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Published online: 19th November, 2018

Communication | Regular issue | Prepress
DOI: 10.3987/COM-18-13988
■ New Facile Synthesis of 3-Substituted 7,8-Dihydroquinolin-5(6H)-ones and [1]Benzopyrano[4,3-b]pyridin-5-ones Using 2-(Hetero)aryl-vinamidinium Salts

Yiyi Weng, Chen Sun, Qingwei Cao, Hantao Chen, Nanhui Li, Zhuo Chen, and Weike Su*

*Collaborative Innovation Center of Yangtze River Delta Region Green of Pharmaceuticals, Zhejiang University of Technology, Hangzhou 310014, China

Abstract

The method of cyclocondensation of 3-amino-2-cyclohexen-1-ones 2 or 4-aminocoumarin 3 with symmetrical 2-(hetero)aryl-vinamidinium salts 1 has been developed, providing an efficient synthetic pathway to access novel functionalized 3-substituted 7,8-dihydroquinolin-5(6H)-ones 4 or [1]benzopyrano[4,3-b]pyridin-5-ones 5 in good to excellent yields. All the aryl-substituted and heterocyclic-substituted vinamidinium salts undergo a facile electrocyclic ring closure to form pyridine ring with α,β-unsaturated ketones. A possible mechanism for the formation of pyridine ring is proposed.

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Published online: 16th November, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)54
■ Bimetallic Lewis Acid Template-Mediated Enantioselective Hetero-Diels-Alder Reactions of 4-Siloxy-2,4-pentadienols

Jun Ishihara,* Yuka Ohzono, Kengo Oka, Yasuhiro Urayama, and Susumi Hatakeyama

*Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8521, Japan

Abstract

Enantioselective hetero-Diels-Alder reactions catalyzed by a bimetallic Lewis acid template are described. The hetero-Diels-Alder reactions of 4-siloxy-2,4-pentadienols and various dienophiles by the chiral H8-BINOL template provide a general entry into the substituted dihydropyrans with good enantioselectivities. This protocol is also applicable to a dihydropirazine formation.

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Published online: 15th November, 2018

Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13969
■ Synthesis, Characterization and Antimicrobial Evaluation of Some Novel Fused Pyrimido[1,2-b][1,2,4]triazine, Triazino[2,3-a]quinazoline and Imidazo[1,2-b][1,2,4]triazine Derivatives

Khaled S. Mohamed* and Elsherbiny H. El-Sayed

*Engineering Chemistry Department, Higher Institute for Engineering and Technology, New Damietta, Egypt

Abstract

A novel pyrimido[1,2-b][1,2,4]triazine derivatives were synthesized by allowing 3-amino-1,2,4-triazine (1) to react with different reagents such as enaminone, enaminonitriles, 3-bromopropanenitile, 2-(2,5-dimethoxybenzylidene)malononitrile and 1,3-dicarbonyl compounds. Moreover, triazino[2,3-a]quinazoline derivatives were synthesized by reaction of 1 with 2-((dimethylamino)methylene)-5,5-dimethylcyclohexane-1,3-dione (18) and 2,6-bis(pyridin-3-ylmethylene)cyclohexan-1-one (20). On the other hand, treatment of 1 with 2-bromo-1-(naphtho[2,1-b]furan-2-yl)ethan-1-one (22) afforded imidazo[1,2-b][1,2,4]triazine derivative (23). The newly synthesized compounds were evaluated for their antimicrobial activities based on inhibition diameter zone against Gram positive and Gram negative bacteria.

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Published online: 15th November, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13991
■ A Pair of New Non-Glycosidic Iridoid Epimers from Scrophularia ningpoensis

Wei Zhang, Peng Liu, Xin-Yu Ji, Xiang-Yang Chen, Yan-Yan Jiang, and Bin Liu*

*School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China

Abstract

A pair of new non-glycosidic iridoid epimers, ningpogenins A and B (1a/1b), together with eighteen known ones (2-19) were isolated from the roots of Scrophularia ningpoensis. Their structures were elucidated by spectroscopic analyses, including 1D-, 2D-NMR, and HR-ESI-MS. Compound 1 is an unusual example of natural ningpogenin—L-pyroglutamic adducts. In addition, the cytotoxic effects of the new compound against HepG2, U251 and SH-SY5Y cell lines were evaluated.

