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Published online: 18th January, 2019

Review | Special issue | Prepress
DOI: 10.3987/REV-18-SR(F)5
Xanthates and Vinyl Esters, a Remarkably Powerful Alliance

Béatrice Quiclet-Sire and Samir Z. Zard*

*Department of Chemistry, Ecole Polytechnique, CNRS UMR 7652, 91128 Palaiseau, France

Abstract

The present brief overview highlights and discusses the synthetic potential of the degenerative radical addition of xanthates to vinyl esters. The process results in the formation of masked aldehydes bearing numerous functionalities. It allows expedient and convergent syntheses of various structures, including cyclic and open-chain enones, trifluoromethyl enones, dienes, pyrroles, dithietanones, thiophenes, hydroxytetralones, naphthalenes and naphthols.

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Published online: 18th January, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)35
Enviromentally-Benign Glycosylation Reaction Using Odorless Thio-glycosides and Hypervalent Iodine(III) Reagent

Koji Morimoto, Kana Yanase, Ibuki Odaka, Yasuyuki Kita,* and Tetsuya Kajimoto*

*Research Organization of Science and Technology, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan

Abstract

We discovered that the hypervalent iodine(III) reagent could mediate the glycosylation reaction by activating the thio-glycoside donors which were prepared from glycosyl 1-O-acetate and odorless p-octyloxybenzenethiol.  By using this method, trisaccharides as well as disaccharides could be easily synthesized under mild reaction conditions. All the chemicals employed in this method are enviromentally-benign.

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Published online: 15th January, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)75
α-Glucoside Formation from 2-Deoxy-2-(2,2,2-trichloroethoxycarboxamido)-α-D-glucopyranosyl Acetate Using an Activating System That Used a Combination of Ytterbium(III) Triflate and a Catalytic Boron Trifluoride Diethyl Etherate Complex

Takashi Yamanoi,* Yoshiki Oda, Akihiko Koizumi, Tsubasa Kawaguchi, Shin Yagihara, and Akihiro Yoshida

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

Abstract

This study describes the formation of α-glucoside from 3,4,6-tri-O-benzyl-2-deoxy-2-(2,2,2-trichloroethoxycarboxamido)-α-D-glucopyranosyl acetate using an activating system that used a combination of ytterbium(III) triflate and a catalytic boron trifluoride diethyl etherate complex. This glucoside formation using various types of alcohol acceptors proceeded with high α-stereoselectivity. The novel glucoside method employed in this study is a useful technique for producing 2-amino-2-deoxy-α-D-glucopyranoside derivatives because a 2,2,2-trichloroethoxycarbonyl group from an N-protecting group is easily removable.

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Published online: 8th January, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)89
Further Studies on the Gold-Catalyzed Oxidative Domino Cyclization/Cycloaddition to Give Polyfunctional Tetracycles

Tobias Groß, Korany A. Ali, Anne Jäger, and Peter Metz*

*Faculty of Chemistry and Food Chemistry, Organic Chemistry I, Technische Universität Dresden, Bergstraße 66, 01069 Dresden, Germany

Abstract

Enyne aldehydes and ketones with ester and ether functions in the tether between the reactive functional groups were subjected to a gold(III)-catalyzed domino process in the presence of a pyridine N-oxide as external oxygen donor. The resulting tetracyclic ketoethers were formed in high yields under mild conditions and with excellent induced diastereoselectivity for substrates featuring a stereogenic center within the enyne tether.

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Published online: 8th January, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)74
Second-Generation Synthesis of a Chiral Building Block for Oxygenated Terpenoids via a Ring-Contractive Coupling with a Secondary Alcohol

Sayuri Saito, Hiroyuki Yamakoshi, and Seiichi Nakamura*

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

Abstract

A much improved second-generation synthesis of a chiral building block, developed for the syntheses of C17-oxygenated steroids/triterpenoids and C9-oxygenated labdane diterpenoids, was accomplished by exploiting a ring-contractive coupling between an α-bromo-δ-valerolactone and (R)-seudenol, wherein the use of t-BuOK as a base allowed clean conversion to the corresponding tetrahydrofuran-2-carboxylate even with a small excess of the alcohol component.

