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69 data found. 1 - 30 listed Next Last

Published online: 12th June, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14094
■ Synthesis and Antimicrobial Evaluation of Some Novel Heterocycles as Antipyrine Derivatives

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

*Engineering Chemistry Department, Higher Institute for Engineering and Technology, New Damietta, New Damietta 34518, Egypt

Abstract

Novel antipyrine derivatives bearing pyran, pyridopyrimidine, chromene, benzothiazole, indole, pyrazole and pyridazine moieties were synthesized by using 2-cyano-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide (1) as a staring material. 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: 11th June, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14092
■ Divergent Synthesis of Indole-2-carboxylic Acid Derivatives via Ligand-free Copper-catalyzed Ullmann Coupling Reaction

Jiadi Zhou, Yongjian Chen, Junsong Huang, and Jianjun Li*

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

Abstract

This article describes a ligand-free copper-catalyzed Ullmann coupling reaction for the preparation of divergent indole-2-carboxylic acid derivatives including esters, amides and anhydrides. Various compounds 3, which could be synthesized from aldehydes conveniently, were used as substrate to provide the corresponding indole-2-carboxylic acid derivatives in moderate to good yields.

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Published online: 6th June, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14072
■ Modified Dehydroellagitannins from Davidia involucrata Leaves

Akari Esumi, Hiroe Aoyama, Yuuki Shimozu, Shoko Taniguchi, and Tsutomu Hatano*

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

Abstract

Davidia involucrata (Nyssaceae) is a naturally rare plant found in southern China. We isolated two previously undescribed ellagitannins, davicratinic acid B (5) and C (6), in addition to four known compounds, davicratinic acid A (1), helioscopinin B (2), granatin A (3), and pedunculagin (4). Spectral analyses revealed that compounds 5 and 6 are modified dehydroellagitannins with isomeric structures.

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Published online: 5th June, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14081
■ Secalonic Acids J–M, Four New Secondary Metabolites from the Marine-derived Fungus Penicillium oxalicum

Li Chen, Zhi-Hao Lu, Qin-Ying Liu,* Qiu-Hong Zheng, Lin Du, and Qi-Qing Zhang*

*Fujian Provincial Key Laboratory of Tumor Biotherapy, Fujian Cancer Hospital & Fujian Medical University Cancer Hospital, Fuzhou 350014, P. R. China

Abstract

Four new secalonic acid derivatives, secalonic acids J–M (1–4), were isolated from the marine-derived fungus Penicillum oxalicum. The planar structures of these compounds were elucidated by NMR and high-resolution mass spectrometric analyses. The absolute configurations were established by comparison of their experimental and calculated electronic circular dichroism spectra. Finally, these compounds were further evaluated for cytotoxic activities against the selected cancer cell lines in vitro. The results of flow cytometry demonstrated that compound 1 owned moderate activity of inducing apoptosis against HeLa cell.

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Published online: 3rd June, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-19-S(F)7
■ A Novel Condensed Heterocyclic Quinone with a Dibezofuranobisthiadiazole Skeleton

Kazuma Sugawara, Wataru Nojo, Yusuke Ishigaki, Junko Ohkanda, and Takanori Suzuki*

*Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan

Abstract

Upon oxidation of hydroquinone fused with 1,2,5-thiadiazole by using FeCl3, a novel dibenzofurano[1,2-c:6,7-c']bis[1,2,5]thiadiazole-type quinone was obtained whereas the similar dimerization-condensation process did not occur for the pyrazine-fused hydroquinone under the similar conditions.

