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Published online: 23rd October, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)94
Lithium tert-Butoxide-mediated Carboxylation Reactions of Unprotected Indoles and Pyrroles with Carbon Dioxide

Woo-Jin Yoo, Thanh V. Q. Nguyen, Montse Guiteras Capdevila, and Shū Kobayashi*

*Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Abstract

Unprotected indoles and pyrroles were found to undergo base-mediated carboxylation reactions under ambient pressure of carbon dioxide. It was found that this transition metal-free carboxylation reaction proceeded smoothly with the use of a large excess of LiOtBu.

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Published online: 21st October, 2014

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-14-13087
1-Hydroxyethylhalenaquinone: A New Proteasome Inhibitor from the Marine Sponge Xestospongia Sp.

Michiko Yamakuma, Hikaru Kato, Kanae Matsuo, Ahmed H. El-Desoky, Tetsuro Kawabata, Fitje Losung, Remy E. P. Mangindaan, Nicole J. de Voogd, Hideyoshi Yokosawa, and Sachiko Tsukamoto*

*Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan

Abstract

A new halenaquinone derivative, 1-hydroxyethylhalenaquinone (1), was isolated from the marine sponge Xestospongia sp. as a proteasome inhibitor together with three known compounds, halenaquinone (2) and 3-ketoadociaquinones A (3) and B (4). 1-Hydroxyethylhalenaquinone (1) was the first halenaquinone derivative containing an alkyl group at the keto-furan C-1 position. Compounds 1 and 2 inhibited the chymotrypsin-like activity of the proteasome with IC50 values of 0.19 and 0.63 μM, respectively, whereas 3 or 4, each containing a thiomorpholine 1,1-dioxide moiety, scarcely inhibited its activity, even at a concentration of 5 μM.

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Published online: 20th October, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)102
Synthesis of 2,7-Disubstituted 5,10-Diaryl-5,10-dihydrophenazines via Iron-catalyzed Intramolecular Ring-Closing C–H Amination

Yuma Aoki, Ryuji Imayoshi, Takuji Hatakeyama, Hikaru Takaya, and Masaharu Nakamura*

*International Research Center for Elements Science, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan

Abstract

A novel iron-catalyzed intramolecular ring-closing C–H amination reaction of o-phenylenediamines was developed, affording the corresponding 2,7-disubstituted 5,10-diaryl-5,10-dihydrophenazines in acceptable yields. The reaction proceeded via the in-situ generation of the magnesium amides of the starting secondary amines in the presence of a catalytic amount of an iron salt and a stoichiometric amount of 1,2-dibromoethane as the terminal oxidant. The substituted dihydrophenazine derivatives can potentially be used as hole-injection materials in organic electroluminescence (OEL) devices and also offer scaffolds for further synthetic elaborations of OEL materials.

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Published online: 20th October, 2014

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-14-13091
Synthesis of 7-Amino-5,8-dihydropyrido[2,3-d]pyrimidine-6-carbonitrile Derivatives Based on the Reaction of 4-Chloro-5-lithio-6-methoxypyrimidines with 2-(Arylmethylidene)propanedinitriles

Kazuhiro Kobayashi,* Shohei Yuba, Aina Taniguchi, Hiroki Inouchi, Hidetaka Hiyoshi, and Kazuto Umezu

*Division of Applied Chemistry, Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

This paper describes a simple and efficient method for the preparation of 7-amino-5,8-dihydropyrido[2,3-d]pyrimidine-6-carbonitrile derivatives starting from readily available and inexpensive chemicals. Thus, the reaction of 4-chloro-5-lithio-6-methoxypyrimidines, generated by the treatment of 4-chloro-6-methoxypyrimidines with LDA, with 2-(arylmethylidene)propanedinitriles in THF at –78 ˚C provided the corresponding conjugate addition products, 2-[aryl(4-chloropyrimidin-5-yl)methyl]propanedinitrile derivatives, in fair to good yields. These adducts were then treated with alkylamines in refluxing 1,2-dimethoxyethane (DME) in the presence of triethylamine to result in the formation of the desired products in moderate to fair yields.