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Published online: 7th January, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)88
Synthesis of Indolo[1,2-a]indole Derivatives by Cationic Au(I)-catalyzed Exo-selective Cycloisomerization and Their Photophysical Properties

Madhurima Hazra, Daisuke Inoue, Mamoru Ito, Kyalo Stephen Kanyiva, and Takanori Shibata*

*Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan

Abstract

Cationic Au(I)-catalyzed intramolecular cycloisomerization of N-(2-alkynylphenyl)indoles proceeded efficiently in exo-selective manner, and (Z)-10-(arylidene)indolo[1,2-a]indole derivatives were obtained in moderate to high yields. Their photophysical properties were also measured.

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Published online: 26th December, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)71
Separation of Minor Actinides from Lanthanides Using Immobilized Ligand Systems: The Role of the Counterion

Ashfaq Afsar, Petr Distler, Laurence M. Harwood,* Jan John, Jasraj S. Babra, Zoe Y. Selfe, Joeseph Cowell, and James Westwood

*Chemical Sciences Division, University of Reading, Whiteknights, Reading RG6 6AD, U.K.

Abstract

A CyMe4-BTPhen functionalized silica gel that selectively extracts Am(III) over Eu(III) from 4 M HNO3 with a separation factor > 154 has been developed. Evidence is presented that the counterion surrounding the M(III) in the proposed 1:1 [BTPhen:M(III)] complex plays an important role in the complexation of Am(III) and Eu(III).

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Published online: 26th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)49
Identification of Target Protein for Batzelladines as CD4

Jun Shimokawa* and Kazuo Nagasawa*

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

Abstract

Batzelladines are a family of polycyclic guanidine alkaloids. Among the congeners, batzelladines A-E were reported to inhibit the interaction of human immunodeficiency virus (HIV) gp120 protein with human CD4. Here, we designed a batzelladine photoaffinity probe bearing trifluoromethyl-3H-diazirine and biotin groups, and employed it to establish the identity of the target protein of batzelladines as CD4.

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Published online: 26th December, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)66
Syntheses and Acid-Stimulus Responsiveness of Aminobenzopyranoxanthene Spiroethers

Ryosuke Hosoda, Shinichiro Kamino,* Masashi Ueda, and Daisuke Sawada*

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

Abstract

Novel aminobenzopyranoxanthene spiroethers (ABPX-SEs) based on the spirocyclization of the hydroxymethyl group were synthesized from ABPX spirolactones (ABPX-SLs). The addition of an acid induces a ring-opening reaction to yield two colored monocationic and dicationic spiro-ring species of ABPX. The acid-stimulus responsiveness of the ABPX-SEs is lower than that of ABPX-SLs in polar organic solvents. In addition, the ABPX-SEs exhibit stepwise structural changes of the three equilibrium species at acidic pH, although rapid conversion from the spirolactone to dicationic species occurs in the case of ABPX-SLs.

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Published online: 26th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)57
Synthesis of LSD1 Inhibitor–Pyrrole Imidazole Polyamide Conjugates for Region-Specific Alterations of Histone Modification

Rui Qin, Shihori Takayanagi, Yusuke Kondo, Jiawei Li, Naoki Shiga, Masaya Nakajima, Ken-ichi Shinohara, Natsumi Yoda, Takayoshi Suzuki, Atsushi Kaneda, and Tetsuhiro Nemoto*

*Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba 260-8675, Japan

Abstract

Synthetic method of LSD1 inhibitor–pyrrole-imidazole polyamide conjugates for region specific alterations of histone modification is described. A (1S,2R)-tranylcypromine (PCPA) unit was coupled with an L-lysine part using a nosyl strategy. Conjugation of the inhibitor part with PIP tetramer units was achieved by amide bond formation using PyBOP as a condensation reagent.

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Published online: 19th December, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)61
Synthesis of a Tetracyclic Aminobenzimidazole Derivative via Tandem Cyclization of Triphenylguanidine

Yuki Akamatsu, Shinichiro Kamino, and Daisuke Sawada*

*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushima-Naka, Kitai-ku, Okayama, 700-8530, Japan

Abstract

We developed a new reaction for the one-pot synthesis of a fused cyclic compound from triphenylguanidine, which was thought to be tandem cyclization, with a moderate yield. In this reaction, conditions such as the metal reagent, oxidant, solvent, and ligand affected whether single or tandem cyclization was preferred.

