Special Issue

Ryoji Noyori's Special Issues, Vol. 76, No. 2, 2008

63 data found. 1 - 30 listed Next Last
Review | Special issue | Vol 76, No. 2, 2008, pp. 883 - 908
Published online: 29th May, 2008
DOI: 10.3987/REV-08-SR(N)4
DTBS Effect: The Unique Sterically Driven Director for α-Galactosylation

Akihiro Imamura, Hiromune Ando, Hideharu Ishida, and Makoto Kiso*

*Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan


This review outlines the chemistry of 1,2-cis glycosylations and discusses the state-of-the-art methods, highlighting the DTBS(di-tert-butylsilylene)-directed α-galactosylation that was recently developed by our group. The key feature of our unique methodology includes extremely simple procedure, namely, the introduction of cyclic DTBS protecting group into 4- and 6-OH at galacto-type glycosyl donor. The power of the methodology was demonstrated by the syntheses of biologically relevant glycans including mucin-type glycosyl amino acids [α-O-GalNAc-Ser/Thr], α-galactosyl ceramides, globo-series glycolipids.

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Review | Special issue | Vol 76, No. 2, 2008, pp. 909 - 922
Published online: 12th June, 2008
DOI: 10.3987/REV-08-SR(N)5
Catalytic Asymmetric Hydrogenation of 5-Membered Heteroaromatics

Ryoichi Kuwano*

*Department of Chemistry, Graduate School of Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan


Catalytic asymmetric hydrogenation of heteroaromatics had been a formidable issue in organic synthesis. However, the catalytic asymmetric hydrogenation has remarkably progressed during the past decade. This review surveys the recent progress of the asymmetric hydrogenation of 5-membered heteroaromatics, indoles, pyrroles, furans, and benzofurans.

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Review | Special issue | Vol 76, No. 2, 2008, pp. 923 - 947
Published online: 16th September, 2008
DOI: 10.3987/REV-08-SR(N)6
Heterocycle Formation from Zirconacycles

Lishan Zhou, Masamichi Yamanaka, Ken-ichiro Kanno, and Tamotsu Takahashi*

*Catalysis Research Center, Hokkaido University and SORST, Japan Science and Technology Agency (JST), Kita-ku, Sapporo 001-0021, Japan


Zirconium-mediated synthetic methods of a series of heterocyclic compounds were reviewed. Discussion was focused on the reactions including the other metals, such as Cu, Ni, Li, and so on. These enable us to synthesize a series of heterocycles having N, O, Si, S, Sn, etc. in the ring skeletons. The key point of the reaction is transmetalation from Zr to the other employed metals, which have a crucial role for reactivity and selectivity of the reaction.

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Review | Special issue | Vol 76, No. 2, 2008, pp. 949 - 979
Published online: 4th August, 2008
DOI: 10.3987/REV-08-SR(N)7
Recent Advances in Lewis Base-Catalyzed, Stereoselective Tandem Aldol β- and γ-Lactonizations

Vikram C. Purohit, Andrea S. Matla, and Daniel Romo*

*Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, TX, 77842-3012, USA


Stereoselective methods for the synthesis of β-lactones involving a Lewis base-promoted (nucleophile-promoted) aldol-lactonization manifold have continued to expand since the initial reports of Bormann and Wegler in the late 1960’s and later by Wynberg and Staring in the early 1980’s. This review will cover these developments including enantioselective versions of these processes. Cinchona alkaloids and various pyridine derivatives have been used most extensively to expand the repertoire of β-lactones accessible by this process. Furthermore, recent advances in the development of a3-d3-ümpolung pathways using N-heterocyclic carbenes have also enabled access to previously unattainable manifolds for the stereoselective synthesis of both β- and γ-lactones via aldol-lactonization pathways. This review covers literature in this area in the period from 1967- June 2008.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 981 - 987
Published online: 15th May, 2008
DOI: 10.3987/COM-08-S(N)36
Unexpected Cyclization Reaction of an Overcrowded 2-Phosphinophenylmethanimine Derivative Leading to the Formation of the First Stable 2-Phospha-2H-isoindole Derivative

