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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.

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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.

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Published online: 7th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)37
Synthesis of Photophore and Fluorophore Modified O-Benzylserine Derivatives

Makoto Hashimoto,* Takuma Yoshida, Zetryana Puteri Tachrim, Yasuko Sakihama, Yasuyuki Hashidoko, Yasumaru Hatanaka, and Yuichi Kanaoka

*Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan

Abstract

O-Benzylation of serine is one of the important protection methods for solid phase peptide synthesis. The utilities of the protection group may be indicated that chemical modifications for O-benzylserine will be utilized to make functional peptides on solid phase synthesis. Detailed studies for effective synthesis of photoreactive and fluorophore containing O-benzylserine derivatives without racemization were reported.

Supporting Info. (1.7MB)PDF (559KB)

Published online: 5th December, 2016

Review | Special issue | Prepress
DOI: 10.3987/REV-16-SR(S)3
Total Synthesis of (+)-Linoxepin

Minami Odagi,* Kota Furukori, Yoshiharu Yamamoto, and Kazuo Nagasawa*

*Department of Biotechnology and Life Science, Faculty of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan

Abstract

(+)–Linoxepin is a lignan-type natural product with a synthetically challenging fused dihydronaphthalene/dihydroxepine structure. It also has multiple biological activities, including antitumor, antioxidant, and antiviral activities. Here, we review three recent total syntheses of (+)–linoxepin.

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Published online: 5th December, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)56
Catalytic and Enantioselective Diels-Alder Reaction of Silyloxydiene That Incorporates a Pyrrolidine Ring, and Its Application to the Construction of Chiral Tri- and Tetracyclic Skeletons

Shinji Harada, Saki Nakashima, Wataru Yamada, Takahiro Morikawa, and Atsushi Nishida*

*Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, Japan

Abstract

The enantioselective Diels-Alder reaction of silyloxydiene that incorporates a pyrrolidine ring was studied. This reaction was catalyzed by a chiral holmium complex and gave multi-substituted chiral hydroindoles that contained a silyl enol ether, which is a key functional group for further transformations. We demonstrate here the synthesis of chiral pyrroloacridine, dibenzodiazocine, and pyrrolocarbazole skeletons.

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Published online: 2nd December, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13606
One-Pot Palladium-Catalyzed Racemization of (S)-Praziquanamine: A Key Intermediate for the Anthelmintic Agent (R)-Praziquantel

Zhezhou Yang, Xiang Guo, Shanghu Xu, Huirong Jiao, Zhinmin Tan, and Fuli Zhang*

*Shanghai Institute of Pharmaceutical Industry, China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai 201203, China

Abstract

An one-pot palladium-catalyzed procedure for racemization of (S)-praziquanamine, which is the undesired enantiomer and produced during the resolution step for preparing the anthelmintic drug (R)-praziquantel, has been developed through dehydrogenation of (S)-praziquanamine into 6,7-dihydro-4H-pyrazino[2,1-a]isoquinolin-4-one and then hydrogenation of the double bonds. And a superior racemization method was also developed that (S)-praziquanamine was directly treated with Pd/C under H2 atmosphere to obtain a racemic mixture in quantitative yield with 95% chemical purity. Such a concise and efficient approach to the racemization of (S)-praziquanamine can be useful to recycle the waste enantiomer into the resolution process to obtain the (R)-enantiomer on a large scale.

Supporting Info. (1.5MB)PDF (1.1MB)

Published online: 1st December, 2016

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)35
2-Arylquinoline Synthesis from Cbz-Protected 2-Aminochalcone Mediated by BF3•Et2O

Tomohiro Maegawa,* Misa Nogata, Takaya Honda, Akira Nakamura, and Yasuyoshi Miki*

*School of Pharmaceutical Sciences, Kindai University, 3-4-1, Kowakae, Higashi-Osaka 577-8502, Japan

Abstract

A novel approach to producing the quinoline skeleton from 2-aminochalcone was developed. Treatment of benzyloxycarbonyl (Cbz)-protected 2-aminochalcones with BF3·Et2O afforded quinoline derivatives via the deprotection of the Cbz group and isomerization of olefin in a one-pot reaction. The reaction of various 2-aminochalcones proceeded to give the corresponding 2-arylquinoline derivatives in good yields. This method is applicable to the rapid synthesis of dubamine.