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Published online: 19th December, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)79
An Intermolecular [4+3] Cycloaddition Reaction Using 3-Hydroxy-2-pyrone Derivatives with an Oxyallyl Cation

Takahiro Suzuki,* Takamune Yanagisawa, and Keiji Tanino*

*Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan

Abstract

An intermolecular [4+3] cycloaddition reaction using 3-hydroxy-2-pyrone derivatives with (2-silyloxy)allyl acetate was developed under Brønsted acid conditions to yield highly functionalized seven-membered carbocycles. The transformations of the cycloadducts are described.

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Published online: 19th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)70
Synthesis and Evaluation of Topoisomerase I Inhibitors Possessing the 5,13-Dihydro-6H-benzo[6,7]indolo[3,2-c]quinolin-6-one Scaffold

Tsutomu Fukuda,* Yuri Matsuo, Fuyuki Matsuoka, Naoki Yoshioka, Gen Onodera, Masanari Kimura, Fumito Ishibashi, and Masatomo Iwao

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

Abstract

Novel topoisomerase I inhibitors possessing the 5,13-dihydro- 6H-benzo[6,7]indolo[3,2-c]quinolin-6-one (BIQ) scaffold were designed and synthesized. This scaffold was constructed using sequential and regioselective functionalization of the pyrrole core through palladium-catalyzed cross-coupling, conventional electrophilic substitution, directed lithiation, and subsequent diphenylphosphoryl azide (DPPA)-mediated lactam ring construction. The obtained BIQs were evaluated for their topoisomerase I inhibitory activities and their antiproliferative activities in the panel of 39 human cancer cell lines established by the Japanese Foundation for Cancer Research (JFCR39).

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Published online: 18th December, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)69
Efficient Synthesis of Benzofuran Fused 1-Azaazulene

Hiroyuki Fujii,* Yusuke Hironaka, and Noritaka Abe

*Science Research Center, Yamaguchi University, Yamaguchi 753-8512, Japan

Abstract

The synthesis of benzofuran fused 1-azaazulene (cyclohepta[d]benzo[4,5]furano[2,3-b]pyrrole) (4) was achieved by one pot reaction of 2-chloro-1-azaazulene (1) with 2-iodophenol (2) under the conditions in the presence of Pd(OAc)2 and without using a ligand.

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Published online: 17th December, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)45
Palladium Acetate-catalyzed One-Pot Synthesis of Mono- and Disubstitued Pyridines

Shunya Mikami and Masahiro Toyota*

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

Abstract

A Pd-catalyzed one-pot synthesis of mono- and disubstituted pyridines was developed. The substituted pyridines were obtained from ketones or an aldehyde and 1,3-diaminopropane using a combination of catalytic Pd(OAc)2 and Cu(OAc)2. High-concentration reaction conditions enabled this catalytic reaction to be acid-free.

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Published online: 17th December, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)67
Preparation and Optical and Electrochemical Properties of Phthalocyanine with Four Bis(carbomethoxy)tetrathiafulvalene Units

Takeshi Kimura* and Tadafumi Chiba

*Center for Instrumental Analysis, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan

Abstract

α-Octaoctylphthalocyaninato Ni(II) with four bis(carbomethoxy)tetrathiafulvalene units was prepared from β-tetrakis(o-xylylenedithio)-α-octaoctyl- phthalocyaninato Ni(II) via C-S bond cleavage, carbonylation, and condensation with 4,5-bis(carbomethoxy)-1,3-dithiol-2-one. The structure of the product was determined by NMR and MALDI-TOF-MS and the electrochemical and optical properties were examined by cyclic voltammetry, UV-vis spectra, and ESR spectrum.

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Published online: 14th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)52
First Total Synthesis of Palmarumycin C6 based on Double Oxa-Michael Addition of 1,8-Dihydroxynaphthalene to 3-Bromo-1-indenone

Hirokazu Tsukamoto, Yumi Nomura, and Takayuki Doi*

*Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aza-aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan

Abstract

Synthetic studies on palmarumycin C6 with a naphthyl acetal at the C-3 position in 4,7-dihydroxy-1-indanone as a lower homologue of spirobisnaphthalenes are described herein. We investigated three approaches: 1) Nazarov cyclization of benzoylketene acetal, 2) intramolecular Friedel-Crafts acylation of naphtho[1,8-de]-1,3-dioxin-2-aryl-2-acetic acid chloride, and 3) double oxa-Michael addition of 1,8-dihydroxynaphthalene to 3-bromo-1-indenone. The last approach successfully afforded the natural product after the removal of acetates that serve as protecting groups for phenolic hydroxyls under acidic conditions.

