nitrogen anion generated in situ from succinimide (by-product of the chlorination step using NCS) and hydroxide anion was found to be highly effective as Brønsted base to promote the cyclization into benzimidazole of N-aryl-N'-chloroamidine.
Published online: 6th August, 2012
■ ASSEMBLY OF THE SOUTHERN MACROCYCLIC HALF OF (+)-SPIRASTRELLOLIDE A THROUGH CYCLIC ACETAL TETHERED RING-CLOSING METATHESIS AND 1,3-ANTI-MUKAIYAMA-ALDOL
Yu Tang,* Jin-Haek Yang, Jia Liu, Chao-Chao Wang, Ming-Can Lv, Yi-Biao Wu, Xue-Liang Yu, Changhong Ko, and Richard Hsung*
*Department of Chemistry, School of Pharmacy, University of Wisconsin, 777 Highland Aenue, Madison, WI 53705, U.S.A.
Abstract
We describe herein details of our efforts in syntheses of A-ring and BC-ring of (+)-spirastrellolide A. While the former would constitute a facile 12-step synthetic endeavor starting from 1,5-pentanediol, the latter would showcase a cyclic acetal-tethered ring-closing metathesis [RCM] method that was developed in our lab for de novo synthesis of spiroketals. Constructing the entire Southern Half of the macrocycle would require 1,3-anti-Mukaiyama aldol addition for connecting A-ring and BC-ring specifically at C10 and C11, thereby culminating a 17-step approach for the C1-23 fragment linearly from (+)-2,3-(O)-iso-propylidene-L-threitol. Also discussed here is the possibility of pursuing a more convergent approach toward the assembly of the Southern Half through first connecting A-ring and C-ring via acetal formation that would first link together the free C13-OH with C17 at the spiro-BC-ring junction. An ensuing application of our cyclic acetal-tethered RCM strategy to close B-ring would adopt this cyclic acetal intermediate.
Published online: 19th July, 2012
■ Platinum-Catalyzed Regioselective Hydration of 1-(2-Propynyl)-2-formylpyrroles
Masahiro Yoshida* and Shota Yodokawa
*Graduate of School of Pharmaceutical Sciences, University of Tokushima, 1-78-1 Sho-machi, Tokushima 770-8505, Japan
Abstract
The hydration reaction of 1-(2-propynyl)-2-formylpyrroles with a platinum catalyst in aqueous media is described. Various 1-(2-oxopropyl)-2-formylpyrroles were regioselectively synthesized via the platinum-promoted intramolecular 6-exo-dig cyclization pathway.
Published online: 30th July, 2012
■ Direct Catalytic Asymmetric Vinylogous Michael Reaction of α,β-Unsaturated γ-Butyrolactam under Dinuclear Nickel Schiff Base Catalysis
Hirooki Tanabe, Yingjie Xu, Bo Sun, Shigeki Matsunaga,* and Masakatsu Shibasaki*
*Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Abstract
Direct catalytic asymmetric vinylogous Michael reaction is described. 2.5 mol % of homobimetallic (S)-Ni2-Schiff base complex efficiently catalyzed the addition of α,β-unsaturated γ-butyrolactam to nitroalkenes under simple proton transfer conditions, giving vinylogous Michael products in 83-99% yield, 16:1->30:1 dr, and 96-99% ee.
Published online: 13th August, 2012
■ Novel Efficient Synthesis and Properties of 5,6-Dihydrocyclohepta[b]indol-6-one, and Its Transformation to 6-Azolyl-5-azabenz[b]azulenes
Mitsunori Oda,* Kunihiro Ito, Hiroshi Takagi, and Yurie Fujiwara
*Department of Chemistry, Faculty of Science, Shinshu University, Asahi, Matsumoto 390-8621, Japan
Abstract
The title compound, 5,6-dihydrocyclohepta[b]indol-6-one (1), was synthesized from 2-chlorotropone (7) by a two-step sequence involving Pd-catalyzed amination with 2-bromoaniline (15) and subsequent Pd-catalyzed intramolecular Heck reaction. Besides its synthetic detail, some physical properties of 1, such as acidity, basicity and spectroscopic behavior, were also reported. Compound 1 was transformed into 6-(1H-pyrazol-1-yl)- and 6-(1H-1,2,3-triazol-1-yl)-5-azabenz[b]azulenes (13 and 14) as a potential ligand.