Supporting Info. (1.6MB)PDF (484KB)

Published online: 29th November, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)60
Simultaneous Functionalization and Cyclization of 2-Ethynylaniline Derivatives to Indoles

Kou Hiroya,* Shin Itoh, Kiyofumi Inamoto, Hiroki Shigehisa, and Takao Sakamoto

*Faculty of Pharmacy, Musashino University, 1-1-20 Shin-machi, Nishitokyo-shi, Tokyo, Japan

Abstract

Two different kind of sequential cyclization-functionalization are developed. Namely, cyclization-chlorination of 2-ethynylaniline derivatives using CuCl2 gave 3-chloro- and 3,5-dichloroindole derivatives. The plausible mechanism for this reaction is also discussed. On the other hand, the reaction between 2-ethynylaniline derivatives and Cu(NO3)2·3H2O in THF provided C4-nitro compound. After being changed the solvent from THF to DMF, followed by heating, 5-nitroindole derivatives was afforded.

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Published online: 28th November, 2016

Communication | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)46
Efficient D-Fructopyranosylation Method Catalyzed by Scandium Triflate and Preparation of New Sucrose Analogs

Takashi Yamanoi,* Takanori Saitoh, Yoshiki Oda, Noriko Misawa, Mikio Watanabe, Junko Ishikawa, and Akihiko Koizumi

*Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan

Abstract

We successfully established a highly efficient β-fructopyranosylation method that used a fully benzoylated β-D-fructopyranosyl acetate as the glycosyl donor and Sc(OTf)3 as the catalytic activator. The syntheses of non-reducing disaccharide units as new sucrose analogs were achieved based on the β-fructopyranosylation reaction of 1-hydroxy group of glucose derivatives.

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Published online: 28th November, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)68
An Enantioselective Synthesis of 2-Imidazolidinones through Bifunctional Thiourea-Catalyzed Tandem Mannich/Cyclization of Isocyanatomalonate Diester

Yusuke Kobayashi, Takuma Yoshida, Takuya Uno, Chihiro Tsukano, and Yoshiji Takemoto*

*Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-shimoadachi-machi, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

A chiral bifunctional thiourea-catalyzed Mannich reaction of diethyl 2-isocyanatomalonate with N-sulfonylimines was described. The tandem cyclization proceeded smoothly after Mannch reaction, directly furnishing chiral 2-imidazolidinones in 72‒99% yields with 83‒98% ees. Sterically demanding sulfonyl group was crucial for aliphatic imines to afford the corresponding product in high enantioselectivity.

Supporting Info. (530KB)PDF (561KB)

Published online: 25th November, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)52
Synthesis of Multi-Substituted 1,4-Benzoxazine Using an Umpolung Reaction with 2-Oxo-1,4-benzoxazine-3-carboxylates

Takanori Tanaka, Isao Mizota, Kazuto Umezu, Akinori Ito, and Makoto Shimizu*

*Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-cho Tsu, Mie 514-8507, Japan

Abstract

This report describes a one-pot synthesis of multi-substituted 1,4-benzoxazine derivatives by atom economical N,C-dialkylation reaction of 1,4-benzoxazine derivatives with various organozinc reagents and ketene silyl acetals (KSA).

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Published online: 22nd November, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)54
Synthesis of Benzyl Tetra-O-acetyl-α-L-glucopyrnoside from Benzyl 2,3-Dideoxy-β-D-erythro-hex-2-enopyranoside

Hayato Okazaki, Yuji Ueda, Kengo Hanaya, Mitsuru Shoji, and Takeshi Sugai*

*Department of Pharmaceutical Science, Keio University, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512, Japan

Abstract

Benzyl tetra-O-acetyl-α-L-glucopyranoside was synthesized from benzyl 2,3-dideoxy-β-D-erythro-hex-2-enopyranoside in six steps and 19% overall yield. Epoxidation from the β-side of the double bond between C-2 and C-3 of the starting material along with the subsequent regioselective ring opening by the backside attack of a hydroxide ion at C-3 furnished an intermediate with D-ido-stereochemistry. The inversion at C-5 was performed by an epimerization, by way of an N-cyclohexylenamine, after the chemoselective oxidation at primary hydroxy group of the C-6 to an aldehyde. The present synthesis of L-glucose derivatives implies the sequential stereochemical inversion of C-2 to C-5 of D-glucose. As the present synthesis keeps the whole skeleton and the order of carbon atoms based on the original numbering of D-glucose, it would work well for the synthesis of specifically labeled derivatives, beginning from isotopically labeled D-glucoses.