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Published online: 14th November, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)48
■ One-Step Synthesis of 4H-3,1-Benzoxazin-4-ones from Weinreb Amides and 1,4,2-Dioxazol-5-ones via Cobalt-Catalyzed C–H Bond Activation

Iku Tanimoto, Kentaro Kawai, Akane Sato, Tatsuhiko Yoshino,* and Shigeki Matsunaga*

*Faculty of Pharmaceutical Sciences, Hokkaido University, Kiat12, Nishi 6, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan

Abstract

A one-step synthesis of 4H-3,1-benzoxazin-4-ones from readily available Weinreb amides and 1,4,2-dioxazol-5-ones under Cp*Co(III) catalysis is described. The reactions proceeded in moderate to good yields with high functional group compatibility.

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Published online: 14th November, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13981
■ New Prenylated Bibenzyls from Bornean Liverwort Acrobolbus saccatus

Shean-Yeaw Ng, Takashi Kamada, Chin-Soon Phan, Monica Suleiman, and Charles S. Vairappan*

*Laboratory of Natural Products Chemistry, Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia

Abstract

Liverworts are the most primitive terrestrial plant which known to produce unique and wide variety of compounds. Ethyl acetate crude extract was subjected to several chromatographic techniques for purification. Three new compounds, saccatenes A-C (1-3) were isolated together with two known prenyl bibenzyl derivative, 2,2-dimethyl-5-hydroxy-6-carboxy-7-(2-phenylethyl) chromene (4) and radulanin A-5-one (5) from the Bornean liverwort Acrobolbus saccatus (Hook.) Trevis collected from Mountain Trus Madi, Sabah, Malaysia. The structures of the three new metabolites were established by analyses of the spectroscopic data (1D NMR, 2D NMR, HRESIMS and IR), and the antibacterial activity against eight selected human pathogenic species of bacteria were tested.

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Published online: 14th November, 2018

Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13984
■ Utilization of Chlobenthiazone and Benazolin-Ethyl as 4-Substituted 2(3H)-Benzothiazol-2-one Scaffolds

Masatoshi Kakuno, Shotaro Izawa, Taichi Takemoto, and Yoo Tanabe*

*Department of Chemistry, School of Scienece and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan

Abstract

N(3)-Substituted 4-aryl (or heteroaryl)-2(3H)-benzothiazol-2-ones were synthesized from readily accessible chlobenthiazone and benazolin-ethyl, a couple of N(3)-substituted 4-chloro-2(3H)-benzothiazol-2-one pesticides, utilizing Suzuki-Miyaura cross-coupling reactions (9 examples; 44–98% yield), although with less reactive stereocongested 4-chloro pendant substituent. In a similar fashion, N(3)-substituted 4-anilino (or BocNH)-2(3H)-benzothiazol-2-ones were synthesized from the 4-bromo analogues of the chlobenthiazone-utilizing Buchwald-Hartwig cross-coupling reactions (3 examples; 50–89% yield). In addition, a short synthesis of the key chloro-type quinone segment in natural mevashuntin with a unique 2(3H)-benzothiazol-2-one skeleton, was performed in three short steps with 61% overall yield. The obtained quinone segment functioned as a Diels-Alder reaction dienophile toward the Danishefsky-Kitahara diene as the model experiment. All schemes utilized a common cyclo-condensation using chlorocarbonylsulfenyl chloride for the construction of 4(ortho)-substituted 2(3H)-benzothiazol-2-one substrates.