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Published online: 3rd June, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-19-S(F)11
■ Isolation of Inohanalactone, a γ-Butyrolactone, from Nocardia inohanensis IFM0092T

Natsumi Kobayashi, Yasumasa Hara, Midori A. Arai, Shoko Hara, Tohru Gonoi, Takashi Yaguchi, and Masami Ishibashi*

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

Abstract

Because research on the genus Nocardia has not progressed as compared to the extensively studied genus Streptomyces, Nocardia is considered as a useful undeveloped resource for exploring natural products. In this study, a new γ-butyrolactone derivative, named inohanalactone (1), was isolated from Nocardia inohanensis IFM0092T. Inohanalactone possesses an aliphatic side chain containing 8 carbons, a vicinal diol, and a cis double bond. Inohanalactone was produced by N. inohanensis IFM0092T in the modified Czapek–Dox medium, whereas it was not produced in other media such as Nutrient broth, Waksman, and Yeast-Malt-Glucose media.

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Published online: 29th May, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14076
■ Total Synthesis of Thermoactinoamide A and Its Analogue

Yueguang Sun,* Hang-bin Li, Rong Zhou, Hailin Wang, Pengju Feng,* and Shihai Xu*

*Department of Chemistry, Jinan University, 601 Huangpu Avenue West, Tianhe District 10632, China

Abstract

Thermoactinoamide A, showing remarkable antibacterial properties, is a novel cyclic hexapeptide which was originally isolated from thermophilic bacterium. We disclosed here the first total synthesis of thermoactinoamide A and its analogue, anti-thermoactinoamide A, by the Fmoc solid-phase peptide synthesis and subsequent efficient macrolactamization. Thermoactinoamide A and its analogue can be obtained in 74% and 46% overall yield respectively without any isomerization under the developed methodology.

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Published online: 28th May, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14053
■ Synthesis and Optical Properties of Polyarylimidazole Derivatives Containing Naphthyl Groups In the 4,5-Positions for Coated and Non-Doped OLED Materials

Keiji Mizuki,* Daiki Sakai, Yuri Hatashima, and Taizo Hatta

*Department of Nanoscience, Faculty of Engineering, Sojo University, 4-22-1, Ikeda, Kumamoto-shi, 860-0082, Japan

Abstract

In this study, we describe the development of an imidazole emitting material, characterized by low concentration quenching via a bulky substituent group, for coated and non-doped OLEDs. Specifically, we synthesized novel 1,2,4,5-tetraarylimidazoles that have naphthyl groups replacing the bulky aryl groups at the 4,5-positions and investigated their optical, concentration quenching, thermal, and coating properties. We observe that the emitting materials had low concentration quenching properties and fluorescence occurred even in the film coating state.

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Published online: 28th May, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14077
■ Total Synthesis of Proposed Structure of Azepinobisindole Alkaloid Rhodozepinone

Tomoki Itoh and Takumi Abe*

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

Abstract

Total synthesis of the proposed structure of azepinobisindole alkaloid rhodozepinone has been accomplished from simple starting materials in 4 steps for the first time.

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Published online: 23rd May, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14070
■ Thymidine, 2-Thiothymidine, and 2-Selenothymidine: Comparison of Mismatch Discriminations

Takaki Habuchi, Takao Yamaguchi, and Satoshi Obika*

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

Abstract

Oligonucleotides modified using 2-thiothymidine (S2T) or 2-selenothymidine (Se2T), which are thymidine analogs bearing either sulfur or selenium atoms, respectively, have been independently shown to suppress the formation of mismatched wobble base pairs with guanine when forming a duplex with single stranded DNA. However, limited data comparing the base discriminations of S2T- and Se2T-modified oligonucleotides, especially toward single stranded RNA, are available. Here, we report a comprehensive data set of the base discriminations of S2T- and Se2T-modified oligonucleotides toward both single stranded DNA and RNA. Our results demonstrate that S2T- and Se2T-modified oligonucleotides have similar base discrimination abilities. An important feature observed in both the S2T- and Se2T-modified oligonucleotides is their extremely high base discrimination toward single stranded RNA. Thus, S2T and Se2T modifications may be useful for therapeutic oligonucleotides targeting single stranded RNAs.