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Published online: 18th November, 2016

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)74
Synthesis of a Functionalized Morphan Scaffold via a Palladium-Catalyzed Cycloalkenylation and Beckmann Rearrangement

Natsuko Kagawa, Yutaka Yamamoto, Shuichiro Ono, and Masahiro Toyota*

*Department of Chemistry, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuencho, Sakai, Osaka 599-8531, Japan

Abstract

Functionalized 2-azabicyclo[3.3.1]nonan-3-ones, potential precursors to morphan, were assembled using a combination of a palladium-catalyzed cycloalkenylation and a Beckmann rearrangement.

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Published online: 16th November, 2016

Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13584
Synthesis of β-Glycosyl Formamides Through N-Glycosylation of Unprotected Carbohydrates

Yoshiyasu Ichikawa,* Akihito Matsukawa, Mitsutoshi Maeda, Yumiko Tomita, Rika Mimura, Ayumi Kitamori, Hiyoshizo Kotsuki, Keiji Nakano, and Toshiya Masuda

*Faculty of Science, Kochi University, 2-5-1, Akebono-cho, Kochi 780-8520, Japan

Abstract

Two new synthetic routes involving N-glycosylation of unprotected carbohydrates were developed for the preparation of β-glycosyl formamides. Using this protocol, D-glucose, D-xylose, D-galactose and D-maltose were transformed to their corresponding β-glycosyl formamides.

Supporting Info. (1.4MB)PDF (487KB)

Published online: 11th November, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)25
Synthesis and Electrochemical Properties of Azulene-Substituted Tetracyanobutadiene and Dicyanoquinodimethane Chromophores Connected with Naphthalene Cores

Taku Shoji,* Mitsuhisa Maruyama, Akifumi Maruyama, Daichi Nagai, Miwa Tanaka, Ryuta Sekiguchi, Shunji Ito, and Tetsuo Okujima

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

Abstract

Azulene-substituted tetracyanobutadienes (AzTCBDs) and dicyanoquinodimethanes (AzDCNQs) connected with naphthalene cores were prepared by the reaction of 1-azulenylalkynes with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) in a formal [2 + 2] cycloaddition–retroelectrocyclization. The characteristic intramolecular charge transfer (ICT) characters were investigated by using UV/Vis spectroscopy and theoretical calculation. The redox behaviors of AzTCBDs and AzDCNQs were examined by cyclic voltammetry and differential pulse voltammetry, which revealed their properties of multi-electron transfer depending on the number of AzTCBD and AzDCNQ moieties. Moreover, significant color changes were observed by visible spectroscopy under the electrochemical reduction conditions.

Supporting Info. (10.6MB)PDF (1.6MB)

Published online: 11th November, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13567
An Efficient Synthesis of Functionalized Chromeno[4,3-d]pyrazolo[3,4-b]pyridine Derivatives

Wei Lin,* Yongxiang Zheng, Yazhen Wang, and Daqing Shi*

*College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China

Abstract

A series of functionalized chromeno[4,3-d]pyrazolo[3,4-b]pyridine derivatives were synthesized via one-pot three-component reaction of salicylaldehydes, 4-hydroxy-6-methyl-2H-pyran-2-one and pyrazol-5-amines catalyzed by CuSO4 in ethanol. The structures of all synthesized were identified by their IR, 1H NMR, 13C NMR and HRMS analysis, and the structure of compound 4h was confirmed by X-ray diffraction analyses.

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Published online: 11th November, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13574
One-Pot Regioselective Synthesis of Diazaspiro[5.5]undecane-1,5-dione-9-thione Derivatives Catalyzed by Reusable 1-Methylimidazolium Trifluoromethylsulfonate under Solvent-Free Conditions

Zhaohui Xu,* Houfu Zhang, Yunkui Xiong, Deyong Liu, and Qingshui Huang*

*College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang, Jiangxi 330027, China

Abstract

A green and environmentally benign Biginelli-like synthesis of 2,4-dioxa-8,10-diazaspiro[5.5]undecane-1,5-dione-9-thione derivatives by one-pot three-component reaction of aromatic aldehydes with thiourea and 1,3-dioxane-4,6-dione catalyzed by reusable 1-methylimidazolium trifluoromethylsulfonate under solvent-free conditions is described.