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Published online: 12th November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)78
■ Consice Synthesis of TAN1251C

Yosuke Nagasaka, Tomohiro Asakawa, Sayaka Shintaku, Akitaka Masuda, Kosuke Matsumura, Makoto Inai, Yoshinobu Ishikawa, Masahiro Egi, Yoshitaka Hamashima, and Toshiyuki Kan*

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

Abstract

An efficient total synthesis of TAN1251C was accomplished by employing Ugi four-component condensation reaction and Dieckmann condensation to construct the spiro-fused cyclohexanone and γ-lactam ring structure. Diastereoselective reduction by side-chain-controlled hydrogenation of enamide 37 or Zn reduction of oxime 48 enabled construction of the amino group with the desired stereochemistry.

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Published online: 9th November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)51
■ Synthesis of Novel Resveratrol-phthalide Hybrid Compounds and Evaluation of Their Inhibitory Activities of Nitric Oxide Production

Tetsutaro Kimachi,* Tokutaro Ogata, Misae Doe, Mariko Sakanaka, Arisa Nishiuchi, Mio Aomatsu, Manami Tanaka, Maki Shimizu, Natsuko Yoshioka, Kurumi Kubota, Yui Teraoka, Chikako Nakajima, and Satoru Takahashi*

*School of Pharmaceutical Sciences, Mukogawa Women's University, 11-68 Koushien Kyuban-Cho, Nishinomiya, Hyogo 663-8179, Japan

Abstract

Four types of novel resveratrol-phthalide hybrid compounds were designed and synthesized systematically by Suzuki-Miyaura cross-coupling reaction. These hybrid compounds were evaluated upon an inhibitory effect of the LPS-stimulated NO production in murine macrophage cell line, RAW264.7. As a result, two of them showed stronger inhibitory activity than the original resveratrol.

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Published online: 9th November, 2018

Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13980
■ Effect of meta-Substituents on the Radical Scavenging Activity of 6-Chromanol Derivatives

Keiko Inami,* Yuta Okayama, Mariko Suzuki, and Masataka Mochizuki

*Division of Pharmaceutical Organic Chemistry, Faculty of Pharmaceutical Sciences, Sanyo-Onoda City University, 1-1-1 Daigakudori, Sanyo-Onoda-shi, Yamaguchi 756-0884, Japan

Abstract

A series of 8-substituted 6-chromanols, namely, the methyl- (4), methoxy- (5), amino- (6), methylamino- (7), dimethylamino- (8), 1-pyrrolidinyl- (9), piperidino- (10), 1-piperazinyl- (11), and morpholino- (12) derivatives, were synthesized and investigated to determine the effect of substitution meta to the phenolic OH group of a 6-chromanol on the radical scavenging activity. 7 and 9 possessed excellent radical scavenging properties. Our data showed that the lone-pair electrons on the nitrogen atom of the substituent at the m-position donated electron density into the conjugated p-orbitals on the 6-chromanoxyl radical by δ-donation through resonance, enhancing the radical scavenging activity.

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Published online: 7th November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)62
■ Mn(III)-based Oxidative Radical Ring-Expansion Reaction Using Squarate Derivatives: Selective Synthesis of Bis(butenolide)s and the Acetate Monomers

Jun-ichi Sasaki, Makoto Kobayashi, Yûsuke Ibe, and Hiroshi Nishino*

*Department of Chemistry, Graduate School of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan

Abstract

The Mn(III)-based oxidation of phenyl- and alkyl-substituted hydroxycyclobutenones selectively produced the bis(butenolide)s or the acetate monomers via the 5-endo radical cyclization depending upon the concentration of the reaction. A similar reaction of hydroxycyclobutenones bearing an alkenyl and alkynyl substituent did not produce any bis(butenolide)s or acetate monomers, but the 5-exo and 6-endo radical cyclization products including the unsaturated group. The oxidation of the hydroxycyclobutenones having an unsaturated substituent in the presence of alkenes afforded radical coupling products during the 5-exo radical cyclization. The reaction details, structure determination of the products, and the mechanism for the formation of the products are described.