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Published online: 17th October, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)69
Comparison of Photochemical Reactions of Aromatic Carbonyl Compounds with a Silyl Ketene Thioacetal and a Silyl Ketene Acetal

Gyeong Min Moon, Suk Hyun Lim, Dae Won Cho,* Sung Hong Kim, In Ok Lee, Ung Chan Yoon, and Patrick Mariano*

*Department of Chemistry and Chemical Biology, University of New Mexico, Albuequerque, NM 87131, U.S.A.

Abstract

Photoaddition reactions of carbonyl compounds with silyl ketene thioacetals have been explored and the results are compared to those arising from investigations of analogus reactions with silyl ketene acetals. Observations made in this study show that photoirradiation of benzaldehyde (8) and benzophenone (9) and with the dimethyl substituted silyl ketene thioacetal (13) promotes reactions that take place predominantly via Paterno-Büchi type [2+2]-cycloaddition pathways to produce oxetanes. In addition, photoreactions between acetophenone (10) and p-cyanoacetophenone (11) and 13 occur via competitive sequential single electron transfer (SET)-desilylation or [2+2]-cycloaddition modes. Lastly, photochemical reaction of the highly electron deficient carbonyl compound, p-trifluoromethylacetophenone (12), and 13 gives rise to exclusive formation of β-hydroxythioester arising via the SET pathway. In contrast, photochemical reactions of all of these aromatic carbonyl compounds with the analogous dimethyl substituted silyl ketene acetal 14 take place predominantly via a sequential SET-desilylation pathway to form β-hydroxyesters. A comparison of these results reveals that replacement of an alkoxy by alkylthio group in the ketene derivatives brings about dramatic changes in chemoselectivities of the photoreactions with aryl-substituted ketones.

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Published online: 14th October, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)103
Stereoselective Aza-Henry Reaction of Chiral tert-Butanesulfinyl Imines with Methyl or Ethyl 4-Nitrobutanoate: Easy Access to Enantioenriched 6-Substituted Piperidine-2,5-diones

M. Jesús García-Muñoz, 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 base-catalyzed addition of 4-nitrobutanoates 6 to N-tert-butanesulfinyl imines 8 under solvent-free reaction conditions proceeded with high face diastereoselectivity. The resulting β-nitroamine derivatives 9 were easily transformed into 6-substituted piperidine-2,5-diones 11 upon removal of the sulfinyl group with concomitant δ-lactam formation and functional group transformation under Nef reaction conditions.

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Published online: 10th October, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)80
Palladium Catalyzed Intramolecular Vinylselenation and Vinylthiolation of Allenes

Susumu Tsuda, Maiko Okuyama, Shin-ichi Fujiwara,* Takanori Iwasaki, Hitoshi Kuniyasu, and Nobuaki Kambe*

*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

Abstract

Intramolecular vinylselenation of allenes 1a,b proceeds in the presence of Pd(0) catalyst producing pyridin-2-one derivatives 2a,b having a high degree of unsaturation as a sole product. This cyclization could also be applied to vinylthiolation and to the construction of seven-membered lactams.

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Published online: 8th October, 2014

Paper | Regular issue | Prepress
DOI: 10.3987/COM-14-13077
The Reaction of 2-((Trimethylsilyl)methyl)-2H-tetrazoles with Aldehydes and Ketones in the Presence of 1,8-Diazabicyclo[5.4.0]undec-7-ene

Hideaki Umemoto,* Takuya Onaka, Yasuyoshi Miki, Akira Nakamura, and Tomohiro Maegawa*

*Business Development Department, FUJIMOTO CHEMICALS Co., Ltd., 1-2-38 Kinrakuji-cho, Amagasaki, Japan

Abstract

2-((Trimethylsilyl)methyl)-2H-tetrazoles were treated with aldehydes and ketones in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give 2-(2-hydroxyethyl)-2H-tetrazoles. This simple procedure offers a valuable strategy for the preparation of 2-(hydroxyethyl)-2H-tetrazoles.

