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Published online: 31st July, 2014

Paper | Regular issue | Prepress
DOI: 10.3987/COM-14-13045
Efficient Installation and Elaboration of C4-C6 fused Furan Moiety in the Total Synthesis of Teucrium Clerodane Diterpenoids

Yen-Ku Wu, I-Chia Chen, Jia-Liang Zhu,* and Hsing-Jang Liu*

*Department of Chemistry, National Dong Hwa University, 1, Sec. 2, Hsueh Rd., Shou-Feng, Hualien 974, Taiwan, R.O.C.

Abstract

We previously reported the total synthesis of several Teucrium clerodane diterpenoids including teucvin (1), 12-epi-teucvin (2), montanin A (3) and teuscorolide (4) in a unified Diels-Alder approach. A full account for the tactical installation of the C4-C6 furan ring of 3 from an α,β-unsaturated lactone moiety, and the elaboration of the resulting furan unit into an α,β-unsaturated γ-hydroxyl lactone for preparing 4 is discussed herein. In addition, the transformation of 3 and its 12-epimer into 1 and 2 by the air-mediated furan oxidation reaction is described.

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Published online: 30th July, 2014

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-14-13051
Synthesis of Heterocycles via Palladium-catalyzed C-H Activation/Cyclization of Diazonium Salts (Part III): Phenanthridin-6-(5H)-ones

Pan Han, Jing Zhou, Cong-Cong Zhang, Ke Chen, and Zhen-Ting Du*

*College of Science, Northwest A&F University, Yangling 712100, Shaanxi Province, China

Abstract

A series of phenanthridin-6-(5H)-ones were synthesized through a palladium-catalyzed C-H activation/cyclization strategy using diazonium salts in good yields. The best conditions included Pd(OAc)2 as the catalyst, PPh3 as the ligand, toluene as the solvent, K2CO3 as the base and 60 oC as the optimal temperature.

Supporting Info. (3MB)PDF (288KB)

Published online: 25th July, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)54
Synthesis and Crystal Structure of (4S)-4-Benzyl-3-(4,5-dimethoxy-2-methylbenzoyl)-2,2-dimethyl-1,3-oxazolidine

Maria Chrzanowska,* Zofia Meissner, Joanna M. Chrzanowska, and Andrzej K. Gzella

*Faculty of Chemistry, Adam Mickiewicz University, ul. Grunwaldzka 6, 60-780 Poznań, Poland

Abstract

The synthesis of (4S)-4-benzyl-3-(4,5-dimethoxy-2-methylbenzoyl)-2,2-dimethyl-1,3-oxazolidine 6 was performed in 7 steps starting from veratraldehyde 7. A new oxidizing system TBHP-ebselen 12 was used for oxidation of 4,5-dimethoxy-2-methylbenzaldehyde 11 into carboxylic acid 13, being the crucial step of the synthesis. The latter was transformed first to chiral amide 14 using (S)-phenylalaninol and then cyclised to oxazolidine 6. The spatial structure and the absolute configuration of the latter one was confirmed by X-ray study.

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Published online: 24th July, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)66
Studies toward the Total Synthesis of Amphidinolide N: Stereocontrolled Synthesis of the C13–C29 Segment

Makoto Sasaki,* Yuki Kawashima, and Haruhiko Fuwa

*Laboratory of Biostructural Chemistry, Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai, 980-8577, Japan

Abstract

A stereocontrolled synthesis of the C13–C29 segment of amphidinolide N, a marine macrolide natural product that is extremely potent cytotoxic, is described.

Supporting Info. (5.9MB)PDF (578KB)

Published online: 24th July, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)46
Total Syntheses of Zwitterionic Indole Alkaloids, Flavocarpine and Dihydrovincarpine, by Extended Method for Substituted Pyridine Synthesis through Azaelectrocyclization

Yoshikatsu Hirose, Hiroshi Tsuchikawa, Toyoharu Kobayashi,* and Shigeo Katsumura*

*School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan

Abstract

The total syntheses of flavocarpine (1) and dihydrovincarpine (2) have been accomplished through the common intermediate, 2,4,5-trisubstituted pyridine compound 3 which was prepared by the accelerated 6π-azaelectrocyclization of 4-alkoxycarbonylazatriene 4 followed by aromatization of the resulting dihydropyridine derivative.