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Published online: 23rd May, 2019

Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14086
■ Uncariagambiriines B and C, Alkaloid-Catechin Hybrids from Uncaria gambir Leaves

Mutsumi Oshima, Hiroe Aoyama, Yuuki Shimozu, Shoko Taniguchi, Takanori Miura, and Tsutomu Hatano*

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

Abstract

Gambiers, aqueous extracts from the leaves and twigs of Uncaria gambir, are used medicinally in Asian countries. Previously, we reported the isolation of uncariagambiriine (1) from U. gambir leaves, and its unique structure regarded as a catechin-alkaloid hybrid. Our continuing studies led to the isolation of two previously undescribed compounds named uncariagambiriines B (2) and C (3), in addition to the flavonoid glycosides, hyperoside and isoquercitrin. The structures of 2 and 3, isomeric to 1, were elucidated based on their spectral data.

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Published online: 22nd May, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14087
■ An Efficient Three-Component Synthesis of Novel Spiro[pyrazole-4,2’-quinazoline] Derivatives

Hayate Nagabuchi, Eiichi Masumoto, Fumi Okabe-Nakahara, and Hiroshi Maruoka*

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

Abstract

A simple, efficient, and three-component procedure has been developed for the synthesis of a series of spiropyrazol-3-one derivatives containing dihydroquinazoline moiety by the reaction of 1H-pyrazole-4,5-diones, 2-aminobenzophenones, and ammonium acetate in moderate to good yields. This method provides several advantages such as operational simplicity, shorter reaction time, and higher yields. All the synthesized compounds were characterized by spectroscopic analysis.

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Published online: 21st May, 2019

Review | Regular issue | Prepress
DOI: 10.3987/REV-19-905
■ Synthetic Methods of 1,3,2-Diazaphosphinine Systems

Tarik E. Ali,* Mohammed A. Assiri, Ahmed M. Fouda, Mohamed M. Hassan, and Noha M. Hassanin

*Department of Chemistry, Faculty of Education, Ain Shams University, Roxy, Cairo 11711, Egypt

Abstract

The present review considers all the literature data on methods developed for the synthesis of 1,3,2-diazaphosphinine systems starting from their appearance up to end 2018. The described main methods depended on the cyclization of 1,3-diamines, 1,2-aminoamide (β-aminoamide) and 1,2-aminonitrile (β-aminonitrile) compounds with phosphorus halides and sulfides.

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Published online: 21st May, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14085
■ A Mild and Efficient Ga(OTf)3-Catalysed Friedländer Reaction for the Synthesis of Quinolines

Hani Mutlak A. Hassan* and Iuliana Denetiu

*King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589 80216, Saudi Arabia

Abstract

The application of gallium triflate [Ga(OTf)3] for the synthesis of quinolines via the Friedländer reaction is described. This mild and straightforward method employed only 1 mol% of Ga(OTf)3 to deliver the quinoline products in excellent yields, demonstrating the high catalytic activity of this rare earth metal triflate.

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Published online: 13th May, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14075
■ Synthesis of Steroidal [1,2,4]Triazolo[1,5-a]pyrimidines and Their Antiproliferative Activities

Ning-Juan Fan, Jiang-Jiang Tang, Yuan-Feng Li, Yu-Bin Bai, and Xiao-Min Zhao*

*College of Veterinary Medicine, Northwest A＆F University, Yangling, Shaanxi 712100, China

Abstract

A facile strategy for the synthesis of steroidal [1,2,4]triazolo[1,5-a]pyrimidines 5a-g and 6a-g has been accomplished via a one-pot reaction of steroidal ketones, aromatic aldehydes and 3-amino-1,2,4-triazole in the presence of potassium tert-butoxide in refluxing tert-butanol. All the synthesized heterosteroids were evaluated for in vitro antiproliferative activity against human cancer cells by sulforhodamine B (SRB) assays. The preliminary results showed that compounds 6a and 6e possessed potent antiproliferative activities.