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Published online: 14th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)60
Synthesis, Conformation, and Biological Activities of a Des-A-Ring Analog of 18-Deoxy-aplog-1, a Simplified Analog of Debromoaplysiatoxin

Yoshiki Ashida, Ryo C. Yanagita,* Yasuhiro Kawanami, Mutsumi Okamura, Shingo Dan, and Kazuhiro Irie

*Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kagawa 761-0795, Japan

Abstract

10-Me-Aplog-1 as a simplified analog of tumor-promoting debromoaplysiatoxin and a potent activator of protein kinase C (PKC) is a promising chemotherapeutic agent. In this study, we synthesized a des-A-ring analog (4) of 18-deoxy-aplog-1 as a synthetically-accessible analog. Compound 4 retained the conformation of the PKC-recognition part of aplogs. Moderate affinity for conventional PKC isozymes (α, β, γ) and anti-proliferative activity against NCI-H460 (lung) and MKN45 (stomach) human cancer cell lines were observed. The results suggest that 4 could serve as a lead compound for the development of conventional PKC isozyme-selective chemotherapeutic agents.

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Published online: 13th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)46
Synthesis and Hybridization Properties of Oligonucleotides Including 2ʹ-N-alkoxycarbonyl-2ʹ-amino-LNA Derivatives

Takashi Osawa, Shoko Yamashita, Ayumi Nakanishi, Yuta Ito, and Yoshiyuki Hari*

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

Abstract

2ʹ-Amino-LNA is an attractive material that helps in realizing the practical use of oligonucleotides because it can stabilize complexes with complementary strands and various substituents can be introduced on the 2ʹ-amino group. Here, 2ʹ-N-alkoxycarbonyl derivatives of 2ʹ-amino-LNA were newly designed, synthesized, and incorporated into oligonucleotides. The results of UV-melting analysis indicated that 2ʹ-N-alkoxycarbonyl-modified 2ʹ-amino-LNA could enhance the stability of the duplex formed with single-stranded RNA and the triplex formed with double-stranded DNA.

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Published online: 12th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)58
Mechanistic Insight into Catalytic Aerobic Chemoselective α-Oxidation of Acylpyrazoles

Seiya Taninokuchi, Ryo Yazaki,* and Takashi Ohshima*

*Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan

Abstract

Mechanistic studies on catalytic aerobic chemoselective α-oxidation of acylpyrazoles, including control experiments, kinetic isotope effect experiments, and radical clock experiments, are described. The key to promoting the reaction was the in-situ generation of a copper(II) peroxo complex, which serves as a Lewis acid/Brønsted base cooperative catalyst for efficient enolization. The present catalysis was applicable to late-stage α-oxidation of functionalized acylpyrazoles. A preliminary diastereoselective reaction using readily available chiral acylpyrazoles demonstrated that the present catalysis provided access to optically active α-hydroxy acid derivatives.

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Published online: 12th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)14
Exploration of Moderate Conditions and Substrate Variation in the Direct Condensation between Phthalide and Primary Amine Catalyzed by GaCl3. Are Aliphatic Amines Less Reactive than Aromatic Ones?

Ichiro Takahashi,* Yoshinori Nishiwaki, Kenta Saitoh, Takatoshi Matsunaga, Akihiro Aratake, Toshio Morita, and Shinzo Hosoi

*Department of Applied Chemistry and Biotechnology, Faculty of Engineering, University of Fukui, 9-1 Bunkyo 3-chome, Fukui-shi, 910-8507, Japan

Abstract

Direct condensation between phthalide and a primary amine in the presence of Lewis acid was achieved for the first time in organic solvent-diluted reaction systems catalyzed by GaCl3. The peripheral aspects of this reaction is discussed.