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Published online: 6th October, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)44
Redox Responsive Polymer Incorporated with Mesogenic Unit and Bis(benzodithiolyl)bithienyl Scaffold

Toshihiro Ohtake,* Hideki Tanaka, Tetsuro Matsumoto, Mutsumi Kimura, and Akira Ohta*

*Department of Chemistry, Faculty of Science, Shinshu University, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan

Abstract

A redox-active polymer consisting of a poly(siloxane) backbone, a liquid crystalline (LC) unit, and bis(benzodithiolyl)bithienyl moieties was designed and synthesized. The resulting polymer after the incorporation of the redox-active and LC functional units into the poly(siloxane) backbone exhibits a redox response associated with the electrochemical interconversion of the bis(benzodithiolyl)bithienyl moieties.

Supporting Info. (1.7MB)PDF (751KB)

Published online: 3rd October, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)88
Natural-Product-based Insecticidal Agents 16. Semisynthesis of C7-Oxime Sulfoate Ester Derivatives of Obacunone as Insecticidal Agents against Mythimna Separata Walker

Xiang Yu, Guodong Ding, Zhinan Gao, Jing Zha, and Hui Xu*

*Laboratory of Pharmaceutical Design & Synthesis, College of Life Sciences, Northwest A & F University, Xinong Road 22#, Yangling, Shaanxi, 712100, China

Abstract

A series of novel C7-oxime sulfonate ester derivatives of obacunone (3a-f) were synthesized. Their insecticidal activity was also evaluated at the concentration of 1 mg/mL against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker), a typical lepidopteran pest. Especially C7-oxime p-ethylphenylsulfonate ester of obacunone (3d) exhibited more potent insecticidal activity than their precursor obacunone and toosendanin (a positive control).

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Published online: 3rd October, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)73
Structural and Ecotoxicological Profile of N-Alkoxymorpholinium-based Ionic Liquids

Robert Salchner, Gerhard Laus, Simone Haslinger, Volker Kahlenberg, Klaus Wurst, Doris E. Braun, Stefan Vergeiner, Holger Kopacka, Herwig Schottenberger,* Alan Puckowski, Marta Markiewicz, Stefan Stolte, and Sven Nerdinger*

*Faculty of Chemistry and Pharmacy, Leopold-Franzens University, Innrain 80, 6020 Innsbruck, Austria

Abstract

Alkylation of N-methylmorpholine N-oxide (1, NMMO) using dialkyl sulfates gave N-alkyloxymorpholinium alkyl sulfates 2 and 3 (alkyl = Me, Et), which were subjected to ion metathesis. The tetrachloroferrates(III) 4 and 5 were found to be advantageous precursors for the chlorides 6 and 7 which were converted to six other salts. In summary, 13 new quaternary salts were prepared (IO4 8 and 9, BF4 10, N3 11, AcO 12, (MeO)2PO2 13, PF6 14, Tf2N 15) and one hydrate 7·H2O. Eleven X-ray crystal structures were determined. Nine salts had melting points below 100 °C, thus qualifying as ionic liquids (ILs), and three more below 110 °C. In addition, catalytic hydrogenation gave two protic ionic liquids (PILs), N-methylmorpholinium alkyl sulfates 16 and 17 (alkyl = Me, Et). This reductive degradation was also performed in aqueous solution. Ecotoxicological examinations of 3, 4, and 5 showed minor potential to interact with acetylcholinesterase (AChE), moderate acute toxicity towards rat leukemia IPC-81 cells, no adverse effect towards green algae Scenedesmus vacuolatus, but no ready biodegradability in sewage sludge.

Supporting Info. (1.9MB)PDF (1.2MB)

Published online: 1st October, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)70
Selective Adsorption of Mercury(II) Ion by p-tert-Butylcalix[4]thiacrown-5 at a Solid-Liquid Interface

Tatsuya Takimoto,* Hirohito Tsue, Rui Tamura, and Hideaki Sasaki

*Division of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, 1-1-3 Minatojima, Chuo-ku, Kobe 650-8586, Japan

Abstract

The solid-liquid adsorption behavior of p-tert-butylcalix[4]thiacrown-5 for heavy metal picrates has been studied. Of four heavy metal ions examined herein, mercury(II) ion was selectively adsorbed, and the saturated adsorption capacity reached to 7.3 ± 0.5 mg g–1.