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Published online: 10th April, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-19-S(F)2
■ An Efficient Enantiospecific Synthesis of Neuroactive Glutamate Analogs

Shuntaro Tsukamoto, Hiyori Itagaki, Kenji Morokuma, Kei Miyako, Yuichi Ishikawa, Ryuichi Sakai, and Masato Oikawa*

*Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan

Abstract

Herein we report improved enantiospecific synthesis and some structure-activity relationships of our heterotricyclic artificial glutamate analogs bearing seven-membered ring for the C-ring. Starting from readily available oxanorbornene rac-3, optically pure (2R)-TKM-107, (2R)-IKM-154, and the antipodes were synthesized in total nine steps for each. Mice in vivo assay indicated that only the (2R)-enantiomer was active in both cases. Behaviors phenotypes observed in the mice assay suggested that these compounds are similar in mode of action to that of IKM-159 but with discrete potency.

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Published online: 10th April, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-19-S(F)3
■ Planar Chiral Phosphino[2.2]paracyclophanol-Catalyzed Highly Regio- and Stereoselective [3+2] Annulation Reaction of Morita–Baylis–Hillman Carbonates with Dicyanomethylideneoxindoles

Shinji Kitagaki,* Mayuka Tsuji, Hideki Teramoto, Naoko Takenaga, and Keisuke Yoshida

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

Abstract

To demonstrate the utility of [2.2]paracyclophane as a chiral organocatalyst backbone, we examined a planar chiral pseudo-ortho-diarylphosphino[2.2]paracyclophanol, phosphino-PCP-ol, which has a spacer aryl group between the pseudo-ortho-substituted PCP-ol backbone and the diarylphosphino group. We tested this catalyst in the [3+2] annulation reaction of Morita–Baylis–Hillman carbonates, derived from aromatic aldehydes and methyl acrylate, with 3-(dicyanomethylidene)-2-oxindole. The catalyst produced the desired 3-spirocyclopentene-2-oxindoles in high yields, and high regio-, diastereo-, and enantioselectivities.

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Published online: 12th March, 2019

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-19-14033
■ Synthesis of 1,2-Benzothiazole-3(2H)-thione 1,1-Dioxides by DBU-Promoted Cyclization of 2-(Aminosulfonyl)-N-methylbenzothioamide Derivatives

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 preparation of 2-alkyl-1,2-benzothiazole-3(2H)-thione 1,1-dioxides has been developed. Thus, the reaction of 2,N-dilithio derivatives of N-alkylbenzenesulfonamides with methyl isothiocyanate affords 2-[(alkylamino)sulfonyl]-N-methylbenzothioamides, which are treated with a catalytic amount of DBU in refluxing toluene to provide the desired products in moderate to good yields.

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Published online: 27th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)99
■ Diastereo–/Enantioselective Diels–Alder Synthesis of 14β-Hydroxysteroid Scaffolds: A Combined Experimental and DFT Study

Clovis Peter, Philippe Geoffroy, Takatsugu Murata, Takayuki Tonoi, Isamu Shiina,* and Michel Miesch*

*Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan

Abstract

Natural, non-natural and ent-14β-hydroxyandrostane derivatives closely related to the cardenolide and bufadienolide skeletons were readily available through highly diastereo-/enantioselective Diels–Alder reactions calling for high pressure or Lewis acid activation. Moreover, in the presence of (R)- or (S)-carvone as chiral dienophile, the Diels–Alder reaction took place under chemodivergent parallel kinetic resolution control. Based on experimental and DFT studies, reasonable mechanism insights were postulated to explain the concave/convex and endo/exo selectivities observed for the formation of the different Diels–Alder and Diels–Alder–Michael adducts.

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Published online: 25th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)83
■ Study toward an Asymmetric and Catalytic Synthesis of Koumine

David Reyes Loya, Jacques Maddaluno, and Michaël De Paolis*

*Normandie Université, UNIROUEN, INSA de Rouen, CNRS, Laboratoire COBRA (UMR 6014 & FR 3038), 76000 Rouen, France

Abstract

A synthetic study of koumine, a natural product with a densely functionalized and inspiring heterocyclic skeleton, was conducted by exploring a strategy of desymmetrization of 1,3-cyclohexanedione by an intramolecular vinylation reaction of an enolate under palladium catalysis to give a strained bridgehead 1,3-cyclohexanedione scaffold. In the course of the study, a domino ring expansion was discovered and developed.