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Published online: 6th November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)55
■ Atropisomeric and Conformational Properties of 6N-benzoyl- and 6N-p-tosyl-1,6-benzodiazocines: Comparison with Those of 1,5-Benzodiazepines

Hidetsugu Tabata,* Kazuya Murai, Kaoru Funaki, Chihiro Takemae, Tomohiko Tasaka, Tetsuta Oshitari, Hideyo Takahashi,* and Hideaki Natsugari*

*Faculty of Pharma Sciences, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan

Abstract

The atropisomeric and conformational properties of the eight-membered 1,6-benzodiazocines (2) with 6N-benzoyl (A) and 6N-p-tosyl (B) groups were examined by comparing them with those of the seven-membered 1,5-benzodiazepine congeners (1) (A, B). The conformation (orientation) of the benzene ring in the benzoyl and tosyl groups differed depending on the ring size (7/8) and N-substituent (-CO-/-SO2-). The activation free-energy barrier to rotation of the axes in N-p-tosyl derivatives (B) was shown to be much higher than those of the benzoyl derivatives (A).

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Published online: 5th November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)32
■ Model Studies for the Total Synthesis of 11-Demethoxymyrtoidine and Myrtoidine

Amaan M. Kazerouni, Danny E. Mancheno, and Simon B. Blakey*

*Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322, U.S.A.

Abstract

The malagasy alkaloids, isolated in the 1990s from Madagascan shrub Strychnos myrtoides, are a family of strychnos alkaloids whose members have been reported to potentiate chloroquine activity against resistant strains of Plasmodium falciparum malaria. 11-Demethoxymyrtoidine, myrtoidine, and malagashanine were identified as the major components of the shrub used by local populations to treat malaria. Herein we report our studies on model systems to construct the EF dihydropyran lactone moiety present in 11-demethoxymyrtoidine and myrtoidine, and initial studies toward the application of these strategies to the total synthesis of these alkaloids.

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Published online: 5th November, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13995
■ Synthesis of 4H-1,3,2-Benzodithiazin-4-imine 1,1-Dioxide Derivatives by Oxidative Cyclization of 2-(Aminosulfonyl)benzothioamide Derivatives with Iodine

Kazuhiro Kobayashi* and Daiki Fujiwara

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

Abstract

An efficient method for the construction of the 4H-1,3,2-benzodithiazine structure utilizing facile experimental operations from readily available starting materials is described. 2-Substituted (Z)-N-alkyl-4H-1,3,2-benzodithiazin-4-imine 1,1-dioxides can be obtained by the treatment of 2-(aminosulfonyl)benzothioamides, derived from the reaction between 2,N-dilithio derivatives of secondary benzenesulfonamides and isothiocyanates, with iodine in the presence of two equivalents of triethylamine.

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Published online: 31st October, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)40
■ Total Synthesis of (–)-Zephyranthine

Koki Ishii, Yuna Seki-Yoritate, Mizuki Ishibashi, Ming Wai Liaw, Takeshi Oishi, Takaaki Sato,* and Noritaka Chida*

*Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi, Kohoku-ku Yokohama 223-8522, Japan

Abstract

Stereoselective total synthesis of (–)-zephyranthine 1 based on the chiral pool approach starting from D-arabinose is described. The three consecutive chiral centers in (–)-zephyranthine were effectively constructed by the sequential [3,3] sigmatropic rearrangements (Claisen, Overman, and Claisen rearrangements) with chirality transfer of the hydroxy groups in D-arabinose.

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Published online: 26th October, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)47
■ Formation of an Aluminum Complex of 5-O-Caffeoylquinic Acid with Chiral Molecular Stacking under Vacuolar Condition

Kumi Yoshida,* Daisuke Ito, and Tadao Kondo

*Graduate School of Informatics, Nagoya University, Chikusa, Nagoya 464-8601, Japan

Abstract

5-O-Caffeoylquinic acid (neochlorogenic acid, 5CQ) is an essential co-pigment for blue coloration of hydrangea. 5CQ solubilizes a water insoluble aluminum complex of 3-O-glucosyldelphinidin (Dp3G) to give a water-soluble blue complex, in which both Dp3G and 5CQ chelate a single Al3+ ion. However, its isomer, 3-O-caffeoylquinic acid (chlorogenic acid, 3CQ), has no such effect and does not give blue complex. It was clarified that 5CQ was complexed with Al3+ with a chiral molecular stacking under physiological vacuolar condition as aq. solution at pH 4.0. However, 3CQ did not give such complex with Al3+. The difference in aluminum complexation between the isomers may result from the difference configuration of 5-OH and 3-OH group in quinic acid.