Supporting Info. (59KB)PDF (212KB)

Published online: 1st October, 2014

Review | Special issue | Prepress
DOI: 10.3987/REV-14-SR(K)3
Terpenoids bearing the 7-Oxabicyclo[2.2.1]heptane (7-Oxanorbornane) Skeleton. Natural Sources, Biological Activities and Chemical Synthesis

Silvia Roscales and Joaquín Plumet*

*Química Orgánica, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid, Spain

Abstract

Compounds bearing the 7-oxabicyclo[2.2.1]heptane (7-oxanorbornane) subunits have been used extensively in the synthesis of a large array of complex organic structures. The ease of synthesis of compounds having this substructure in enantiomerically pure form, using Diels-Alder chemistry, is today an almost routinely experimental work. Moreover, the reactivity of these compounds, easily controllable and almost always associated to its ring-strain, makes them particularly valuable chiral building blocks. However, the presence of compounds showing this bicyclic skeleton in Nature has attracted less attention despite its relatively broad distribution. Many of these compounds have been shown to possess important biological activities presenting, in cases, unprecedented biogenetic origin. In addition, some of them have been considered as convenient synthetic targets enabling the development of new synthetic methodologies. In this article we have reviewed different families of terpenoids having in its structure this bicyclic subunit, paying particular attention to their natural sources, biosynthesis, biological activity and chemical synthesis.

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Published online: 26th September, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)87
Marine Natural Occurring 2,5-Diketopiperazines: Isolation, Synthesis and Optical Properties

Rémi Laville, Thanh Binh Nguyen, Céline Moriou, Sylvain Petek, Cécile Debitus, 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

Seven 2,5-diketopiperazines (DKPs) were isolated from the Fijian marine sponge Acanthella cavernosa. NMR and circular dichroism (CD) comparison with synthetic L-L DKPs allowed us to determine unambiguously the L-L absolute configuration of the natural DKPs. This work initiated the setting up of an optical properties database of natural DKPs, including specific rotation and CD.

Supporting Info. (4.3MB)PDF (345KB)

Published online: 26th September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)81
Synthesis of 1,2-Dialkynyldisilanes incorporated in 10-Membered-Ring System

Yoshiyuki Mizuhata, Yasunobu Egawa, Takahiro Sasamori, and Norihiro Tokitoh*

*Division of Synthetic Chemistry, Organoelement Chemistry, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan

Abstract

The reduction of a bis(dichloroethynylsilane) bridged by o-xylylene by lithium naphthalenide afforded trans- and cis-isomers of novel 10-membered-cyclic disilanes. Their structures were characterized by X-ray crystallographic analysis, showing the strain around the CC bonds and the close distances between two ethynylene moieties.

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Published online: 22nd September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)108
Synthesis and Preliminary Biological Evaluation of 2-[3-(Tetrazolyl)propyl]-1α,25-dihydroxy-19-norvitamin D3

Masashi Takano, Erika Higuchi, Kazunari Higashi, Keisuke Hirano, Akiko Takeuchi, Daisuke Sawada, and Atsushi Kittaka*

*Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Teikyo University, 1091-1 Suarashi, Midori-ku, Sagamihara, Japan

Abstract

Four new 19-norvitamin D3 analogs, 2α-[3-(tetrazol-1-yl)propyl]-, 2β-[3-(tetrazol-1-yl)propyl]-, 2α-[3-(tetrazol-2-yl)propyl]-, and 2β-[3-(tetrazol-2-yl)propyl]-1α,25-dihydroxy-19-norvitamin D3 were synthesized. Among them, 2α-[3-(tetrazol-1-yl)propyl]-1α,25-dihydroxy-19-norvitamin D3 showed weak binding affinity for vitamin D receptor (VDR) (2.6% of 1α,25-dihydroxyvitamin D3: ca. 15% of 1α,25-dihydroxy-19-norvitamin D3) and weak VDR transactivation activity in human osteosarcoma cells, which was determined by luciferase assays (EC50 7.3 nM, when 1α,25-dihydroxyvitamin D3 0.23 nM). Although the other three compounds could not act as VDR binders by evaluation of the competition assays, 2α-[3-(tetrazol-2-yl)propyl] analog showed weak transactivation activity (EC50 12.5 nM).