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Published online: 23rd July, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)41
Base Pair Recognition Ability of 2-(Methylamino)pyrimidin-4-yl Nucleobase in Parallel Triplex DNA

Yoshiyuki Hari,* Satoshi Kashima, Yuya Matsuda, Akihiro Sakata, Ryutaro Takamine, Shin Ijitsu, and Satoshi Obika*

*Graduate School of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 560-0871, Japan

Abstract

A phosphoramidite bearing a 2-(methylamino)pyrimidin-4-yl nucleobase was synthesized and the modified oligonucleotide (triplex-forming oligonucleotide, TFO) was successfully obtained using the phosphoramidite on an automated DNA synthesizer. UV-melting experiment of triplex DNA between the synthesized TFO and duplex DNA targets indicated that the 2-aminopyrimidin-4-yl unit in TFO could be a useful core structure for recognition of a TA base pair in duplex DNA.

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Published online: 23rd July, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)35
Design of Aza-polyquinanes via Fischer Indole Cyclization under Green Conditions

Sambasivarao Kotha* and Ajay Kumar Chinnam

*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India

Abstract

We have demonstrated a simple and an efficient synthetic route for the synthesis of aza-polyquinane derivatives involving Fischer indole cyclization as a key step under low melting mixture conditions.

Supporting Info. (2.8MB)PDF (318KB)

Published online: 22nd July, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)57
Mn(III)-Based Oxidative Cyclization of N-Aryl-3-oxobutanamides. Facile Synthesis and Transformation of Substituted Oxindoles

Nobutaka Kikue, Tetsuya Takahashi, and Hiroshi Nishino*

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

Abstract

The oxidation of 3-oxo-N-phenylbutanamides 1 with manganese(III) acetate in ethanol afforded dimeric 3,3'-biindoline-2,2'-dione derivatives 3–5. A similar reaction of N,2-disubstituted N-aryl-3-oxobutanamides 6 in acetic acid produced 3-acetylindolin-2-ones 7 bearing various substituents in good to excellent yields. The acetylindolinones 7 were easily deacetylated by treatment using neutral alumina in diethyl ether. Both the acetylindolinones 7 and deacetylated indolinones 8 were transformed by reduction into the substituted 1H-indoles.

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Published online: 17th July, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)40
Synthetic Study of Afritoxinone A: Stereoselective Construction of Furopyranone Moiety

Hideki Abe, Toshihiro Yoshie, Takumi Wagatsuma, Toyoharu Kobayashi, and Hisanaka Ito*

*School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan

Abstract

Stereoselective construction of the furopyranone moiety of the natural product afritoxinone A was demonstrated. This synthetic methodology features (i) stereoselective 1,4-addition of a tricyclic ring system, (ii) oxidative cleavage of the diol, followed by hydration of the resulting dialdehyde group, and (iii) acetalization via cationic cyclization of the pyranediol with the tert-butyl ester tether.

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Published online: 16th July, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)45
Palladium(0)-mediated C−S and O−H Bonds Cleavage Reaction in 2-Hydroxybenzyl Phenyl Sulfide: Formations of Oxyphosphorane and 1,2-Oxapalladacycle

Norio Nakata, Noriyuki Furukawa, Hiroki Kobayashi, Izuru Suzuki, and Akihiko Ishii*

*Department of Chemistry, Faculty of Science, Saitama University, Urawa, Saitama 338-8570, Japan

Abstract

Treatment of 2-hydroxybenzyl phenyl sulfide 3 with 1.5 equiv. of [Pd(PPh3)4] in toluene led to the unanticipated formation of oxyphosphorane 4 in 30% isolated yield. In contrast, the reaction of 3 with Pd(0) complex bearing PMe3 ligands in toluene afforded the corresponding 1,2-oxapalladacycle 7 and oxyphosphorane 9 in addition to dithiolato complex trans-[Pd(SPh)2(PMe3)2] 8.