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Published online: 26th October, 2018

Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13957
■ Microwave Promoted Diels-Alder Reaction of 1,2-Dihydropyridine

Stephen R. Slauson,* Natalia Echeverry, Samantha Copeland, Alessandra Stoj, Melissa A. Kemp, and Maria Simon

*Department of Pharmaceutical Sciences, School of Pharmacy, University of Saint Joseph, 229 Trumbull Street, Hartford, CT 06103, U.S.A.

Abstract

The microwave-assisted Diels-Alder reaction between 1,2-dihydropyridine and activated dienophiles is reported. The conditions facilitate the production of the [2.2.2] scaffold in high yields with simple purification.

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Published online: 24th October, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)41
■ Heterospirocyclic 3-Amino-2H-azirines as Convenient Building Blocks in Peptide Synthesis

Christoph Strässler and Heinz Heimgartner*

*Department of Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

Abstract

Heterospirocyclic 3-amino-2H-azirines with a tetrahydropyran (Thp), tetrahydrothiopyran (Tht), or N-protected piperidine (Pip) moiety are useful reagents for the preparation of peptides containing the corresponding six-membered heterocyclic 4-amino-4-carboxylic acid unit. In the present study, tripeptides of the type H-Asp-D-Ala-Xaa-OMe, where Xaa is the heterocyclic amino acid, were prepared according to the ‘azirine/oxazolone method’.

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Published online: 24th October, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)33
■ Synthesis of Deuterated Cyclodopa with Hydrogen/Deuterium Exchange

Zetryana Puteri Tachrim, Shiori Nakagawa, Tadashi Nakamura, Fumina Ohashi, Natsumi Kurokawa, Haruna Wakasa, Yurika Tokoro, Yasuko Sakihama, Yasuyuki Hashidoko, Takeyuki Suzuki, and Makoto Hashimoto*

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

Abstract

CycloDOPA (5,6-dihydroxy-indoline-2-carboxylic acid, leukodopachrome) is one of metabolites derived from tyrosine, one of intermediate in melanin formation (mammalian) and betanidin main skeleton (betalain pigment in plant). Synthesis of deuterated cyclodopa via hydrogen/deuterium exchange by utilization of deuterium chloride (DCl) and deuterated triflic acid (TfOD) are reported. The novel fully deuterated aromatic cycloDOPA derivative can be formed depending on temperature and time of H/D exchange condition. The complete study of H/D exchange resulted in the selective deuterium between 4- and/or 7-position of aromatic hydrogen of cycloDOPA.

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Published online: 22nd October, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13974
■ HBr-Promoted Sulfenylation of Pyrazolones and 4-Hydroxycoumarins with N-(Organothio)succinimides

Hongai Jin, Wangyang Wang, Zhaohua Yan,* Rongxing Zhang, Mingchuang He, and Sen Lin*

*College of Chemistry, Nanchang University, No. 999, Xuefu Rd. 330031, China

Abstract

A convenient, effective and metal-free method for the synthesis of C-4 sulfenylated pyrazolones via HBr-promoted sulfenylation of pyrazolones with N-(organothio)succinimides as sulfur sources was developed. The method can be extended to apply for substrates 4-hydroxycoumarins. A series of C-4 sulfenylated pyrazolones and C-3 sulfenylated 4-hydroxycoumarins were smootly synthesized in good to excellent yields.