PDF (340KB)

Published online: 19th September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)39
An Efficient Domino Sonogashira/Double Carbopalladation/C–H-Activation Reaction Leading to Fluorescent Polycyclic Aromatic Hydrocarbons

Lutz F. Tietze* and Christoph Eichhorst

*Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstr. 2, D-37077 Göttingen, Germany

Abstract

A facile synthesis of fluorescent polycyclic aromatic hydrocarbons through a highly productive palladium-catalyzed fourfold domino Sonogashira/double carbopalladation/C–H-activation process was developed.

Supporting Info. (1.4MB)PDF (376KB)

Published online: 19th September, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)109
Synthesis and Structural Analysis of Nine-Membered Enyne Nitrogen Heterocycles

Kazunobu Igawa, Takeshi Kawabata, Kazuhiro Uehara, and Katsuhiko Tomooka*

*Institute for Materials Chemistry and Engineering (IMCE), Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan

Abstract

An efficient approach to the nine-membered enyne nitrogen heterocycle 3 is presented. 1H NMR analysis reveals that both 3a (R = H, X = Ts) and 3b (R = Me, X = Ts) exhibit significant labile planar chirality in solution at ambient temperature. The X-ray analysis of 3b shows that the enantiotopic faces of the alkene are differentiated by the alkyne moiety in the solid state.

PDF (345KB)

Published online: 18th September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)106
Toward the Pluramycins: Route Exploration from Dihydroxyanthrone Tricyclic Platform to an Aglycon, Saptomycinone B

Kei Kitamura, Yoshio Ando, Yoshihiko Maezawa, Takashi Matsumoto,* and Keisuke Suzuki*

*Depatrtment of Chemistry, Tokyo Institute of Technology, 2-12-1,Oh-Okayama, Meguro-ku, Tokyo 152-8552, Japan

Abstract

In connection with the total synthesis of the pluramycin-class antibiotics, we recently found dihydroxyanthrone derivatives to be suitable platforms for the installation of bis-C-glycosides. As a basis for the total synthesis, we explored viable routes to construct the characteristic tetracyclic skeleton. By setting saptomycinone B (5) as a model target, anthrone 6 was combined with the side chain moiety to access key intermediate 9, from which two viable routes have been developed. One of the routes has been exploited in the realization of our recent total synthesis of saptomycin B (4).

PDF (573KB)

Published online: 16th September, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)97
Regioselective Introduction of Substituents to the meso-Position of Pyrromethenone Derivative – Application to the Synthesis of Sterically Fixed Phytochrome Chromophore Anchored to the C15 meso-Position

Yudai Tanaka, Ryoji Iwamoto, Ryo Sakata, Takahiro Soeta, Kohei Endo, Shuhei Fujinami, Katsuhiko Inomata, and Yutaka Ukaji*

*Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan

Abstract

Pyrromethenone derivatives corresponding to the CD-ring component of phycocyanobilin chromophore were regioselectively brominated with NBS at the meso-position retaining the stereochemistry of the olefinic carbon skeleton. Subsequent introduction of carbon-substituents to the brominated pyrromethenones was accomplished by treating with Grignard reagents to afford meso-alkylated (E)-isomers regardless of the stereochemistry of the starting brominated pyrromethenones. The resulting product was applied to the synthesis of a meso-anchored sterically fixed tetrapyrrole chromophore.