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Published online: 11th November, 2016

Communication | Regular issue | Prepress
DOI: 10.3987/COM-16-13590
A Facile One-Pot Synthesis of Chromeno[4,3-b][1,5]-Naphthyridines

Dong Wang, Dao-Lin Wang,* Xiao-Ce Shi, and Jian-Hua Qian

*Liaoning Key Laboratory of Synthesis and Application of Functional Compound, College of Chemistry & Chemical Engineering, Bohai University, Jinzhou 121001, China

Abstract

A simple and efficient synthesis of chromeno[4,3-b][1,5]naphthyridine derivatives were accomplished in high yields via the one-pot three-component reaction of 4-hydroxycoumarin, arylaldehyde and 3-aminopyridine in aqueous media catalyzed by sulfamic acid.

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Published online: 10th November, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)23
Efficient Synthesis of Fluorine-Containing Dibenzo[b,h][1,6]naphthyridines and Thiochromeno[3,2-c]quinolines Using Highly Chemoselective Nucleophilic Substitution Reaction of 4-Dimethylamino-2-methoxy-3-trifluoroacetylquinoline

Etsuji Okada,* Mizuki Hatakenaka, Yoshinori Takezawa, and Keisuke Iwakuni

*Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

Aromatic nucleophilic substitution reaction of N,N-dimethyl-2-methoxy-3-trifluoroacetyl-4-quinolylamine with various nucleophiles (NuH) such as amines, thiols, and alcohols proceeded chemoselectively at the 4-position to give the corresponding Me2N-Nu exchanged products. Novel fluorine-containing 6-methoxydibenzo[b,h][1,6]naphthyridines (11) and 6-methoxythiochromeno[3,2-c]quinolines (12) were synthesized in moderate to high yields by the trifluoromethanesulfonic acid catalyzed cyclization of thus obtained N-aryl-2-methoxy-3-trifluoroacetyl-4-quinolylamines (8) and aryl 2-methoxy-3-trifluoroacetyl-4-quinolyl sulfides (9), respectively.

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Published online: 10th November, 2016

Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13570
Strategic and Tactical Approaches to the Synthesis of 5,6-Dihydro-[1,2,4]oxadiazines

Johan J. N. Veerman,* Yorik B. Bruseker, Bart C. J. van Esseveldt, Rebecca Glen, Bryce A. Harrison, Erik H. Heijne, Andrew J. McRiner, Tommi M. Meulemans, Peter van Rijnsbergen, Wim Zonneveld, Matthew G. Bursavich,* and Duane A. Burnett

*Department of Chemistry, Mercachem B.V., Kerkenbos, 1013, Nijmegen 6546BB, Netherlands

Abstract

Three methods were developed for the synthesis of substituted 5,6-dihydro-4H-[1,2,4]oxadiazines. The desired oxadiazine rings were synthesised via reductive amination, addition to an iminium ion intermediate and by condensation of a diamine with an imidate. For all methods the scope with respect to the substituents that could be introduced was explored. It was found that the imidate condensation route was the most versatile and the products could be isolated in yields up to 91%. This route is also suitable for the introduction of chirality on the C5 and C6 position of the oxadiazine rings.

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Published online: 10th November, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13573
Methodology to Access Thiazo[3’,2’:2,3]pyrido[4,5-d]thiazolo[3,2-a]pyrimidinones

Dao-Lin Wang,* Dong Wang, Qiao-Min Li, and Jian-Hua Qian

*Liaoning Key Laboratory of Synthesis and Application of Functional Compound, College of Chemistry & Chemical Engineering, Bohai University, Jinzhou 121001, China

Abstract

A synthesis of model thiazolo[3’,2’:2,3]pyrido[4,5-d]thiazolo[3,2-a] pyrimidin-5-ones (5), based on the classical Pictet-Spengler method, is described. The key intermediate, 7-(3-amino-5-phenylaminothiazol-2-yl)-5H-thiazolo [3,2-a]pyrimidin-5-one (3), was synthesized from 7-chloromethyl-5H-thiazolo [3,2-a]pyrimidin-5-one (1) with potassium N-phenyl-N'-cyanoimidothiocarbonate (2) by Thorpe-Ziegler isomerization. Cyclocondensation of the intermediate amine with aromatic aldehydes, using sulfamic acid under Pictet-Spengler reaction conditions, delivered the target compounds 5a-m

