Prepress

Regular & Special Issues

113 data found. 1 - 30 listed Next Last

Published online: 16th January, 2017

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)73
α-Functionalization of Tetrahydroisoquinolines with Activated Alkyl Bromide under Photoredox Catalysis

Takafumi Ide, Kazunori Shimizu, Yuji Kawato, Hiromichi Egami, and Yoshitaka Hamashima*

*School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan

Abstract

Benzylic C-H functionalization of N-aryl-tetrahydroisoquinolines (THIQs) with various benzyl bromides was developed using a photoredox iridium (Ir) catalyst under blue LED irradiation, affording arylmethyl group-substituted THIQs in moderate to good yields (up to 82%). This photoredox catalyst-mediated reaction was also applicable to other activated bromides, including allyl bromide, cinnamyl bromide, propargyl bromide, and α-bromoacetate. We propose that photoredox catalyst-mediated electron transfer generates a radical species from the THIQ and another radical from the bromide, and then radical-radical cross-coupling occurs to form a new carbon-carbon bond.

Supporting Info. (9MB)PDF (1.2MB)

Published online: 16th January, 2017

Review | Special issue | Prepress
DOI: 10.3987/REV-16-SR(S)5
Synthesis of Caprazamycins and Related Natural Products

Takumi Watanabe*

*Institute of Microbial Chemistry, Tokyo (BIKAKEN), 3-14-23 Kamiosaki Shinagawa-ku, Tokyo 141-0021, Japan

Abstract

Caprazamycins are the lead compound for CPZEN-45, which exhibits activity against extensively drug resistant tuberculosis (XDR-TB) and is currently under preclinical studies. The development of an efficient synthetic route to caprazamycins and related compounds is expected to facilitate structure-activity relationship studies on anti-TB agents. This review summarizes current synthetic strategies for caprazamycins, liposidomycins, caprazol, and CPZEN-45, with a particular focus on stereocontrol and diazepanone ring formation.

PDF (1.9MB)

Published online: 13th January, 2017

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)61
A Double Hemiketal Formation/Hetero-Michael Addition Approach to the [6,5,5]-Dispiroketal System of Spirolides

Hiroyuki Yamakoshi, Akinori Toita, Toshihiro Igari, Keisuke Takeda, Shunichi Hashimoto, and Seiichi Nakamura*

*Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan

Abstract

An approach to the [6,5,5]-dispiroketal ring system of spirolides is described. It was found that cisoid isomers, which suffered from a destabilizing dipoledipole interaction, were preferentially formed over transoid isomers by a double hemiketal formation/hetero-Michael addition sequence regardless of the reaction conditions used. However, the stereochemistry at C12 was controlled by the methyl group at C13, resulting in the preferential formation of undesired 12S isomers. As expected from precedents, the desired isomer could be obtained upon exposure of the 12R isomer, formed by the sequence, to TsOH in benzene, albeit in a ratio of 1:3 favoring its C15-epimer.

Supporting Info. (1.8MB)PDF (1.3MB)

Published online: 29th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)78
Palladium- and Norbornene-Catalyzed Synthesis of Highly Functionalized Thiophenes: The Remarkable Effect of Electron-Poor Olefins as Ligand

Nicola Della Ca’,* Elena Motti, Giovanni Maestri, and Max Malacria*

*ICSN CNRS UPR2301, 1 Av. de la Terrasse, Bat. 27, 91198 Gif s/Yvette, France

Abstract

Highly functionalized heterocyclic compounds were synthesized by palladium and norbornene catalysis starting from ortho-substituted aryl iodides, aryl bromides and 3,4-ethylenedioxythiophene. The addition of methyl cinnamate to the reaction mixture was found to be crucial in order to obtain selectively the unsymmetrical product.