PDF (459KB)

Published online: 12th September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)107
Synthesis of the C1-C7 and C8-C18 Segments of ent-Amphidinin A

Haruaki Ishiyama, Masahiro Hangyou, Ayumi Nakatsu, Yuta Mori, and Jun'ichi Kobayashi*

*Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan

Abstract

A stereoselective synthesis of the C1-C7 and C8-C18 segments of the enantiomer of amphidinin A, a cytotoxic polyketide from the culture cells of a symbiotic marine dinoflagellate Amphidinium sp. (strain Y-5), has been achieved, utilizing sulfone-aldehyde coupling, Sharpless asymmetric dihydroxylation, Katsuki-Sharpless asymmetric epoxidation, and Julia-Kocienski olefination.

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Published online: 11th September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)83
Chiral Primary Amino Amide Alcohol Organocatalyst for the Asymmetric Michael Addition of 4-Hydroxycoumarin with α,β-Unsaturated Ketones

Jun Kumagai, Yoshihito Kohari, Chigusa Seki, Koji Uwai, Yuko Okuyama, Eunsang Kwon, and Hiroto Nakano*

*Department of Applied Chemistry, Graduate School of Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran, Hokkaido 050-8585, Japan

Abstract

Chiral primary amino amide organocatalysts were designed and synthesized as new organocatalysts for the enantioselective Michael addition of 4-hydroxycoumarin with α,β-unsaturated ketones to produce chiral warfarin (up to 56% ee with up to 92% yield).

PDF (602KB)

Published online: 11th September, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)99
Solution-Phase-Peptide Synthesis without Purification of Column Chromatography and Recrystallization by protecting Amino Acid Esters with Phosphinyl Chloride

Guanghui An, Wei Zhou, Xiaokang Xu, Yi Pan, and Guigen Li*

*Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, U.S.A.

Abstract

Biphenyl phosphinyl chloride (Bpp-Cl) has been successfully applied for the amino acid GAP (Group-Assisted Purification) protection. The resulting N-protected amino acid esters have been readily converted into the corresponding amino acids and peptides through GAP operation. Biphalin, enkephalin derivatives and the fragments of surfaxin have also been synthesized via GAP work-up by avoiding column chromatography. The GAP protecting group (Bpp) can be recovered and can implement the former phosphonyl groups in peptide synthesis.

PDF (351KB)

Published online: 11th September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)92
Synthesis of Pyrrolidinofullerenes via Single Electron Transfer Reaction of Aryldienamines with C60

Naohiko Ikuma,* Hiroyuki Yamamoto, Ken Kokubo, and Takumi Oshima

*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

Abstract

Variously aryl-substituted pyrrolidinofullerenes were synthesized via a single electron transfer (SET) reaction of diaryldienamines with C60 and the following consecutive 1,6-hydrogen shift and the [3 + 2] cycloaddition of the generated radical ion pair. The LUMO levels of pyrrolidinofullerenes were ca. 0.1 eV higher than C60, consequently suppressing the bisadduct formation. The phenyl –substituted pyrrolidinofullerene 2a representatively exhibited the protic acid-catalyzed intramolecular Friedel–Crafts cyclization and the DDQ induced oxidative reversion into C60.

Supporting Info. (494KB)PDF (751KB)

Published online: 10th September, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)96
Efficient Preparation of a Versatile Chiral Synthon for 1,2-Diamines via the Fe(III)-Catalyzed Diastereoselective Oxidation of 2-Imidazolone and Its Application

Hirofumi Matsunaga,* Iori Eshita, Shin Ando, and Tadao Ishizuka*

*Department of Pharmaceutical Sciences, Graduate School of Life Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan

Abstract

The efficient and predominant preparation of (4S,5S)-4,5-dimethoxy-2-imidazolidinone (DMIm) was established via the Fe(III)-catalyzed diastereoselective oxidation of 1-[(1S,2R)-2-exo-alkoxyapocamphanecarbonyl]-2-imidazolone with aqueous H2O2 up to 94% d.e., both of which were easily purified by column chromatography, followed by simple and convenient conversions. The obtained N-tosyl-(4S,5S)-DMIm proved to be a versatile chiral synthon for 1,2-diamines by the synthesis of (1S,2S)-1,2-diamino-1-(4-fluorophenyl)butane derivative, whose platinum complex showed potent antitumor activity.