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Published online: 16th July, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)48
Tandem [4+2] Cycloaddition/Aromatization Sequence of Allenyl 2-Bromo-3-vinylcyclohex-2-enyl Thioether to Naphtho[1,8-bc]thiophene

Noriyuki Hatae,* Aiichirou Kaji, Chiaki Okada, and Eiko Toyota

*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan

Abstract

A concise synthetic route of tetrahydro-3H-naphtho[1,8-bc]thiophene was developed. Allenyl 2-bromo-3-vinylcyclohex-2-enyl thioether underwent a tandem [4+2] cycloaddition/aromatization sequence to produce the naphthothiophene with high yield. A density functional study for the transition and reaction enthalpies was performed to elucidate the details of the reaction.

Supporting Info. (984KB)PDF (282KB)

Published online: 7th July, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)30
Synthesis and Structural Characterization of a Novel Organotellurium Compound: Dinaphtho[2,3-b;2’,3’-d]tellurophene

Mio Matsumura, Atsuya Muranaka, Naoki Kakusawa, Jyoji Kurita, Daisuke Hashizume, Masanobu Uchiyama,* and Shuji Yasuike*

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

Abstract

The first example of dinaphtho[2,3-b;2’,3’-d]tellurophene (1d) has been synthesized by the condensation of tellurium with 3,3’-dilithio-2,2’-binaphthalene. Single crystal X-ray analysis of 1d revealed that naphthalene and tellurophene rings are almost coplanar. A linear relationship (R2 = 0.971) between the atomic radius of Group 16 elements and the HOMO-LUMO gap energies of 1ad was found by density functional theory (DFT) calculations.

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Published online: 7th July, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)36
Synthesis of Photoreactive Diazirinyl Salicin Derivative to Elucidate Functional Analysis of the Bitter Taste Receptor

Munenori Sakurai, Takuma Yoshida, Lei Wang, Yuta Murai, Katsuyoshi Masuda, Yasuko Sakihama, Yasuyuki Hashidoko, Yasumaru Hatanaka, and Makoto Hashimoto*

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

Abstract

Salicin (salicyl alcohol glucoside) is a substance well known for its bitter taste. A photoreactive diazirinyl derivative of salicin will be utilized for the functional analysis of interactions between the bitter taste receptor and salicin. Glucosides of salicyl derivatives are more difficult than phenol derivatives that are unsubstituted at the ortho-position. A diazirinyl salicin derivative was synthesized at moderate yields by glucosidation of 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide and 2-hydroxy-4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzaldehyde in the presence of a phase-transfer catalyst, nBuEt3NBr, followed by reduction and deprotection.

PDF (471KB)

Published online: 30th June, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)38
2-Debromonagelamide U, 2-Debromomukanadin G, and 2-Debromonagelamide P from Marine Sponge Agelas sp.

Kenta Nakamura, Taishi Kusama, Naonobu Tanaka, Kanae Sakai, Tohru Gonoi, Jane Fromont, and Jun'ichi Kobayashi*

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

Abstract

Two new monomeric bromopyrrole alkaloids (1 and 2) and one new dimeric bromopyrrole alkaloid (3) were isolated from an Okinawan marine sponge Agelas sp. Spectroscopic analyses of these compounds revealed the structures of 13 to be 2-debromonagelamide U, 2-debromomukanadin G, and 2-debromonagelamide P, respectively. Antimicrobial activity of 13 was evaluated.

PDF (206KB)

Published online: 25th June, 2014

Review | Regular issue | Prepress
DOI: 10.3987/REV-14-798
Synthetic Routes towards Benzofuro[2,3-b]pyrroles and Benzofuro[2,3-b]indoles

Yuta Ito, Masafumi Ueda,* and Okiko Miyata*

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

Abstract

This review provides a summary of the synthetic methods currently available for the construction of benzofuro[2,3-b]pyrroles and benzofuro[2,3-b]indoles. The latter of these two scaffolds features as a key structural element in characteristic bioactive natural products.