Supporting Info. (1.4MB)PDF (420KB)

Published online: 29th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)43
Catalytic Aromatic Borylation via in Situ-Generated Borenium Species

Fumiya Kitani, Ryo Takita,* Tatsushi Imahori, and Masanobu Uchiyama*

*RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan

Abstract

We have developed a catalytic direct borylation of arenes via in situ-generated borenium species. The choice of appropriate Lewis base was crucial to achieve the catalytic system. Electron-rich arenes were borylated in a regioselective manner.

Supporting Info. (949KB)PDF (2.5MB)

Published online: 29th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)79
Synthetic Studies of Liposidomycin Degradation Product: Model Studies of Diazepanone Ring Construction

Noriyuki Nakajima,* Taichi Seida, Ai Furuno, Takayuki Asahi, Takao Kishimoto, and Masahiro Hamada

*Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan

Abstract

The model studies of diazepanone ring construction of liposidomycin degradation product was described. A synthesis of the liposidomycin diazepanone ring system using 2-nitrobenzenesulfonamides (N-Ns) as an activating and a protecting group has been achieved. Under the intramolecular Mitsunobu reaction conditions, the cyclization reaction proceeded efficiently to give seven-membered ring systems.

PDF (466KB)

Published online: 29th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)41
Depsidones and Diaryl Ethers from the Vietnamese Lichen Parmotrema mellisii

Duy Hoang Le, Yukiko Takenaka, and Takao Tanahashi*

*Kobe Pharmaceutical University, 4-19-1 Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan

Abstract

The Vietnamese lichen Parmotrema mellissii of the family Parmeliaceae was chemically investigated to isolate five new depsidones (1, 6, 911) and three new diaryl ethers (3, 4, 7) along with seventeen known lichen substances. Their structures were determined by spectroscopic methods.

PDF (441KB)

Published online: 29th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)87
Synthesis of Porphyrin-Polythiophene Nanotubes and Their Zinc Complex and Silver Nanoparticle Composites

Noritaka Takeuchi, Saya Ueda, Tsukasa Nakahodo, and Hisashi Fujihara*

*Department of Applied Chemistry, Kindai University, Kowakae, Higashi-Osaka 577-8502, Japan

Abstract

The template-based electropolymerization of terthienyl-porphyrin, 1, and its zinc porphyrin, Zn-1, in a nanoporous alumina template produced the corresponding new porphyrin nanotubes, poly-1 NTs and poly-Zn-1 NTs, respectively. The encapsulation of silver nanoparticles into the inner cavity of the poly-1 NTs provides the silver nanoparticle-porphyrin hybrid NTs.

PDF (1.8MB)

Published online: 29th December, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13616
One-Pot Synthesis of Imidazo[1,5-c]pyrimidine Derivatives from a 4,6-Dichloropyrimidine Derivative and Benzyl Isocyanides

Kazuhiro Kobayashi,* Daiki Fujiwara, Yuuho Shigemura, 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

A convenient method for the synthesis of imidazo[1,5-c]pyrimidine derivatives has been developed. Thus, benzyl isocyanides are treated with sodium hydride in DMF at 0 ˚C to generate the corresponding benzyl anions, which are allowed to react with 4,6-dichloro-2-(methylsulfanyl)pyrimidine (DCSMP) to afford 1-aryl-7-chloro-5-(methylsulfanyl)imidazo[1,5-c]pyrimidines in one pot in moderate yields.

PDF (179KB)

Published online: 27th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)75
Reversibility of 3-Phenyl-2-oxindole Dimer Formation: Application to Construct Compounds with Two Distinct Vicinal All-Carbon Quaternary Centers

Yoshihiro Sohtome,* Masumi Sugawara, Daisuke Hashizume, Daiki Hojo, Miki Sawamura, Atsuya Muranaka, Masanobu Uchiyama, and Mikiko Sodeoka*