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Published online: 19th October, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)37
■ Selective Aromatic Nucleophilic Substitution of 4-(Dimethylamino)-2-methoxy-3-(trifluoroacetyl)quinoline with Thiols – DFT Calculation Study

Norio Ota, Yusuke Harada, Yasuhiro Kamitori, 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

The nucleophilic aromatic substitution proceeds exclusively at the 4-position of 4-(dimethylamino)-2-methoxy-3-(trifluoroacetyl)quinoline 1 by the reaction with various thiols to give the corresponding N-S exchanged products solely, and no O-S exchange reactions at the 2-position are performed. Our DFT calculation study provides a rational explanation regarding this complete selectivity based on energies of the adducts 6, 7 which are corresponding to the O-protonated Meisenheimer complexes at carbonyl oxygen in 3-trifluoroacetyl group. It was also investigated about influences of the solvents on the present unique selective substitution with thiols referring the results for the analogous selective substitution on 1 using amines as a nucleophile.

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Published online: 19th October, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)24
■ Four-Component Coupling Strategy for 2,3,4-Trisubstituted 3,4-Dihydroquinoline

Hiroki Yamagishi, Shun Tsuchiya, Hayate Saito, Keisuke Nogi, Jun Shimokawa, and Hideki Yorimitsu*

*Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan

Abstract

Trimethylsilyllithium attacked selectively at the 4-position of 2-(methylsulfanyl)quinoline. The lithium enamide intermediate generated in situ reacted with a series of electrophiles to introduce a substituent at the 3-position of the dihydroquinoline skeleton. Combined with the conversion of the 2-methylsulfanyl group to an aryl group via palladium-catalyzed Negishi-type coupling reaction, the net four-component coupling transformation in two steps provided a 2,3,4-trisubstituted 3,4-dihydroquinoline skeleton.

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Published online: 19th October, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)28
■ Arylboronic Acid-Mediated Glycosylation of 1,2-Dihydroxyglucoses

Sanae Izumi, Yusuke Kobayashi, and Yoshiji Takemoto*

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

Abstract

We explored direct dehydrative coupling of tetrahydro-2H-pyran-2,3-diol or a 1,2-dihydroxy sugar with various alcohols using a range of arylboronic acids. Among the catalysts, 2-borono-4-trifluoromethylbenzoic acid efficiently promoted acetalization of tetrahydro-2H-pyran-2,3-diol. Ferroceniumboronic acid showed the best catalytic activity for glycosylation of the 1,2-dihydroxy sugar. The major products were 1,2-cis-α-D-glucopyranosides.

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Published online: 19th October, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)34
■ Synthesis and DNA Cleavage Activity of Novel Spiro[cyclobutathiazole-4,4’-pyrazole] Derivatives

Eiichi Masumoto, Hayate Nagabuchi, Nobuhiro Kashige, Fumi Okabe-Nakahara, Fumio Miake, Kenji Yamagata, and Hiroshi Maruoka*

*Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan

Abstract

A facile and efficient synthesis of novel spiro pyrazole derivatives containing cyclobutathiazole moiety is described. The key substrate pyrazole-thiazolidine derivative as the building block for bis-heterocycles was formed via a Knoevenagel-type condensation of thiazolidinedione with pyrazol-3-one. Thermal treatment of the pyrazole-thiazolidine derivative with orthoesters in refluxing toluene caused an C-attack nucleophilic substitution, followed by an intramolecular cyclization/elimination sequence, giving the corresponding spiro[cyclobutathiazole-4,4’-pyrazole] derivatives. All the synthesized compounds were characterized by spectroscopic analysis and were tested for their DNA cleavage activity in vitro.

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Published online: 19th October, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13983
■ One-Pot Synthesis of 6H-Indolo[2,3-b]quinolines from 2-Nitrobenzaldehyde and Indole Derivatives via Domino Reaction

Wei-Nan Zhang, Jiao Xu,* Dao-Lin Wang,* and Zhen-Kai Zhong

*College of Chemistry and Chemical Engineering, Bohai University, 19, Keji Rd., New Songshan District, Jinzhou City, Liaoning Province 121001, China

Abstract

An efficient and simple method for the synthesis of 6H-indolo[2,3-b]- quinolones was described. The construction of this fused heterocycles system was achieved by alkylation–reduction–cyclization domino reaction of 2-nitro- benzaldehyde with indoles using SnCl2 as a promoter in [bmim]Br medium.