Norihiro Tokitoh,* Teruyuki Matsumoto, and Takahiro Sasamori

*Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan


The reaction of overcrowded 2-phosphinophenylmethanimine derivative 1 bearing a 2,4,6-tri-t-butylphenyl (Mes*) group on the phosphorus atom and a 2,6-diisopropylphenyl (Dip) group on the nitrogen atom with potassium hydride afforded 2-phospha-2H-isoindole 2 along with Mes*H.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 989 - 994
Published online: 15th May, 2008
DOI: 10.3987/COM-08-S(N)57
Nucleophilic Substitution Reaction in Indole Chemistry: A Synthesis of Novel 7β-Substituted Yohimbine and 4aα-Substituted 1,2,3,4-Tetrahydro-β-carboline Derivatives

Katsumasa Yoshino, Fumio Yamada, and Masanori Somei*

*Faculty of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan


X-Ray analyses of 1-hydroxyyohimbine derivatives clearly show the deviation of the N(1)-O bond from the indole molecular plane. This phenomenon supports our working hypothesis “bishomoallylic conjugation”. The deviation is responsible for the unprecedented nucleophilic substitution reaction in 1-hydroxyindole chemistry and effected the synthesis of novel 7β-heteroarylyohimbine and 4aα-heteroaryl-1,2,3,4-tetrahydro-β-carboline derivatives from the corresponding 1-hydroxyindole derivatives.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 995 - 1000
Published online: 2nd June, 2008
DOI: 10.3987/COM-08-S(N)59
Kinetic Resolution of 1,2-Diols Using Nitrogen-Tethered Bisimidazoline-Copper(I) Catalyzed Benzoylation

Takayoshi Arai,* Tomoe Mizukami, Asami Mishiro, and Akira Yanagisawa

*Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba 263-8522, Japan


Nitrogen-tethered bisimidazoline (Nb-imidazoline) ligand was utilized in the Cu(I)-catalyzed benzoylation of 1,2-diols. With the assistance of i-Pr2NEt, the reaction of rac-1,2-diols with o-methylbenzoyl chloride was smoothly catalyzed by Nb-imidazoline-CuCl in CH2Cl2 to give the corresponding o-methylbenzoylated secondary alcohols in up to 79% ee.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1001 - 1005
Published online: 29th May, 2008
DOI: 10.3987/COM-08-S(N)62
Synthesis of γ-Valerolactones as the Tea Catechin Metabolites

Sousuke Nakano, Masahiro Hamada, Takao Kishimoto, and Noriyuki Nakajima*

*Department of Biotechnology, Faculty of Engineering, Toyama Prefectural University, Imizu, Toyama 939-0398, Japan


The synthesis of optically active γ-valerolactones in order to characterize the absolute configuration of the one of the (-)-epicatechin gallate metabolites was described. The determination of stereochemistry at C(4) position of γ-valerolactone suggested that C(3) position of tea catechins was converted to the C(4) position of γ-valerolactone by maetabolism.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1007 - 1010
Published online: 19th May, 2008
DOI: 10.3987/COM-08-S(N)63
Facile and Efficient Synthesis of 1,4-Benzodiazepines from 1,4-Naphthoquinones

Vishnu K. Tandon* and Hardesh K. Maurya

*Department of Chemistry, University of Lucknow, Lucknow - 226 007, India


Concise intramolecular cyclization reaction of 2,3-diamino-1,4-dihydro-naphthalenediones 4 and 7 in anhydrous K2CO3 /Et3N and EtOH yielded novel 1,4-benzodiazepines 5 and 6 fused with 1,4-naphthoquinone nucleus.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1011 - 1016
Published online: 19th May, 2008
DOI: 10.3987/COM-08-S(N)70
A Simple Desymmetrization Approach to the Spiroxin Framework

Kazuyuki Nabatame, Masahiro Hirama, and Masayuki Inoue*

*Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Tokyo, Japan


The highly strained hexacyclic framework of spiroxins, a family of 1,8-dihydroxynaphthalene-derived natural products, was efficiently constructed in ten steps from commercially available naphthalene-1,5-diol using a symmetry-based strategy. Key reactions in this synthesis are biaryl homocoupling, oxidative desymmetrization of a C2-symmetric intermediate, selective oxidation of the naphthalene portion, and oxidative cyclization.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1017 - 1022
Published online: 26th May, 2008
DOI: 10.3987/COM-08-S(N)97
An Easy Access to the Exocyclic Lactams Analogous of the Central Nervous System Active Tricyclic Nitroxapine, Mianserine and Chlothiapine Agents Using N-Acyliminium Chemistry