*Synthetic Organic Chemstry Laboratory, RIKEN, 351-0198, Japan

Abstract

Here we describe the critical role of the C(3) phenyl ring in providing selective access to the meso-dimer of N-Boc-3-phenyl-2-oxindole, which contains two contiguous all-carbon quaternary centers. Solid-state analysis of the meso-dimer suggested that weak CH/O and CH/ interactions cooperatively decrease the energy of the ground state in the (±)-sc (synclinal) conformation. Solution-state analyses and DFT calculations revealed that the C(3)–C(3’) σ-bond of the meso-dimer is labile, and the phenyl group at the C(3) position makes a key contribution to stabilizing the monomeric radical species. Based on these findings, we developed a facile radical-based transformation of the meso-dimer to construct a variety of compounds with two distinct contiguous all-carbon centers.

Supporting Info. (2.7MB)PDF (4MB)

Published online: 26th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)57
Huisgen Cycloaddition with Acetylene Gas by Using an Amphiphilic Self-Assembled Polymeric Copper Catalyst

Yoichi M. A. Yamada,* Hiroshi Yoshida, Aya Ohno, Takuma Sato, Toshiaki Mase, and Yasuhiro Uozumi*

*Institute for Molecular Science (IMS), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan

Abstract

A copper-mediated Huisgen cycloaddition, aka the copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC), of flammable acetylene gas and a variety of organic azides proceeded smoothly by using our amphiphilic self-assembled polymeric copper catalyst MPPI-Cu to give the corresponding triazoles in high yield. MPPI-Cu was readily reused without loss of catalytic activity. The XAFS and DFT calculation studies revealed the local structure near Cu atom of an active species MPPI-Cu(I).

Supporting Info. (227KB)PDF (779KB)

Published online: 26th December, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13608
Molecular Structure and Spectroscopic Properties of [2,3,9,10,16,17,23,24-Octakis(3-carboxyphenoxy)phthalocyaninato-κ4N](pyridine-κN)zinc(II) Pyridine Octasolvate

Rei Fujishiro, Hayato Sonoyama, Yuki Ide, Shigeki Mori,* Tamotsu Sugimori, Atsushi Nagai, Katsumi Yoshino, Mikio Nakamura, and Takahisa Ikeue*

*Department of Chemistry, Graaduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan

Abstract

The title complex, [2,3,9,10,16,17,23,24-octakis(3-carboxyphenoxy)- phthalocyaninato-k 4N] (pyridine-kN)zinc(II) pyridine octasolvate abbreviated as [ZnPc(3-CO2H)8(Py)]ˑ8(Py) (2), has been obtained by recrystallization of [ZnPc(3-CO2H)8]·(1) from pyridine. Molecular structure of 2 determined by X-ray crystallography exhibits the anticipated N5 square pyramidal coordination structure around zinc(II) ion, where the average Zn-N(Pc) and Zn-N(Py) bond lengths are 2.027(4) Å and 2.121(4) Å, respectively. The deviation of the zinc(II) ion from the phthalocyanine N4 plane is 0.417 Å. Eight pyridine molecules are involved in the hydrogen bonding with the carboxylic acid moieties of phenoxy rings in a 1:1 mode. Two discrete phthalocyanine molecules in a unit cell are stacked in a back-to-back fashion with an interplanar distance of 3.376 Å. Pyridine solutions of 1 exhibit well-resolved 1H NMR, UV-Vis, and fluorescent spectra, suggesting that 1 exists as pyridine ligated monomeric species.