PDF (855KB)

Published online: 24th June, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)24
Synthetic Studies on Saframycin Anibiotics: An Improved Synthesis of Tricyclic Lactam Intermediate and Construction of the Core Ring System of Saframycin A

Shinya Kimura, Shintaro Kawai, Masayuki Azuma, Yoshifumi Umehara, Yu-ichi Koizumi, Masashi Yokoya, and Naoki Saito*

*Department of Medicinal Chemistry, Pharmaceutical Chemistry, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan

Abstract

An improved synthesis of the tricyclic lactam intermediate of saframycin antibiotics and the construction of the core ring system having a cyano group at C-21 position were presented.1 The stereochemistry of several key intermediates was determined by X-ray crystallographic analysis.

PDF (471KB)

Published online: 19th June, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)25
Group-Assisted Purification (GAP) for Protection of Amino Acids using N-Phosphonyl Functional Groups

Guanghui An, Cole Seifert, Hao Sun, Yi Pan, and Guigen Li*

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

Abstract

Various phosphonyl halides have been synthesized and utilized as protection groups for amino acids. The protection synthesis was performed via GAP (Group-Assisted Purification) procedure under convenient conditions without the use of column chromatography and recrystallization. The synthesis can be carried out on applicational scales with excellent yields (82% - 98%). The phosphonyl protection of amino acids would provide a new greener tool for GAP peptide synthesis.

Supporting Info. (7.9MB)PDF (324KB)

Published online: 18th June, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)34
Generation and Reactions of Heteroaromatic Arynes using Hypervalent Iodine Compounds

Keisuke Gondo, Juzo Oyamada, and Tsugio Kitamura*

*Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo-machi, Saga, Japan

Abstract

The heterocyclic aryne precursors, (phenyl)[1-phenyl-6-(trimethylsilyl)benzotriazol-5-yl]iodonium triflate and [3-ethoxycarbonyl-6-(trimethylsilyl)indazol-5-yl](phenyl)iodonium triflate, were prepared from the cycloadducts of 4,5-bis(trimethylsilyl)benzyne generated from (phenyl)[2,4,5-tris(trimethylsilyl)phenyl]iodonium triflate. These precursors provide the corresponding arynes, 1-phenyl-5,6-didehydrobenzotriazole and 3-ethoxycarbonyl-5,6-didehydroindazole, to give the corresponding polycyclic heteroaromatic compounds in good to high yields.

Supporting Info. (1.2MB)PDF (297KB)

Published online: 13th June, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)32
Stereoselective Approach toward Ophiodilactones Based on an Intramolecular [2 + 2] Cycloaddition Reaction

Takaaki Matsubara, Jun Ishihara, and Susumi Hatakeyama*

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

Abstract

The highly enantio- and diastereoselective synthesis of a promising precursor of ophiodilactones A and B, tetrameric phenylpropanoids isolated from the ophiuroid Ophiocoma scolopendrina, is described. The synthesis involves an organocatalytic asymmetric Michael reaction, intramolecular [2 + 2] cycloaddition of a ketene to an alkene, Baeyer-Villiger oxidation, and construction of the C2 quaternary center as major transformations.

Supporting Info. (1.3MB)PDF (482KB)

Published online: 12th June, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)29
Synthesis and Evaluations of GLP-1 Secretion and Anti-Diabetic Effect in KKAy Mice of New Tricyclic Compounds

Daisuke Minehira, Daisuke Takeda, Shota Miyawaki, Atsushi Kato, Isao Adachi,* Akira Miyazaki, Ryuta Miyatake, Masahito Umezaki, Kyoko Miura, Yoshiro Kitahara, Kenji Sugimoto, Yuji Matsuya, and Naoki Toyooka*

*Graduate School of Science and Technology, Toyama University, Gofuku 3190, Toyama 930-8555, Japan

Abstract

Glucagon-like peptide-1 (GLP-1), which belongs to the family of incretins, plays important role for the regulation of plasma glucose. Accordingly, GLP-1-based therapies for type 2 diabetes have recognized as one of the most interesting target. In this study, we have found the new tricyclic compounds having strong GLP-1 secretion from human intestinal L cells, and anti-diabetic properties in spontaneously obese and diabetic KKAy mice. The most potent compound 5ka was obtained as the unexpected product, and we would like to report the details of the synthesis, structure elucidations, pharmacological activities on secretion of GLP-1, and anti-diabetic effects using diabetic KKAy mice.