Abderrahmane Hadou, Abdulkareem Hamid, Hilarion Mathouet, Mohamed-Fadel Deïda, and Adam Daïch*

*URCOM, EA 3221, UFR of Sciences & Techniques, University of Le Havre, BP 540, 25 rue Philippe Lebon, F-76058 Le Havre Cedex, France


The conformationally restrained dibenzothia(oxa)zepines and dibenzazepines 4-6 analogous to the antidepressant Sintamil® were prepared easily by π-cationic cyclization of the N-acyliminium ions 9A-C precursors with neat trifluoroacetic acid in three step-sequence starting from available amines and anhydrides. The regioselectivity in the reduction of imides especially in the maleimide derivatives as well as in the cyclization step was also discussed.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1023 - 1026
Published online: 19th May, 2008
DOI: 10.3987/COM-08-S(N)75
Preparation and Electrochemical Property of Octabutylphthalocyanine Fused with Four TTF Units

Takeshi Kimura,* Dai Watanabe, and Toshiharu Namauo

*Center for Instrumental Analysis, Iwate University, Morioka, Iwate 020-8551, Japan


3,6-Dibutylphthalonitrile (3) fused with a TTF unit was prepared and treated with lithium in n-pentanol to produce octabutyltetrakis(tetrathiafulvaleno)phthalocyanine (5). The structure of the product was determined by 1H NMR and FAB MS. Electrochemical and optical properties of compound (5) were estimated by cyclic voltammetry and UV-vis spectroscopy.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1027 - 1031
Published online: 19th May, 2008
DOI: 10.3987/COM-08-S(N)77
Fluorous Thiazolium Salts for the Intramolecular Stetter Reaction

Osamu Hara,* Atsuko Kume, Michiharu Sugiura, and Isamu Maeba

*Faculty of Pharmacy, Meijo University, 150 Yagotoyama Tempaku-ku, Nagoya, Aichi, 468-8503 Japan


The fluorous thiazolium salt 6 derived from 5-(2-hydroxyethyl)-4-methylthiazole was employed for an intramolecular Stetter reaction. The catalytic activity of the fluorous catalyst 6 was similar to that of the standard catalyst 1. The fluorous catalyst 6 survived multiple reaction cycles.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1033 - 1042
Published online: 17th July, 2008
DOI: 10.3987/COM-08-S(N)88
Structure-Activity Relationship of Okadaic Acid, a Potent Protein Phosphatases PP1 and PP2A Inhibitor: 24-epi-Okadaic Acid and a 18-Membered Lactone Analog

Masaki Kita, Makoto Kuramoto, Tatsuhiko Chiba, Akihiro Yamada, Nobuko Yamada, Takako Ishida, Takeharu Haino, Kaoru Yamada, Yasuharu Ijuin, Osamu Ohno, and Daisuke Uemura*

*Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8602, Japan


X-Ray crystallographic analysis and structure-activity relationship of okadaic acid revealed that the flexible cavity structure stabilized by intramolecular hydrogen bonds is important for its potent cytotoxicity.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1043 - 1048
Published online: 5th June, 2008
DOI: 10.3987/COM-08-S(N)103
Synthesis, Structure, and Properties of 2,5,8,11,14,17-Hexamethyltriphenyleno[2,1-b:3,4-b’:6,5-b”:7,8-b’’’:10,9-b””:11,12-b””’]hexathiophene

Masaru Endou, Yutaka Ie, and Yoshio Aso*

*The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan


2,5,8,11,14,17-Hexamethyltriphenyleno[2,1-b:3,4-b’:6,5-b’’:7,8-b’’’:10,9-b’’’’:11,12-b’’’’’]hexathiophene has been synthesized by an iron(III)mediated oxidative cyclization of hexakis(2-methyl-4-thienyl)benzene, and its structure has been determined by an X-ray crystallographic analysis. Electronic properties were investigated by spectroscopic and electrochemical measurements.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1049 - 1055
Published online: 19th June, 2008
DOI: 10.3987/COM-08-S(N)105
Asymmetric Epoxidation of α,β-Unsaturated Ketones with Hydrogen Peroxide Catalyzed by Axially Chiral Guanidine Base