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Published online: 8th September, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)98
Synthesis of Intermediary P3 Phosphazenium Framework and Its Derivatization to Chiral Cationic Macrocycles Including Two P3 Phosphazenium Units with Hydrogen Bond Donor Sites

Masahiro Terada,* Kengo Goto, Takashi Ikehara, and Azusa Kondoh

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

Abstract

A new synthetic route to key intermediary phosphonium possessing a P3 phosphazene framework was developed. The reaction of the obtained intermediary phosphonium with chiral diamine, (1S,2S)-1,2-diphenyl-1,2-ethanediamine, resulted in the formation of 18-membered macrocyclic bisphosphazenium, the structure of which was verified by single-crystal X-ray diffraction analysis. The macrocyclic bisphosphazenium showed potential application as a chiral anion receptor and a chiral template in asymmetric catalysis.

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Published online: 5th September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)100
Thiazole/thiazolone-fused Cycloheptatrienyl Phosphonates: Reactions of 2H-Cyclohepta[d]thiazole-2-thione and -2-one with Phosphites

Ohki Sato* and Ikumi Suzuki

*Department of Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570 , Japan

Abstract

2H-Cyclohepta[d]thiazole-2-thione reacted with either trimethyl or dimethyl phosphite to furnish dimethyl 2-methylthio-4H-cyclohepta[d]thiazole-4-phosphonate and the regioisomers, 6- and 8-phosphonates. In the reaction with triphenyl phosphite, the successive S-methylation by methyl iodide and hydrolysis afforded an isomeric mixture of diphenyl 4-, 6- and 8-phosponates. Treatment of the oxygen analogue, 2H-cyclohepta[d]thiazol-2-one and triphenyl/diphenyl phosphite with/without hydrolysis gave diphenyl 3,4-dihydro-2H-cyclohepta[d]thiazol-2-one-4-phosphonate and the isomeric 6- and 8-phosphonates.

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Published online: 3rd September, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)79
Simple, Selective, and Practical Synthesis of 2-Substituted 4(3H)-Quinazolinones by Yb(OTf)3-Catalyzed Condensation of 2-Aminobenzamide with Carboxamides

Tsutomu Yoshimura, Di Yuanjun, Yu Kimura, Hisatsugu Yamada, Akio Toshimitsu, and Teruyuki Kondo*

*Advanced Biomedical Engineering Research Unit, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan

Abstract

A simple, selective, and practical synthetic method of 4(3H)-quinazolinones is realized by Yb(OTf)3-catalyzed condensation of 2-aminobenzamide with carboxamides. As the reaction proceeds, NH3 and H2O were formed as byproducts; however, Yb(OTf)3 can operate as an efficient Lewis acid catalyst without deactivation.

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Published online: 3rd September, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)74
Simple Synthetic Method for 1-Hydroxyindole and Its Application to 1-Hydroxytryptophan Derivatives

Toshiya Kawasaki, Mutsuko Tabata, Kyoko Nakagawa, Kensuke Kobayashi, Atsushi Kodama, Tetsuya Kobayashi, Masakazu Hasegawa, Keiko Tanii, 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

Simple and general synthetic method for 1-hydroxy- and 1-methoxyindole is reported. Its application to the synthesis of various types of 1-hydroxy- and 1-methoxyindole derivatives is successful, especially for the synthesis of 1-hydroxytryptophan derivatives.

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Published online: 2nd September, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)65
Three-Component Coupling Reaction of Enynes, Carbonyls, and Organozinc Reagents

Yuki Ohira, Takamichi Mori, Maya Hayashi, Gen Onodera, and Masanari Kimura*

*Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

A mixture of t-butylzinc halide and an aldehyde reacts with enyne to provide homopropargyl alcohol in a 1,2-addition manner. Under carbon dioxide at atmospheric pressure, three components (t-butylzinc halide, enyne, and carbon dioxide) combine in a 1:1:1 ratio to give allenyl carboxylic acids in a 1,4-addition manner. These products are useful for the synthesis of heterocyclic compounds such as α,β-unsaturated γ-butyrolactones.

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