Supporting Info. (8.8MB)PDF (960KB)

Published online: 11th June, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)33
Bis(diarylethenyl)thiophene, -bithiophene, and -terthiophene: A New Series of Violene-Cyanine Hybrid-Type Electron Donors

Yusuke Ishigaki, Hidetoshi Kawai, Ryo Katoono, Kenshu Fujiwara, and Takanori Suzuki*

*Division of Chemistry, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan

Abstract

The title fluorescent (oligo)thiophenes 1-3 were designed as new violene/cyanine-hybrid-type electron donors, which have two 4-methoxyphenyl groups each on the two cyanine parts. Voltammetric analyses showed that they all undergo reversible two-stage one-electron oxidation. The intramolecular short S(thiophene) -- Cipso(Ar) contacts were commonly present in their X-ray structures, and the coplanarily extended geometries are suitable for π-delocalization. Electrochemical oxidation of 1-3 caused continuous changes in their UV-Vis-NIR and fluorescence spectra although the oxidized species are too labile to be isolated.

PDF (571KB)

Published online: 10th June, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)26
Design and Synthesis of Conformationally Constrained Bicyclo[2.2.2]octane-based Unusual α-Amino Acid Derivatives via the Diels–Alder Reaction

Sambasivarao Kotha* and Milind Meshram

*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India

Abstract

We report a simple synthetic approach to various conformationally constrained bicyclic α-amino acid derivatives using the DielsAlder reaction as a key step. Moreover, we have investigated the reactivity pattern of various anthracene derivatives in relation to the DielsAlder chemistry.

Supporting Info. (2.1MB)PDF (433KB)

Published online: 9th June, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)28
Pd-Catalyzed Intramolecular Oxidative Coupling Reaction of 1,1’-Carbonyldiindoles

Takumi Abe and Minoru Ishikura*

*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan

Abstract

The palladium-catalyzed intramolecular oxidative coupling reaction of 1,1’-carbonyldiindoles was achieved by using Pd(OAc)2 and Cu(OAc)2, producing 1,1’-carbonyl-2,2’-biindolyls, which were then converted to tjipanazoles D and I.

PDF (230KB)

Published online: 4th June, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)31
Three-Way Output Molecular Response System based on Tetrakis(3,4-dialkoxyphenyl)-3,4-dihydro[5]helicenes: Perturbation of Properties by Long Alkyl Chains

Yusuke Ishigaki, Satoshige Yoshida, Hidetoshi Kawai, Ryo Katoono, Kenshu Fujiwara, Takanori Fukushima, and Takanori Suzuki*

*Division of Chemistry, Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan

Abstract

Starting from (S)-dimethyl 1,1'-binaphthyl-2,2'-dicarboxylate, optically pure (P)-3,3,4,4-tetrakis(3,4-dialkoxyphenyl)-3,4-dihydro[5]helicenes (P)-1 were prepared via bis(diarylhydroxymethyl)binaphthyl and/or tetraaryldinaphthodihydroxepin as key intermediates. Upon electrochemical oxidation to the corresponding (S)-1,1'-binaphthyl-2,2'-diylbis(diarylcarbenium)s (S)-22+, three kinds of spectral changes (UV-Vis, circular dichroism, fluorescence) were successfully observed. Compared to the methoxy compound, the octyloxy and hexadecyloxy derivatives exhibit a redshifted emission maxima in the dihydro[5]helicenes. The long alkyl chains induce step-by-step two-electron reduction of the binaphthyldiyl(dicarbenium)s whereas the dication with methoxy groups exhibits one-wave two-electron process.

PDF (464KB)

Published online: 3rd June, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)23
N-(2,3,4,5,6-Pentafluorophenyl)maleimide as a Powerful Dienophile in Dearomatizing Diels-Alder Reactions

Koichi Hagiwara, Masafumi Iwatsu, Daisuke Urabe, and Masayuki Inoue*

*Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Abstract

Here we demonstrate that N-(2,3,4,5,6-pentafluorophenyl)maleimide effectively promotes dearomatizing Diels-Alder reactions of 2,5-dimethylbenzene-1,4-diol and naphthalen-2-ol derivatives. The present reactions successfully converted the sp2-rich components to the desired products with multiple sp3-carbons in a single step. The adduct was further derivatized into the intermediate for our synthesis of 9-demethyl-10,15-dideoxyryanodol, an analogue of a sp3-rich natural product, in two steps.