Masahiro Terada* and Megumi Nakano

*Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan


The enantioselective epoxidation of α,β-unsaturated ketones with hydrogen peroxide was demonstrated using axially chiral guanidine as a base catalyst. Hydrogen peroxide can be utilized as a cost-effective and atom-efficient oxidant in the present catalytic epoxidation even under heterogeneous conditions. The newly developed axially chiral guanidine base bearing an additional central chirality functions as an efficient catalyst to provide epoxides in 51-65% ee.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1057 - 1060
Published online: 12th June, 2008
DOI: 10.3987/COM-08-S(N)107
Deprotonative Zincation of Heteroaromatics Using ZnI2 and tert-Bu-P4 Base

Tatsushi Imahori, Koichi Suzawa, and Yoshinori Kondo*

*Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai 980-8578, Japan


The direct deprotonative zincation of diazines was accomplished using the combination of ZnI2 and t-Bu-P4 base and unique regioselectivities of zincation were observed.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1061 - 1067
Published online: 10th July, 2008
DOI: 10.3987/COM-08-S(N)111
Regioselective Mannich Reaction of Phenols under High Pressure Using Dichloromethane as C1 Unit

Kiyoshi Matsumoto,* Kouta Joho, Seisuke Mimori, Hirokazu Iida,* Hiroshi Hamana, and Akikazu Kakehi

*Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba 288-0025 Japan


Regioselectivity in Mannich reaction of 4-, 3-, and 2-substituted phenols with typical heterocyclic amines are investigated under reaction conditions developed by us. Phenol and 4-alkyl, and 4-chlorophenols in the title reaction predominantly gave the corresponding 2-(aminomethyl)phenols, while 4- methoxyphenol afforded, in addition to the mono(aminomethyl)phenols, a considerable amount of the bis adducts. Peculiarly enough, 3-methylphenol with amines afforded 3-methyl-4-(aminomethyl)phenols whereas 2-methylphenol produced 2-methyl-6-(aminomethyl)phenols.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1069 - 1074
Published online: 19th June, 2008
DOI: 10.3987/COM-08-S(N)113
Stereoselective Synthesis of Maitotoxin GHI-Ring System Having a 1,2-Diol Side Chain

Masanori Nagatomo and Tadashi Nakata*

*Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan


The stereoselective synthesis of maitotoxin GHI-ring system having a 1,2-diol side chain was accomplished via successive SmI2-induced reductive cyclizations of β-alkoxyacrylate-aldehyde and optically active (E)-β-alkoxyvinylsulfoxide-aldehyde, dihydroxylation of α,β-unsaturated δ-lactone, and Sharpless asymmetric dihydroxylation of the side chain.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1075 - 1079
Published online: 12th June, 2008
DOI: 10.3987/COM-08-S(N)117
Diastereoselective Epoxidation of Compound Bearing a Cyclohex-3-enol Moiety: Application to the Enantioselective Synthesis of (1R)-trans-Chrysanthemic Acid and (1R)-cis-Deltametrinic Acid

Alain Krief,* Stéphane Jeanmart, and Adrian Kremer

*Laboratoire de Chimie Organique de Synthèse, Facultés Universitaires N.-D. de la Paix, 61 rue de Bruxelles, Namur, B-5000, Belgium


We disclose the synthesis of enantiomeric (1S)-cis- and (1R)-cis-chrysanthemic acids precursors of S-bioallethrin and deltamethrin the most active indoor and outdoor insecticides respectively. It involves an original strategy which takes advantage of the complete stereocontrolled epoxidation of an homoallylalcohol and the synthesis in the same pot of precursors of each of the two enantiomers of cis-chrysanthemic acid, bearing functional groups possessing similar reactivity but having different structural behavior which allow their easy separation.