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Published online: 12th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)73
Asymmetric Synthesis of 2,3-Dimethoxy-8-oxoberbine, Precursor of O-Methylbharatamine

Maria Chrzanowska,* Agnieszka Dreas, and Zofia Meissner

*Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland

Abstract

The enantiospecific and enantioselective syntheses of 2,3-dimethoxy-8-oxoberbine were performed using the lateral metallation methodology. In the enantiospecific synthesis (4S)-2,2,4-trimethyl-3-(o-toluoyl)oxazolidine incorporating (S)-alaninol as the chiral auxiliary was applied. The addition reaction of benzylic anion generated in situ from chiral oxazolidine into 6,7-dimethoxy-3,4-dihydroisoquinoline led to the protoberberine with high enantiomeric excess. Enantioselective synthesis of 2,3-dimethoxy-8-oxoberbine was performed with achiral 2,2-dimethyl-3-(o-toluoyl)oxazolidine in the presence of chiral ligands. Among them (–)-sparteine and (+)-sparteine surrogate turned out to be the most efficient ones.

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Published online: 10th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)68
β-Trichloroacetylation of Cyclic Amines: Application to Synthesis of Chiral Azabicyclo-N-oxyls

Masami Kuriyama, Satoshi Kamogawa, Kosuke Yamamoto, and Osamu Onomura*

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

Abstract

β-Trichloroacetylation of cyclic amines was developed under mild reaction conditions, and the desired trichloroacetylated products were obtained in good yields. This method was applied to the preparation of optically active azabicyclo compounds, which were converted to chiral azabicyclo-N-oxyls.

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Published online: 5th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)56
Synthetic Studies on Pyrroloindolizidine Skeleton Based on Gold–Catalyzed Hydroamination–Enamine Cyclization–Ring–Closing Metathesis Strategy

Kenji Sugimoto,* Natsumi Matsuo, Daisuke Tominaga, and Yuji Matsuya*

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

Abstract

A pyrroloindolizidine skeleton, which is observed in myrmicarin alkaloids isolated from African ant, is highly unique, oligocyclic indolizidine derivative. We describe here an attempt on a synthesis of a pyrroloindolizidine skeleton with our originally developed gold–catalyzed cascade reaction and a newly developed synthetic route for the skeleton via gold–catalyzed hydroamination–enamine cyclization–ring–closing metathesis.

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Published online: 5th December, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)59
Rapid Stereoselective Syntheses of Heteroarene-Fused Azacycles via Diastereoselective Conjugate Addition of Heteroaryl Substituted Lithium Amides

Stephen G. Davies,* Ai M. Fletcher, Katherine E. Holder, Paul M. Roberts, James E. Thomson, and David Zimmer

*Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K.

Abstract

Conjugate addition of heteroaryl substituted lithium amides to a range of α,β-unsaturated esters followed by in situ enolate oxidation with (–)-(camphorsulfonyl)oxaziridine gave the corresponding α-hydroxy-β-amino esters. Subsequent Friedel-Crafts type cyclisation of these α-hydroxy-β-amino esters gave a range of heteroarene-fused azacycles in good yields and high diastereoselectivities.

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Published online: 3rd December, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)76
Divergent Synthesis of Photoaffinity Probe Candidates by Click Reactions of Azido-Substituted Aryltrifluoromethyldiazirines

Kenji Watanabe, Junpei Tsuda, Hidenori Ochiai, Takashi Niwa, and Takamitsu Hosoya*

*Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan

Abstract

Two types of azido-substituted aryltrifluoromethyldiazirine units have been designed and prepared for the divergent synthesis of photoaffinity probe (PAP) candidates. Using these azides, various aryltrifluoromethyldiazirine derivatives have been rendered easily synthesizable by several click reactions, as well as the Staudinger reduction affording the corresponding aniline. The triazole-conjugated aryltrifluoromethyldiazirine derivatives prepared in this study showed normal photoreactivity compared with those reported previously. These results indicate the utility of these azido-substituted aryltrifluoromethyldiazirine units for development of PAPs for target identification of bioactive compounds.