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Published online: 25th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)82
■ The Effect of Lithium Ion on the Stereoselectivity of the Intramolecular Michael Addition of an N-Arylsulfoximine Anion

Aswin Garimalla, Quin Long, Christopher J. Cramer,* and Michael Harmata*

*Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA.

Abstract

The stereochemical outcome of the intramolecular Michael addition of a sulfoximine carbanion to a Z-configured α,β-unsaturated ester is dependent on lithium ion coordination between the oxygen on the sulfoximine and the carbonyl oxygen of the ester, based on both experimental and computational studies. Formally, this leads to a more sterically congested structure than might otherwise be preferred. Indeed, addition of HMPA, a substance capable of effective solvation of lithium cations, changes the stereochemical course of the reaction dramatically.

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Published online: 20th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)101
■ 1,2-cis-Selective Formation of a Unique Amino-Containing Amino Glycoside by Endocyclic Cleavage Strategy

Shino Manabe* and Yukishige Ito*

*Synthetic Cellular Chemistry Laboratory, RIKEN, Hirosawa, Wako, Saitama 351-0198, Japan

Abstract

2-Acetamido-4-amino-2,4,6-trideoxy-α-D-galactopyranoside (AAT), a unique aminated sugar unit, is often found in zwitterionic polysaccharides. Stereoselective formation of the 1,2-cis linkage of these unique sugar derivatives was achieved by an anomerization reaction based on an endocyclic cleavage process.

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Published online: 20th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)95
■ Construction of Pinpoint-Fluorinated Benzothiophene Frameworks Using Palladium-Catalyzed Cyclization of o-(Fluorovinyl)phenyl-Substituted Thiophenes

Kohei Fuchibe, Nobushige Tsuda, Kento Shigeno, and Junji Ichikawa*

*Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki 305-8571, Japan

Abstract

o-(2,2-Difluorovinyl)phenyl- or o-(1,2,2-trifluorovinyl)phenyl-substituted thiophenes underwent palladium(II)-catalyzed Friedel–Crafts-type cyclization on the fluorovinyl moieties to construct regioselectively monofluorinated or difluorinated benzothiophene frameworks (pinpoint-fluorinated naphtho[b]thiophenes). The cyclization of less nucleophilic 2-substituted thiophenes was effectively promoted by the addition of a CuOTf complex. Cyclization was also conducted in a tandem process, which facilitated the rapid synthesis of higher-order pinpoint-fluorinated PAHs (polycyclic aromatic hydrocarbons) bearing thiophene rings. Furthermore, cyclization was applied to the corresponding furan systems, which led to pinpoint-fluorinated naphtho[b]furans.

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Published online: 18th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)102
■ Synthesis of Di(3-thienyl)benzoporphyrin

Tetsuo Okujima,* Kota Muramatsu, Shigeki Mori, Masayoshi Takase, and Hidemitsu Uno

*Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan

Abstract

We have successfully synthesized 2,3-di(3-thienyl)benzo[b]porphyrin based on retro Diels–Alder reaction of bicyclo[2.2.2]octadiene(BCOD)-fused porphyrin and investigated its photoisomerization reaction.

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Published online: 15th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)94
■ Synthesis of a Poly-Heterocyclic Tetra-Substituted Alkene via a Palladium-Catalyzed Four-Fold Domino Reaction for the Design of Polymeric Molecular Switches

Taukeer A. Khan and Lutz F. Tietze*

*Institute of Organic and Biomolecular Chemistry, University of Goettingen, Tammannstrasse 2, 37077 Goettingen, Germany

Abstract

A facile synthesis of a complex poly-heterocyclic tetrasubstituted alkene 4 with intrinsic helical chirality containing two acrylate moieties suitable for polymerization is described. Compound 4 can act as a molecular switch and was prepared via a palladium-catalyzed four-fold domino reaction including two Sonogashira reactions and two domino-carbopalladation/C‒H-activation reactions.