Published online: 7th August, 2012
■ SYNTHESIS AND PROPERTIES OF AZULENE-SUBSTITUTED THIOPHENES, TERTHIOPHENES AND DITHIENOTHIOPHENES
Tetsuo Okujima,* Akiko Toda, Yoko Miyashita, Ayumi Nonoshita, Hiroko Yamada, Noboru Ono, and Hidemitsu Uno
*Department of Chemistry and Biology, Graduate School or Science and Engineering, Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan
Abstract
Bis(azulenylethynyl)thiophenes, terthiophenes, and dithienothiophenes have been synthesized by the Pd-catalyzed cross-coupling of the corresponding diiodothiophenes with 1- and 6-ethynylazulenes under Sonogashira–Hagihara conditions.
Published online: 30th July, 2012
■ STEREOSELECTIVE SYNTHESIS OF 2-SUBSTITUTED 1-IODO-1,3-dIENES BY THE ADDITION OF MeMgSnBu3 TO THE CONJUGATED TERMINAL ENYNES; STEREOCONTROLLED SYNTHESIS OF (2E,4Z,6E)-DEHYDRODENDROLASIN
Reiko Kawahama and Jun'ichi Uenishi*
*Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan
Abstract
Addition of MeMgSnBu3 to the conjugated enynes 1 and 5 were thoroughly studied. The addition reactions were proceeded stereoselectively at –20 °C, but a thermal isomerization occurred when the reaction was carried out at 0 °C. (2E,4Z,6E)-Dehydrodendrolasin 14 was synthesized using the isomerized 2-methyl-1-iodo-1,3-diene product 17.
Published online: 30th May, 2012
■ Synthetic Studies on α,α-Disubstituted Amino Acids Employing (2S,4R)-4-Hydroxyproline as the Chiral Pool: Preparation of Methyl O-Benzyl-2-(α-cyanomethyl)-D-tyrosinate and Dimethyl 2-(4-hydroxybenzyl)-L-aspartate
Ryohei Nagahara, Chihiro Hisa, Noriko Kojima, Naoshi Yamamoto, and Toshio Honda*
*Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
Abstract
Methyl O-benzyl-2-(α-cyanomethyl)-D-tyrosinate and dimethyl 2-(4-hydroxybenzyl)-L-aspartate were synthesized starting from (2S,4R)-4-hydroxyproline via Beckmann fragmentation of the corresponding oxime tosylate.
Published online: 25th May, 2012
■ Enantioselective Mukaiyama-Aldol Reaction between Enol Silanes and Ketomalonate Catalyzed by the Copper(II) Complex of TIPS-Substituted Bis-oxazoline
Giovanni Desimoni,* Guiseppe Faita, Alessandro Livieri, and Laura Ponta
*Department of Chemistry, University of Pavia, Viale Teramelli 10, I-27100 Pavia, Italy
Abstract
The stable complex [(4'S,5'S)-4b/Cu(Tf)2/H2O] (5), obtained from TIPS-Box and Copper triflate, catalyzes enantioselectively the Mukaiyama-aldol reactions between two silyl enol ethers (1a,b) and diethyl ketomalonate (2). Yields are very good and the ee of (R)-3b is up to 94%. When the reaction was catalyzed by 4-Ph-Box complex [(4'R)-4a/Cu(Tf)2], in which the configuration at the C-4 centre is opposite to that of 5, the same enantiomer was obtained. The undistorted square pyramidal structure of complex 5, determined by crystallographic structure, and the effect of water and molecular sieves on efficiency and selectivity of the catalyst, suggest some proposals to rationalize the resulting stereoselectivity.
Published online: 13th August, 2012
■ α-SUBSTITUTED UNSYMMETRICAL PHTHALOCYANINES WITH ONE THROUGH THREE TTF UNITS AND THEIR OPTICAL AND ELECTROCHEMICAL PROPERTIES
Takeshi Kimura,* Nobuhiro Takahashi, Tomoyuki Tajima, and Yutaka Takaguchi
*Center for Instrumental Analysis, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan
Abstract
α-Substituted unsymmetrical phthalocyanines fused with one through three TTF units were prepared on treatment of mixed 3,6-dioctyltetrathia- fulvalenophthalonitrile and 3,6-dioctoxyphthalonitrile with lithium alkoxide at 120 °C. The optical and electrochemical properties of the products were determined by UV-vis spectroscopy and cyclic voltammetry.
Published online: 17th July, 2012
■ A C2-Symmetric Pool Based Synthesis of the Furanoside of Hygromycin A
Hong-Jay Lo, Yuan-Kang Chang, Feng-Yi Lin, and Tu-Hsin Yan*
*Department of Chemistry, National Chung Hsing University, 250, Kuo Kuang Road, Taichung 40227, Taiwan, R.O.C.