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Communication | Special issue | Vol 76, No. 2, 2008, pp. 1081 - 1085
Published online: 30th June, 2008
DOI: 10.3987/COM-08-S(N)123
Synthesis of Chiral Tetraaminophosphonium Chlorides from N-Boc α-Amino Acid Esters

Daisuke Uraguchi, Sawako Sakaki, Yusuke Ueki, Takaki Ito, and Takashi Ooi*

*Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan


Preparation of chiral tetraaminophosphonium chlorides of type 1 starting from N-Boc α-amino acid esters is described. Modified conditions for the displacement of the tertiary hydroxy group of the intermediary amino alcohol pave a way for the assembly of 1 with various geminal aromatic groups, particularly those having electron-withdrawing substituents.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1087 - 1102
Published online: 15th May, 2008
DOI: 10.3987/COM-08-S(N)27
Investigations on the Reactions of Thioamides and Related 1,3-Diazabuta-1,3-dienes with Dimethyl Acetylenedicarboxylate: Synthesis of Novel Functionalized Heterocycles

Alka Marwaha, Vishal Sudan, and Mohinder P. Mahajan*

*Department of Applied Chemistry, Guru Nanak Dev University, Amritsar - 143005, Punjab, India


The manuscript describes an investigation on the reaction pathways followed in the reactions of variedly substituted thioamides and the corresponding 1,3-diazabuta-1,3-dienes with dimethyl acetylene dicarboxylate. The mechanistic rationales for the reactions pathways followed have been plausibly explicated. The study assumes considerable significance because of the formation of novel functionalized heterocycles.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1103 - 1119
Published online: 15th May, 2008
DOI: 10.3987/COM-08-S(N)64
Synthesis of Thiochromans Based on Indirect Cation Pool Method

Kouichi Matsumoto, Koji Ueoka, Shunsuke Fujie, Seiji Suga,* and Jun-ichi Yoshida*

*Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan


A method for the synthesis of thiochromans based on the reactions of stilbenes and alkoxycarbenium ion pools, which were generated and accumulated by the reaction of anodically generated ArS(ArSSAr)+ with thioacetals, has been developed.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1121 - 1131
Published online: 15th May, 2008
DOI: 10.3987/COM-08-S(N)69
Crystal Structure Analysis and Reactivity of N-Alkyl- and N-Acyldioxathiazinanes

Fabrice Galaud, John W. Blankenship, and William D. Lubell*

*Department of Chemistry, University of Montreal, C.P.6128, Downtown Station. Montréal, Québec, H3C 3J7, Canada


Cyclic sulfamidates have served as reactive electrophiles for the synthesis of various products, including alkaloids, substituted amines, amino acids and lactams. N-Acyl dioxathiazinanes exhibit enhanced reactivity relative to their unsubstituted and N-alkyl counterparts, and were previously suggested to be more reactive due to carbamoylation of the -NH moiety generating an electron withdrawing effect. Probing this enhanced reactivity by the synthesis and structural analysis of N-Boc- and N-PhF-dioxathiazinanes using NMR spectroscopy, X-ray diffraction, and DFT calculations, we now describe a unique, reactive twisted conformation in N-acyl dioxathiazinanes.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1133 - 1140
Published online: 22nd May, 2008
DOI: 10.3987/COM-08-S(N)71
Synthesis of 1,2-Azulenequinone Derivatives by Bromine-Oxidation

Hidetsugu Wakabayashi,* Osamu Irinamihira, Satoshi Shibata, Teruo Kurihara, Yuzuru Uchiyama, Akira Ohta, and Kunihide Fujimori

*Department of Chemistry, Graduate School of Material Science, Josai University, Sakado, Saitama 350-0295, Japan


Treatment of 2-hydroxyazulene (1a) with 3 equiv. of C5H5N·HBr3 in aqueous THF-AcOH at 0 oC for 1 h afforded 1,1,3-tribromoazulene-2-one (5a). 3-Bromo-1,2-azulenequinone (2a) was obtained by the hydrolysis of 5a in the presence of Ag2O. Annulated compound 6 was readily obtained by the reaction of 2a with o-phenylenediamine.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1141 - 1154
Published online: 29th May, 2008
DOI: 10.3987/COM-08-S(N)73
Regioselective Synthesis of Either 1H- or 2H-1,2,3-Triazoles via Michael Addition to α,β-Unsaturated Ketones

Sen Wai Kwok, Jason E. Hein, Valery V. Fokin, and K. Barry Sharpless*

*Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, BCC 315, La Jolla, CA 92037, USA