PDF (1.5MB)

Published online: 22nd December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)29
π-Expanded Cyclic Oligothiophehe 12-Mers as Semishape-Persistent Macrocycles

Mika Imamura, Hideyuki Shimizu, Jun Yamakawa, Hiroyuki Otani, Tohru Nishinaga, and Masahiko Iyoda*

*Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

Abstract

π-Expanded macrocyclic oligothiophene 12-mer E,E-12T10A, 18-mer E,E,E-18T15A, and 24-mer E,E,E,E-24T20A composed of thienylene, ethynylene, and vinylene moieties were synthesized in good total yield by the McMurry coupling reaction of dialdehyde 1. E,E-12T10A was converted to cyclo[12](3,4-dibutyl-2,5-thienylene-ethynylene) 12T12A in 20% yield by bromination-dehydrobromination procedure. Furthermore, the synthesis of 12T12A was carried out by using double elimination procedure starting from the sulfone dianion 22- and dialdehyde 1. The crystal structure of E,E-12T10A was determined by X-ray analysis. In the solid state, macrocyclic oligothiophenes formed nanostructured polymorphs such as single crystals, petal-shaped structure, and chained lumps depending on the ring size.

PDF (2.2MB)

Published online: 20th December, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13599
A new Isocoumarin Derivative from an Endophytic Fungus Thielavia sp. Isolated from Crassula ovata

Ken-ichi Nakashima,* Junko Tomida, Takao Hirai, Yuji Morita, Yoshiaki Kawamura, and Makoto Inoue

*Laboratory of Medicinal Resources, Faculty of Pharmaceutical Sciences, Aichi Gakuin University, 1-100 Kusumoto-cho Chikusa-ku Nagoya city 464-8650, Japan

Abstract

Thielavic acid (1), a new isocoumarin derivative, was isolated from an endophytic fungus Thielavia sp. ECN-115, which was obtained from the stems of Crassula ovata. The relative structure of 1 was established by spectroscopic analyses including extensive 2D-NMR experiments. The absolute configuration was identified as (4S)-thielavic acid by comparing the experimental and calculated electronic circular dichroism spectra.

PDF (1.1MB)

Published online: 19th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)59
Ni-Catalyzed Three-Component Coupling of 4-Methylene-2-oxazolidinones, Alkynes, and Trimethylaluminum

Tatsuya Yamahira, Ryo Ninokata, Gen Onodera, and Masanari Kimura*

*Graduate School of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

Ni(0) catalyzes the three-component coupling reactions of 4-methylene-2-oxazolidinones, alkynes, and trimethylaluminum accompanied by extrusion of carbon dioxide to furnish 2-methyl-3-amino-2,5-heptadiene with high regio- and stereoselectivities.

Supporting Info. (252KB)PDF (408KB)

Published online: 19th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)33
Syntheses of 2-Vinyl-2,3-dihydropyrroles and 3-Methylene-1,2,3,4-tetrahydropyridines by Palladium-Catalyzed Cyclization of N-Tosyl Imines with Allylic Diesters

Masahiro Yoshida,* Kouki Kinoshita, and Kosuke Namba

*Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Nishihama, Yamashiro-cho, Tokushima, 770-8514, Japan

Abstract

A palladium-catalyzed cyclization of N-tosyl imines with allylic diesters is described. The reactions of N-tosyl imines with 2-buten-1,4-diol dicarbonate and 2-methylene-1,3-propanediol diacetate afforded 2-vinyl-2,3-dihydropyrroles and 3-methylene-1,2,3,4-tetrahydropyridines, respectively.

PDF (561KB)

Published online: 19th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)32
Efficient Total Syntheses of Natural Neopterin Glycosides: Neopterin Glucronide and Solfapterin

Tadashi Hanaya,* Katsuya Iwasaki, Kaori Saeki, and Takafumi Hattori

*Department of Chemistry, Faculty of Science, Okayama University, Tsushima-naka, Okayama 700-8530, Japan

Abstract

1’,2’-Di-O-acetyl-N2-(N,N-dimethylaminomethylene)-3-[2-(4-nitro- phenyl)ethyl]neopterin (11a) and its 1’,2’-di-O-benzoyl analog (11b) were prepared from neopterin in 5 steps, respectively. Glycosylation of 11a with methyl 2,3,4-tri-O-benzoyl-α-D-glucopyranosyluronate bromide (15b) in the presence of silver triflate afforded the corresponding 3’-O-(β-D-gluco- pyranosyl)neopterin derivative (18) in 64% yield. The similar treatment of 11b with 2-azido-3,4,6-tri-O-benzoyl-2-deoxy-α-D-glucopyranosyl bromide (21b) provided the corresponding 3’-O-(α-D-glucopyranosyl)neopterin derivative (23a) in 58% yield. The first syntheses of neopterin glucronide (5) and solfapterin (6) were achieved by successive removal of the protecting groups of 18 and 23a, respectively.