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Published online: 18th October, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)31
■ Studies toward the Synthesis of Perforatumone: Synthesis of the 7-Oxabicyclo[4.2.1]nonane-8,9-dione Core

Tatsuki Nakajima, Keita Takiguchi, Keisuke Yoshida, Akihiro Ogura, and Ken-ichi Takao*

*Department of Applied Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan

Abstract

Construction of the unique bridged bicyclic skeleton, 7-oxabicyclo[4.2.1]nonane-8,9-dione, of perforatumone was achieved. Key steps included a Dieckmann-type condensation, a Claisen rearrangement, and an intramolecular Michael reaction.

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Published online: 18th October, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-18-13986
■ Synthesis of 4-Arylisoquinoline-1(2H)-thione Derivatives by Sodium Hydride-Mediated Cyclizations of 2-(1-Arylethenyl)benzothioamides

Kazuhiro Kobayashi* and Takuma Ueyama

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

Abstract

A new and facile method for the general preparation of isoquinoline-1(2H)-thione derivatives has been developed. Thus, the sodium hydride-mediated cyclization of N-substituted 2-(1-arylethenyl)benzothioamides, which are derived from the reaction of 2-(1-arylethenyl)phenyllithiums with isothiocyanates, gives 2-substituted 4-aryl-3,4-dihydroisoquinoline-1(2H)-thiones. In addition, the use of N-substituted 2-(1-aryl-2-methoxyethenyl)benzothioamides from 2-(1-aryl-2-methoxyethenyl)phenyllithiums and isothiocyanates affording 2-substituted 4-arylisoquinoline-1(2H)-thiones is described.

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Published online: 17th October, 2018

Review | Special issue | Prepress
DOI: 10.3987/REV-18-SR(F)2
■ Chemistry of Nitroaziridines

Feiyue Hao and Nagatoshi Nishiwaki*

*School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada-cho, Kami, Kochi, 782-8502, Japan

Abstract

This review article introduced synthetic procedures for the preparation of structurally diverse nitroaziridines. In addition, this article also summarized reactivity of nitroaziridines caused by the inherent strain and high electrophilicity of the small ring. These properties facilitate their use as a functionalized building blocks in synthetic and medicinal chemistry.

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Published online: 17th October, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)44
■ Concise Synthesis of Anticancer Active trans-4-(4-Octylphenyl)prolinol

Junki Ando, Aoi Tazawa, Kohei Ishizawa, Minoru Tanaka,* and Hiroyoshi Takamura*

*Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

Concise synthesis of anticancer active trans-4-(4-octylphenyl)prolinol has been achieved. Regioselective iodination of aromatic compound and subsequent Suzuki–Miyaura cross-coupling with trans-1-octen-1-ylboronic acid produced the desired coupling product. Further transformation of this product afforded trans-4-(4-octylphenyl)prolinol. The synthesis of this anticancer compound has been performed with 23% overall yield and six steps, which have been improved in comparison with those (3.5% overall yield and eight steps) previously reported.

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Published online: 16th October, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)36
■ Concise Synthesis of Kalasinamide, Marcanine A, and Geovanine, and Antiproliferative Activity Evaluation of Their Azaanthracenones

Takashi Nishiyama, Noriyuki Hatae,* Kyohko Chikaraishi, Keisuke Uchida, Chika Yokoyama, Satoshi Hibino, and Tominari Choshi*

*Graduate School of Pharmacy & Pharmaceutical Sciences, Fukuyama University, Fukuyama, Hiroshima 729-0292, Japan

Abstract

The total syntheses of kalasinamide (1), marcanine A (2), and geovanine (3) have been conducted by the formation of a fused pyridone-ring azaanthracenone core based on a Curtius rearrangement that is followed by the microwave-assisted thermal electrocyclization of an isocyanato-containing 2-azahexatriene system. The antiproliferative activities of these synthetic compounds against the HCT-116 colon tumor cells were evaluated by the MTT assay.

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