Abstract
The readily available and inexpensive D-tartaric acid serves as the chiral building block for synthesis of the furanoside of hygromycin A. Key to our successes in the asymmetric synthesis of the furanose segment was the melding of several key reactions, such as the successful application of the monosilylation of C2-symmetric diol, diastereocontrolled di(2-propenyl)zinc addition to the aldehyde, and TMSCl-MeOH promoted desilylation, acetal-cleavage, and intramolecular esterification in one-step.
Published online: 29th June, 2012
■ A CONVENIENT SYNTHESIS OF THE L-LIKE ENANTIOMER OF 4'-METHYL-3-dEAZAARISTEROMYCIN
Chun Chen, Wei Ye, and Stewart W. Schneller*
*Department of Chemistry and Biochemistry, Auburn University, 179 Chemistry Building, Auburn, AL 36849-5312, U.S.A.
Abstract
As an entry into L-like 3-deazaaristeromycins, synthesis of the enantiomer of D-like 4'-methyl-3-deazaaristeromycin is described in 11 steps from a readily accessible cyclopentenone that, in turn, is prepared from D-ribose.
Published online: 13th August, 2012
■ COMPUTATIONAL STUDY ON ACID CATALYZED RING-OPENING REACTION OF 2,4-DIETHOXY-6-TRIFLUOROMETHYL-3,4-DIHYDRO-2H-PYRAN WITH THIOLS
Norio Ota, Yasuhiro Kamitori,* Mizuki Hatakenaka, 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
2,4-Diethoxy-6-trifluoromethyl-3,4-dihydro-2H-pyran was reacted with thiols in the presence of p-toluenesulfonic acid by heating followed by treatment with trifluoroacetic acid to afford the corresponding 4-trifluoroacetyl-1,3-butadienyl sulfides selectively. Our DFT calculation results suggest thermodynamically controlled attack of thiols at 6-position of pyrylium intermediate followed by electrocyclic ring-opening as a reasonable mechanism for this reaction.
Published online: 31st July, 2012
■ IMIDAZOLE AND IMIDAZOLINE DERIVATIVES AS N-DONOR LIGANDS FOR NICKEL-CATALYZED KUMADA-TAMAO-CORRIU COUPLING
Ryo Iwamoto and Masahiko Hayashi*
*Department of Chemistry , Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
Imidazole and imidazoline (dihydroimidazole) derivatives can serve as simple and efficient ligands for the nickel-catalyzed Kumada-Tamao-Corriu coupling reaction. Among the imidazole and imidazoline derivatives in our investigations, the 2-phenyllimidazoline–nickel (II) chloride complex exhibited the highest catalytic activity.
Published online: 18th July, 2012
■ Ring-Opening Reactions of 2-Phenyl-1’H,5H-spiro[oxazole-4,2’-quinoxalin]-3’(4’H)-ones
Irena Mušič and Bojan Verček*
*Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana, Slovenia
Abstract
Several simple quinoxaline derivatives were prepared by ring-opening reactions of 2-phenyl-1’H,5H-spiro[oxazole-4,2’-quinoxalin]-3’(4’H)-one and its N-alkyl derivatives under various reaction conditions.
Published online: 17th July, 2012
■ Enantioselective Synthesis of cis- and trans-2-Methyl-6-nonylpiperidines: Alkaloids Solenopsin and Isosolenopsin
Mohamed Medjahdi, José Carlos González-Gómez,* Francisco Foubelo, and Miguel Yus*
*Department of Organic Chemistry, Faculty of Sciences and Institute of Organic Synthesis (ISO), University of Alicante, P.O. Box 99, 03080 Alicante, Spain
Abstract
The cross-metathesis of the enantioenriched homoallylic amine 8 (readily accessible by α-aminoallylation of decanal) with methyl vinyl ketone using the Hoveyda-Blechert catalyst 10 in presence of 10 mol% of Ti(O-i-Pr)4 led exclusively to the (E)-enone 11, which by stereoselective reductive amination affords (+)-isosolenopsin (3a) and (+)-solenopsin (4a) with excellent selectivities.
Published online: 2nd August, 2012
■ Quantitative Analysis of Cu(I) Concentration in Click Chemistry — Biotinylation at Side Chain of Propargylglycine Using Click Chemistry under Heating Conditions —
Yui Ogasawara, Yuta Murai, Yasuko Sakihama, Yasuyuki Hashidoko, and Makoto Hashimoto*
*Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
Abstract
The click reaction is one of the latest techniques for the chemical modification of bioactive compounds. Chemical modifications of α-amino acid side chains are gaining significance as useful and important tools for biochemical research. The biotin-avidin specific interaction has been extensively utilized in functional analysis. Synthesis of side chain biotinylated α-amino acid derivative using click reaction and detail quantitative analysis of Cu(I) concentration in the course of the reactions are described.