PDF (695KB)

Published online: 19th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)40
Synthesis of Tricyclcic Dioxetanes That Exhibit Intramolecular Charge-Transfer-Induced Decomposition: Relationship between Structure and Chemiluminescence Efficiency

Nobuko Watanabe,* Yuukou Mizuno, Yoshinori Maeda, Hisako K. Ijuin, and Masakatsu Matsumoto*

*Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan

Abstract

Tricyclic dioxetanes bearing a 3-oxyphenyl group 35 were stereoselectively synthesized in high yields by the singlet oxygenation of three types of 5-(3-oxyphenyl)-2,3-dihydrofurans fused with a cyclopentane ring 6b8b. Upon treatment with tetrabutylammonium fluoride (TBAF) in DMSO or acetonitrile at 25 °C, these dioxetanes underwent charge-transfer-induced decomposition (CTID) accompanied by the emission of bright blue light. Although all of these dioxetanes gave excited oxyanions of 3-hydroxybenzoate as an emitter, their chemiluminescence efficiencies were significantly different and depended on their structures.

Supporting Info. (1.5MB)PDF (2.2MB)

Published online: 19th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)45
Stylissamide I, a New Cyclic Heptapeptide from an Okinawan Marine Sponge Stylissa sp.

Takaaki Kubota,* Kenta Nakamura, Shin-ichiro Kurimoto, Kanae Sakai, Jane Fromont, Tohru Gonoi, and Jun'ichi Kobayashi*

*Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan

Abstract

A new cyclic heptapeptide, stylissamide I (1), was isolated from an Okinawan marine sponge Stylissa sp. The structure of stylissamide I (1) was elucidated to be cyclo-(L-Tyr1-L-Tyr2-L-Tyr3-L-Pro1-L-Pro2-L-Val-L-Pro3) by extensive spectral analyses and Marfey’s method. Stylissamide I (1) showed antifungal activity against Aspergillus niger.

Supporting Info. (4.7MB)PDF (345KB)

Published online: 16th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)39
Rhodium(I)-Catalyzed Silylation of Aryl Iodides with Di(2-furyl)methylsilane

Yoshihito Kohari, Yusuke Kano, Yusuke Matsuoka, Takeshi Namikoshi, Shinji Watanabe, and Miki Murata*

*Department of Materials Science and Engineering, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507, Japan

Abstract

The efficient silylation of aryl iodides with di(2-furyl)methylsilane has been developed utilizing a rhodium catalyst. The substrate scope is broad and includes electron-rich and -deficient aryl iodides.

Supporting Info. (612KB)PDF (407KB)

Published online: 15th December, 2016

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)30
Structural Development Studies of Pyrazoloketone-Derived Acetyl-CoA Carboxylase Inhibitors

Shogo Okazaki, Taki Sakai, Minoru Ishikawa, Yuichi Hashimoto, and Takao Yamaguchi*

*Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan

Abstract

Acetyl-CoA carboxylase (ACC) plays a key role in fatty acid homeostasis in humans, and inhibitors of ACC are expected to inhibit fatty acid biosynthesis and to activate fatty acid β-oxidation. Therefore, they are considered to be candidates for treatment of metabolic syndrome and related diseases. In this context, an upstream kinase of ACC, adenosine monophosphate-activated protein kinase (AMPK), has also recently emerged as a potential therapeutic target, because it phosphorylates and inactivates ACC. Here, we designed a fused molecule consisting of a pyrazoloketone-type ACC inhibitor and a recently discovered AMPK activator, aiming to develop a novel combined ACC inhibitor/AMPK activator to regulate fatty acid levels. The designed compound was prepared through a convergent synthetic route. This compound and its methyl ester analogue showed potent ACC2-inhibitory activity with IC50 values of 8.8 and 1.3 μM, respectively. Exomethylene derivatives, obtained from an unexpected side reaction during deprotection, also exhibited ACC2-inhibitory activity.