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Published online: 9th November, 2016

Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13558
Design, Synthesis, in vitro Antiproliferative Activity Evaluation of 2-Acylaminothiopene-3-carboxamide Derivatives

Jiefeng Zhang, Fengjie Guan, Jiakun Qiu, Yanfen Fang, Lifang Yu, Jingya Li, Fan Yang, Xiongwen Zhang, Jia Li, and Jie Tang*

*Department of Chemistry, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China

Abstract

A series of 2-alkanoylamidothiophene-3-carboxamide derivatives were synthesized based on the hit compound 1. The anti-proliferative activity of all the compounds in vitro against MGC-803 (stomach) and HCT-116 (colon) cancer cell lines using SRB assays were tested. Several compounds showed improved anti-proliferative activity against MGC-803 and HCT-116. SAR study revealed that chlorine substituent in the 2-acetylamino part was important for anti-proliferative activity. 5a, 11b, 11c and 11d were the most potent compounds against MGC-803 (IC50s = 2.32-2.95 μM), and 5a and 11c also showed good anti-proliferative activity against HCT-116 cells (IC50s = 3.41-3.75 μM). In addition, the anti-proliferative activity of 11b and 11d could be attributed to the apoptosis in HCT116 cells via caspase 3 activation, confirmed by flow cytometry assay and western blot analysis. Meanwhile, 11b and 11d decreased the mitochondrial membrane potential (MMP) in HCT116 cells.

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Published online: 9th November, 2016

Review | Regular issue | Prepress
DOI: 10.3987/REV-16-848
Dipolar Cycloadditions of Nitrones in Aqueous Media

Giorgio Molteni*

*Department of Organic and Industrial Chemistry, University of Milano, Via Golgi 19, 20133 Milano, Italy

Abstract

1,3-Dipolar cycloadditions of nitrones in aqueous media have been recently exploited as a non-conventional protocol in the synthesis of the fully- or partly-saturated isoxazole ring. Water as the reaction medium can affect positively both cycloaddition rates and yields, while the large array of latent functionalities displayed by the cycloadducts is of interest in their further transformations. A systematic review of literature data is given; improvements with respect to the nitrone cycloaddition carried out in organic solvents will be taken into account.

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Published online: 8th November, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13566
An Efficient Synthesis of 3-(Arylsulfanyl)quinolin-4(1H)-ones via Cyclization of N-{2-[2-(Arylsulfanyl)acetyl]phenyl}benzamides with N,N-Dimethylformamide Dimethyl Acetal

Kazuhiro Kobayashi,* Kohei Nishikawa, and Takashi Nogi

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

Abstract

The reaction of N-[2-(2-chloroacetyl)phenyl]benzamides, readily derived from 2-(2,2-dichloroethenyl)benzenamines, with sodium arenethiolates gives the corresponding N-{2-[2-(arylsulfanyl)acetyl]phenyl}benzamides. These are treated with N,N-dimethylformaide dimethyl acetal (DMF–DMA) to yield 3-(arylsulfanyl)quinolin-4(1H)-ones in generally good yields.

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Published online: 8th November, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13592
Regioselective Bromination of 2-Iodomethyl-2,3-Dihydrothiazolo[3,2-a]pyrimidin-5-one

Renata Studzińska,* Renata Kołodziejska, Tomasz Kosmalski, and Bożena Modzelewska-Banachiewicz

*Department of Organic Chemistry, Nicolaus Copernicus University, Collegium Medicum in Bydgoszcz, Jurasza 2, Bydgoszcz 85-089, Poland

Abstract

The bromination reactions of 2-iodomethyl-2,3- dihydrothiazolo[3,2-a]pyrimidin-5-one were carried out using bromine and NBS as the brominating agent. Depending on the brominating agent used and a solvent two bromo derivatives were obtained: the product of electrophilic substitution in the pyrimidin ring and the product containing two bromine atoms which was formed as a result of two parallel reactions – an electrophilic substitution on the pyrimidine ring and a nucleophilic substitution of iodine. The position of bromine atoms in the obtained compounds was confirmed using 1H NMR spectrum.