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Published online: 30th November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)72
Synthesis of Diverse 3-Azido-5-(azidomethyl)benzene Derivatives via Formal C–H Azidation and Functional Group-Selective Transformations

Yoshitake Nishiyama, Yoshihiro Misawa, Yuki Hazama, Kazuhiro Oya, Suguru Yoshida,* and Takamitsu Hosoya*

*Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan

Abstract

3-Azido-5-(azidomethyl)benzene derivatives are useful compounds for preparing diverse bistriazole compounds and photoaffinity probes for target identification of bioactive compounds. To more easily synthesize a diverse range of diazido compounds, a facile method for synthesizing diazido compounds bearing a transformable functional group, such as iodo, bromo, methoxycarbonyl, or cyano group, was developed. This method is based on formal C–H azidation of 1,3-disubstituted benzenes via regioselective borylation followed by deborylative azidation, with subsequent transformations, such as that of a one-carbon unit on the benzene ring to an azidomethyl group. The functional groups of the diazido compounds were efficiently transformed to various connecting groups, including carboxy, (succinimidyloxy)carbonyl, hydroxymethyl, formyl, bromomethyl, tosylthiomethyl, ethynyl, diazoacetyl, bromoacetyl, boryl, hydroxy, aminocarbonyl, amino, and isothiocyanato groups, leaving the azido groups untouched. Several diazido building blocks were used to prepare diazido compounds by forming amide, thiourea, and sulfide bonds via conjugation at the connecting groups. These results show that the method described here would facilitate diazido probe syntheses and bistriazole library construction.

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Published online: 28th November, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)50
Acetal Elimination Reaction Accompanied with Regioselective Ring Opening of 1,4-Bisacetal-1,4-epoxy-1,4-dihydronaphthalenes

Yoshinari Sawama,* Takahiro Kawajiri, Yuta Yamamoto, Yuko Shishido, Ryota Goto, and Hironao Sajiki*

*Laboratory of Organic Chemistry, Gifu Pharmaceutical University 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan

Abstract

1,4-Epoxy-1,4-dihydronaphthalenes are useful precursors to synthesize 1-naphthols by an acid-catalyzed ring opening of their 1,4-epoxy moieties. 1-Acetal-substituted 1,4-epoxy-1,4-dihydronaphthalene was also converted to 1-naphthol via the unique iron-catalyzed ring opening of the 1,4-epoxy moiety followed by the elimination of the acetal moiety. The present method could be applied to the regioselective syntheses of highly-functionalized 4-formyl-1-naphthols from the unsymmetrical 1,4-bisacetal-substituted 1,4-epoxy-1,4-dihydronaphthalenes.

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Published online: 28th November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)85
Synthesis and Properties of a Tricyclic Hexaketone Monohydrate with Hexabutyl Side Chain

Mio Ishita, Masanori Ohkoshi, Yoshiyuki Kuwatani, Hiroyuki Otani, Tohru Nishinaga, and Masahiko Iyoda*

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

Abstract

A tricyclic hexaketone monohydrate with a hemiacetal structure was synthesized by the ruthenium-catalyzed oxidation of butyl-substituted tribenzotetradehydro[12]annulene-1,2-dione. The oxidation of the annulenedione afforded unique [12]annulene-1,2,5,6,9,10-hexaone, followed by the cyclization to produce corresponding tricyclic hydrate containing two dihydrobenzopyranone rings. The tricyclic hexaketone hydrate weakly interacts with methanol and ethylene glycol to form 1:1 complexes in solution.

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Published online: 22nd November, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)65
The Practical Synthesis of Dissymmetrical 1,3,5-Trioxazatriquinane Derivatives Comprised of Three Distinct Carbonyl Compounds

Shigeto Hirayama, Koji Obayashi, Naohisa Wada, Kousuke Ohyama, Shizuho Fuku, Koji Koyano, Fumika Karaki, Kennosuke Itoh, Hiroshi Nagase, and Hideaki Fujii*

*Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan

Abstract

We have previously synthesized various 1,3,5-trioxazatriquinane derivatives consisting of not only three identical carbonyl compounds but also two identical carbonyl moieties as well as another type of carbonyl compound. However, dissymmetrical derivatives prepared from three distinct carbonyl compounds have not yet been selectively synthesized. Herein, we developed a selective synthetic method of such dissymmetrical derivatives: free α-hydroxyaldehydes were slowly added to a solution of protected α-hydroxyaldehydes, ammonium chloride, and sodium acetate to selectively provide key intermediate oxazolines, which were successfully converted into the objective dissymmetrical derivatives.

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