PDF (360KB)

Published online: 28th May, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)18
Copper Mediated Formation of Carbon-Heteroatom Bonds Using Organoboron Reagents and Ultrasound

Bryan J. Musolino and George W. Kabalka*

*Chemistry Department, University of Tennessee, Knoxville, Tennessee, 37996-1600, U.S.A.

Abstract

This report summarizes research efforts focused on copper acetate mediated reactions to form new carbon-heteroatom bonds using organoboron reagents under ultrasound irradiation. The method involves the application of ultrasound irradiation to the Chan-Evans-Lam reaction to achieve O-arylation of phenols, N-arylation of anilines and indoles, and S-arylation of thiols. Ultrasound irradiation was found to decrease reaction times from 72 hours to 4 hours while improving the product yields an average of 20%.1 Representative C-O, C-N, and C-S coupling reactions were successfully scaled-up from the milligram to gram levels while maintaining good product yields offering potential applications in industrial processes.

PDF (403KB)

Published online: 27th May, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)10
Unusually Efficient Deformylative Synthesis of 1,2,8,9-Tetrasubstituted Dipyrrins from 4,5-Disubstituted Pyrrole-2-carbaldehydes

Mitsunori Oda,* Yurie Fujiwara, Yoshimitsu Kumai, Akira Ohta, and Ryuta Miyatake

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

Abstract

Upon heating in a mixture of hydrobromic acid and acetic acid, 4-arylmethyl-5-(4-methoxyphenyl)pyrrole-2-carbaldehydes (9ac) react to give 2,8-bis(arylmethyl)-1,9-bis(4-methoxyphenyl)dipyrrins (10ac) in high yields, demonstrating the first example of an unusually efficient deformylative transformation of pyrrole-2-carbaldehyde to dipyrrin. Dipyrrins 10 show a clear color change from red to blue, when exposed to Brønsted acid. Structure of 10a·H+ was determined by X-ray crystallographic analysis. The absorption change of 10a in the presence of a metal ion was also studied.

PDF (502KB)

Published online: 21st May, 2014

Communication | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)22
Three-Component Synthesis of Indolizines from Azaaromatic-Acethylenedicarboxylate Zwitterions with Acylzirconocene Chloride Complexes

Akio Saito,* Naoki Yamashita, Kohei Sudo, and Yuji Hanzawa

*Division of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588, Japan

Abstract

Acylzirconocene chloride complexes worked well as a reaction partner of azaaromatic-acetylenedicarboxylate zwitterions derived from isoquinolines or pyridines with diethyl acetylenedicarboxylate to afford the corresponding indolizine derivatives.

Supporting Info. (37KB)PDF (231KB)

Published online: 21st May, 2014

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)21
Diversity Oriented Approach to Oxepine Derivatives: Further Expansion via Diels‒Alder Reaction

Sambasivarao Kotha* and Rashid Ali

*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India

Abstract

Oxepine derivatives have been assembled via Diels‒Alder (DA) reaction as a key step and the latent dienes suitable for the DA reaction have been generated in situ from the sultine derivatives, which in turn were achieved by using commercially available rongalite. The “drug like” molecules assembled here may find useful applications in medicinal as well as bioorganic chemistry.

Supporting Info. (4.6MB)PDF (288KB)

Published online: 19th May, 2014

Paper | Special issue | Prepress
DOI: 10.3987/COM-14-S(K)9
Diversity Oriented Approach to Phenylalanine Derivatives via the Diels-Alder Reaction involving Sulfolene Intermediates

Sambasivarao Kotha* and Vijayalakshmi Bandi

*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India

Abstract

We report a new synthetic approach to highly functionalized phenylalanine derivatives via sulfolenes as latent diene equivalents. Here, the DielsAlder reaction has been used as a key step to assemble diverse unusual amino acid derivatives.

Supporting Info. (727KB)PDF (349KB)
48 data found. 1 - 30 listed Next Last