PDF (1.3MB)

Published online: 15th December, 2016

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)48
Synthesis of 2-Arylamino-1-azaazulenes

Satoru Tsukada,* Makoto Nakazawa, Yuya Okada, Keito Ohtsu, Noritaka Abe, and Takahiro Gunji

*Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan

Abstract

A series of 2-arylamino-1-azaazulenes were synthesized by the Buchwald-Hartwig cross coupling reaction. The resulting compounds were characterized by 1H NMR, 13C NMR, HRMS analyses, and elemental analysis. X-Ray crystallographic analysis revealed that 2-(1-naphthylamino)-1-azaazulene exists in dimeric form with two intermolecular N–HN hydrogen bonds in its crystal structure.

PDF (12.5MB)

Published online: 14th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)64
Kinetic Switching of Achirality/Chirality Memorization of Meta-Ethynylpyridine Polymer by Coordination of Cu(II) Outside the Polymer

Hajime Abe,* Shunsuke Takashima, and Masahiko Inouye*

*Graduate School of Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan

Abstract

Memorization of achirality and chirality of meta-ethynylpyridine polymer with amino side chains was actualized by cross-linking with Cu(OTf)2 as a precursor. When β-D-glucopyranoside and Cu(OTf)2 were added to the coordinative polymer in this order, a CD band was induced around 340 nm and enhanced by Cu(II)-coordination. On the other hand, in the case Cu(OTf)2 and β-D-glucopyranoside were added to the polymer in this order, only a weak CD band was induced because achirality was memorized before the addition of the glucoside. For the chiral helical complex with enhanced CD, a chiral memorization effect was assured by the addition of β-L-glucopyranoside causing very slow decay of the CD band.

PDF (577KB)

Published online: 13th December, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)47
Gold(III)-Catalyzed Synthesis of 2,3,4-Trisubstituted Dihydropyrans from Propargylic Alcohols with 1,3-Dicarbonyl Compounds

Nobuyoshi Morita,* Kazuki Oguro, Saori Takahashi, Midori Kawahara, Shintaro Ban, Yoshimitsu Hashimoto, and Osamu Tamura*

*Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan

Abstract

2,3,4-Trisubstituted dihydropyrans were efficiently synthesized by tandem reaction of propargylic alcohols with 1,3-dicarbonyl compounds in the presence of 5 mol% gold(III) catalyst (dichloro[2-pyridinecarboxylato]gold) and 10 mol% silver catalyst (AgNTf2).

Supporting Info. (1.4MB)PDF (522KB)

Published online: 13th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)58
A Remarkably Useful Sulfur Bridge as Synthetic Lever in an Approach to Javanicin B

Amélie Dion and Claude Spino*

*Université de Sherbrooke, Département de chimie, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada

Abstract

A concise and efficient synthesis of a non-racemic advanced intermediate to the quassinoid javanicin B is disclosed. The strategy is centred on a triple diene-transmissive Diels-Alder cycloaddition to form the four rings of javanicin B. A sulfur bridge plays several crucial roles allowing an intramolecular cycloaddition to occur with complete stereoselectivity, controlling the stereochemical outcome of another cycloaddition, and transforming into a pivotal electrophile for the introduction of a particularly hindered methyl group.