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Published online: 7th November, 2016

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)44
Syntheses of Partially Brominated Derivatives of Tetra-2-thienylmethane for Three-Dimensionally Extended π-Electron Systems

Kouzou Matsumoto,* Takeshi Suzuki, Yasukazu Hirao, Hiroyuki Kurata, and Takashi Kubo*

*Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-8531, Japan

Abstract

Partially α-brominated derivatives of tetra-2-thienylmethane (Brn-TTM; n = 1–3) were synthesized and isolated in gram quantities. An alternative and more selective preparation of Br3-TTM was also developed. A new π-electron system based on the tetra-2-thienylmethane framework was synthesized from the monobromo derivative of tetra-2-thienylmethane.

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Published online: 7th November, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13564
Synthesis of Quinoline Derivatives by an Improved Döebner-von Miller Reaction Using a Recyclable Ag(I)-Exchanged Montmorillonite K10 Catalyst

Janeeka Jayram and Vineet Jeena*

*School of Chemistry and Physics, University of KwaZulu-Natal, Cnr Golf and Ridge Roads 3209, South Africa

Abstract

The Döebner-von Miller synthesis of quinolines under solvent-free conditions is described, catalyzed by recyclable Ag(I)-exchanged Montmorillonite K10. The desired products are obtained in good to excellent yields and the reaction accommodates both aromatic and aliphatic α,β-unsaturated aldehydes making this process an attractive method for the synthesis of substituted quinolines. In addition, the Ag(I)-exchanged Montmorillonite K10 catalyst can be recovered and reused up to 5 times with excellent activity.

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Published online: 4th November, 2016

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-16-13579
Synthesis of 1-Aryl-1,3-dihydrobenzo[c]thiophenes by Acid-Mediated Cyclization of 1-[Aryl(methoxy)methyl]-2-[(tert-butylsulfanyl)methyl]benzenes

Kazuhiro Kobayashi* and Yuuho Shigemura

*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 preparation of 1-aryl-1,3-dihydrobenzo[c]thiophenes has been developed using a three-step sequence starting from 2-[aryl(methoxy)methyl]benzyl alcohols. Thus, treatment of the starting materials with thionyl chloride gives the corresponding benzyl chlorides, which are allowed to react with sodium tert-butyl mercaptide to yield 1-[aryl(methoxy)methyl]-2-[(tert-butylsulfanyl)methyl]benzenes. Finally, these compounds undergo cyclization on treatment with concentrated hydrobromic acid to provide the desired products in reasonable yields.

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Published online: 1st November, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)42
Triphosgene-Mediated Chlorolactamization and Aminolactamization of Homoallylic Amines

Yuika Nishida, Norihiko Takeda, Okiko Miyata,* and Masafumi Ueda*

*Department of Medicinal Chemistry, Kobe Pharmaceutical University, 4-19-1, Motoyamakitamachi, Higashinada, Kobe 658-8558, Japan

Abstract

Two types of aminocarbonylation reaction of homoallylic amines have been developed. The treatment of homoallylic amines with triphosgene in dichloromethane led to formation of the corresponding β-chlorolactams via Prins-type cyclization of a carbamoyl chloride intermediate. For the reaction in acetonitrile, β-aminolactams were obtained via sequential Prins-type cyclization and Ritter-type reactions.

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Published online: 31st October, 2016

Paper | Special issue | Prepress
DOI: 10.3987/COM-16-S(S)28
Preparation of (R)-3-Hydroxy-N-methylpiperidine, a Synthetic Key Intermediate of (R)-Mepenzolate, Based on the Lipase-Catalyzed Resolution of the Racemic Form

Yasunobu Yamashita, Kengo Hanaya, Mitsuru Shoji, and Takeshi Sugai*

*Department of Pharmaceutical Science, Keio University, 1-5-30, Shibakoen, Minato-ku, Tokyo 105-8512, Japan

Abstract

In this study, a two-step method for the gram-scale synthesis of (R)-3-hydroxy-N-methylpiperidine in 97.8% enantiomeric excess (ee) is reported. The key chiral synthetic intermediate of (R)-mepenzolate was formed in 22% yield over two steps using a commercially available and inexpensive racemic alcohol as the starting material. In the first step, Candida antarctica lipase B-catalyzed kinetic resolution of the racemic alcohol under acetylation conditions was performed to obtain the acetate form of the (R)-enantiomer in 82.1% ee (E 18). The second step involved enantio-enrichment using the same lipase to catalyze deacetylation. The ee of the product (R)-alcohol was further enriched to 97.8%.

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