The Michael reaction of NH-1,2,3-triazole (1) with α,β-unsaturated ketones was studied. 1H-1,2,3-triazolyl-ketones were selectively generated when 1 was combined neat with a variety of enones. The use of aprotic solvents with catalytic base gave the corresponding 2H-regioisomers. Together, these two protocols provide direct access to either the N1- or N2-substituted 1,3-triazolyl ketone regioisomers.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1155 - 1170
Published online: 22nd May, 2008
DOI: 10.3987/COM-08-S(N)74
Epimerization of trans-3-Arylaziridine-2-carboxylates at the C3 Position

Takuya Kumamoto,* Shin-ichiro Nagayama, Yukiko Hayashi, Hiroaki Kojima, Lemin David, Waka Nakanishi, and Tsutomu Ishikawa

*Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho Inage-ku, Chiba 263-8522 Japan


We describe here effective epimerization of trans to cis isomer of 1-benzyl-3-arylaziridine-2-carboxylates. The combination of samarium metal, iodine and N,N-dimethylaminoethanol promoted the epimerization of trans isomer to a ca. 1 : 1 mixture of cis and trans ones. Investigating more effective catalyst, indium chloride was found to afford a ca. 2 : 1 mixture of cis and trans isomers. Epimerization at benzylic position in the aziridines is suggested from the result with optically active ones. Preparation of cis-2-indolylaziridine towards construction of aziridinomitosene skeleton was achieved in this epimerization reaction.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1171 - 1180
Published online: 22nd May, 2008
DOI: 10.3987/COM-08-S(N)76
Dimeric Flavans from Gambir and Their Structural Correlations with (+)-Catechin

Shoko Taniguchi, Kayo Kuroda, Kou-ichi Doi, Masahiro Tanabe, Takashi Shibata, Takashi Yoshida, and Tsutomu Hatano*

*Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Tsushima, Okayama 700-8530, Japan


We isolated two new flavan dimers, gambirflavan D3 (10) and gambirflavan D4 (12), together with gambiriin A3 (11), from gambir, a hot-water extract of the leaves and young twigs of Uncaria gambir. Because their spectral analyses suggested that they are derived from catechin, we conducted a conversion reaction using (+)-catechin (1) to produce these dimers; another new flavan, gambirflavan D5 (13), was obtained as a product of this reaction. The structural relationship of these dimeric flavans with (+)-catechin (1) is discussed.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1181 - 1189
Published online: 30th June, 2008
DOI: 10.3987/COM-08-S(N)78
Synthesis of 14,15-Epoxyisoprostane A2 Phosphorylcholine

Hukum P. Acharya, Kei Miyoshi, Yuji Takashima, Narihito Ogawa, and Yuichi Kobayashi*

*Department of Biomolecular Engineering, Tokyo Institute of Technology, B52, Nagatsuta-cho 4259, Midori-ku, Yokohama 226-8501, Japan


The product of the copper-promoted allylic substitution of the 4-hydroxycyclopent-2-enyl ester with TMS-C≡CCH2MgBr was converted to the cyclopentenone with the PMBO(CH2)4CH=CHCH2 side chain. Aldol reaction of the enone with the epoxy aldehyde derived from (E)-oct-2-en-1-ol through the Sharpless asymmetric epoxidation gave the full structure of the isoprostane. Dehydration, conversion of the PMBOCH2 moiety to CO2H, and condensation with lysophosphorylcholine produced the title molecule.

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Paper | Special issue | Vol 76, No. 2, 2008, pp. 1191 - 1204
Published online: 2nd June, 2008
DOI: 10.3987/COM-08-S(N)81
A New Chiral Synthesis of a Bicyclic Enedione Containing a Seven-Membered Ring Mediated by a Combination of Chiral Amine and Brønsted Acid

Takashi Nagamine, Kohei Inomata,* and Yasuyuki Endo*

*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan


Several chiral amines bearing a heterocyclic moiety such as pyrrolidine, piperazine or tetrazole were prepared from L-phenylalanine. The enantioselectivity of the intramolecular asymmetric aldol reaction mediated by a combination of the synthetic chiral amine and a Brønsted acid to construct an enedione containing a seven-membered ring was examined in detail. A remarkable increase of enantioselectivity depending on the amount of Brønsted acid was observed.

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63 data found. 1 - 30 listed Next Last