Supporting Info. (772KB)PDF (780KB)

Published online: 13th December, 2016

Review | Regular issue | Prepress
DOI: 10.3987/REV-16-846
1,2,3-Benzotriazin-4(3H)-ones: Synthesis, Reactions and Applications

Zunera Khalid, Hafiz Adnan Ahmad, Munawar Ali Munawar,* Misbah-ul-Ain Khan, and Salman Gul

*Institute of Chemistry, University of the Punjab, Lahore 54590, Pakistan

Abstract

An up-to-date review of 1,2,3-benzotriazin-4(3H)-ones including its synthesis, reactions and applications is presented. The title ring system deserves a special treatment due to its increasing importance in pharmaceuticals, imaging and recording materials.

PDF (4.9MB)

Published online: 12th December, 2016

Communication | Regular issue | Prepress
DOI: 10.3987/COM-16-13602
Enantioselective Protecting-Group-Free Synthesis of (+)-9,10-Dihydroecklonialactone B

Asmaa Said Ali Yassen, Jun Ishihara, and Susumi Hatakeyama*

*Medical Innovation Center, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

An enantioselective protecting-group-free route to ecklonialactones, C-18 oxylipins isolated from the brown algae, was demonstrated by the synthesis of (+)-dihydroecklonialactone B from (E)-ethyl hex-3-enoate in 17 steps.

PDF (235KB)

Published online: 9th December, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13595
Facile and Convenient Syntheses of Fluorine-Containing Pyrimido[5,4-c]quinolines and Benzo[h][1,6]naphthyridines by Condensation Reaction of 2-Methoxy-3-trifluoroacetyl-4-quinolylamine with Aldehydes and Ketones

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-Methoxy-3-trifluoroacetyl-4-quinolylamine reacted easily with various aldehydes in the presence of aqueous ammonia to afford mainly trifluoromethylated pyrimido[5,4-c]quinoline derivatives in moderate to high yields. In contrast, the use of ketones instead of aldehydes in the presence of pyrrolidine, exclusively gave benzo[h][1,6]naphthyridine derivatives in good to excellent yields.

PDF (1.5MB)

Published online: 8th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)53
Nucleophilic Substitution Reactions on Indole Nucleus: Formation of (3a,8a-cis)-1,2,3,3a,8,8a-Hexahydropyrrolo[2,3-b]Indoles Having A Substituent at the 3a-Position

Fumio Yamada, Aya Goto, Masakazu Hasegawa, Kensuke Kobayashi, and Masanori Somei*

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

Abstract

Various nucleophiles, such as indole, 1,2,3-trimethoxybenzene, anisole, phenol, and pyrrole, reacted with 1-hydroxy-Nb-trifluoroacetyltryptamine under the presence of mesyl chloride to give novel series of (3a,8a-cis)-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indoles having a substituent at the 3a-position. Their structures and by-products were strictly determined.

PDF (759KB)

Published online: 8th December, 2016

Review | Special issue | Prepress
DOI: 10.3987/REV-16-SR(S)2
Strategies for Brevisamide Synthesis, Based on the Method for Constructing the Tetrahydropyranyl Core

Takeo Sakai and Yuji Mori*

*Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tenpaku, Nagoya 468-8503, Japan

Abstract

Brevisamide is a monocyclic ether alkaloid produced by the red tide dinoflagellate Karenia brevis. Brevisamide has attracted the attention of organic chemists because it is the smallest molecule that can be used to understand the biosynthetic 6-endo epoxide cyclization of polycyclic ethers. Within nine years of its discovery, several diverse approaches to synthesizing this monocyclic ether amide have been explored, culminating in the publication of eight total and seven formal total syntheses. In the first part of this review, we discuss strategies for the introduction of the key elements—the (2E,4E)-3,4-dimethyl-2,4-heptadienal side chain, acetamide side chain, C9 axial methyl group, and tetrahydropyran (THP) core. In the following sections, each of the total and formal syntheses is overviewed, based on the method for constructing the THP core.

PDF (3.2MB)
113 data found. 1 - 30 listed Next Last