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Published online: 15th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)97
■ Optimized Synthesis and Solid State Investigations on the Drug Candidate Encenicline Hydrochloride

Gerhard Laus, Sandro Neuner, Ramona Metz, Thomas Müller, Volker Kahlenberg, Thomas Gelbrich, Sven Nerdinger,* Erwin Schreiner, Verena Adamer, Klaus Wurst, and Herwig Schottenberger

*Global Portfolio, Sandoz GmbH, Biochemiestrasse 10, 6250 Kundl, Austria

Abstract

For the production of drug substances a robust, scalable process delivering the active pharmaceutical ingredient (API) in excellent chemical and polymorphic purity is required. For this purpose we developed a novel imidazole-mediated one-pot procedure for the preparation of encenicline hydrochloride monohydrate, which crystallizes directly from the reaction mixture as pure non-hygroscopic polymorph (Form I). Solid state studies revealed a series of additional new physical forms for which crystal structures have been determined by single crystal X-ray diffraction.

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Published online: 14th February, 2019

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)100
■ Preparation of Tricyclic Analog as CDE Ring Model of Renieramycin Marine Natural Product by Novel Photo-Induced Transformation of 6-Methoxy-1,2,3,4-tetrahydroisoquinoline-5,8-dione

Masashi Yokoya, Shohei Takahashi, and Naoki Saito*

*Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan

Abstract

2-Acetyl-6-[(benzyloxy)methyl]-9-methoxy-8-methyl-11,11a- dihydro-2H-pyrazino[1,2-b]isoquinoline-1,4,7,10(3H,6H)-tetraone (11a) was prepared as the CDE ring model of renieramycins, and its novel photo-induced transformation was demonstrated to construct a 1,3-dioxol ring.

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Published online: 14th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)103
■ Synthesis of Furan-Fused Silole and Phosphole by One-Pot Halogen Dance/Homocoupling of Bromofurfural Derivative

Kentaro Okano,* Yuki Murase, and Atsunori Mori

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

Abstract

Synthesis of a furan-fused silole and phosphole was achieved through a one-pot halogen dance/homocoupling of a bromofurfural derivative followed by the formation of the silole and phosphole skeleton.

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Published online: 13th February, 2019

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)87
■ Asymmetric Synthesis of t-Butyl 3-Alkyl-oxindole-3-carboxylates via Chiral Phosphoric Acid-Catalyzed Desymmetrization of Di-t-butyl 2-Alkyl-2-(2-aminophenyl)malonates

Kyoji Ishida, Masahiro Shimizu, Yu-suke Yamai, Itaru Natsutani, Shinichi Uesato, Yasuo Nagaoka, and Takaaki Sumiyoshi*

*Department of Life Science and Biotechnology, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Yamate-cho 3-3-35, Suita, Osaka, 564-8680, Japan

Abstract

We describe the asymmetric desymmetrization of di-t-butyl 2-alkyl-2-(2-aminophenyl)malonates to prepare enantioenriched t-butyl 3-alkyl-oxindole-3-carboxylates using (S)-TRIP, a chiral phosphoric acid. Optimization study increased the enantioselectivity up to 66% ee.

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Published online: 8th February, 2019

Communication | Special issue | Prepress
DOI: 10.3987/COM-18-S(F)77
■ Tripeptide-Catalyzed Asymmetric Aldol Reaction of Trifluoromethylated Aromatic Ketones with Acetone

Kazumasa Kon, Yoshihito Kohari,* and Miki Murata

*School of Earth, Energy and Environmental Engineering, Faculty of Engineering, Kitami Institute of Technology, 165 Koen-Cho, Kitami, Hokkaido 090-8507, Japan

Abstract

The development of H-Pro-Gly-Ala-OH (3d) to realize an inexpensive and simple organocatalytic system for the direct asymmetric aldol reaction of trifluoromethylated aromatic ketone 1 with acetone was achieved. The 3d-catalyzed aldol reaction of 1a–1j provided various aldol adducts 4a–4j with up to 81% yield and 77% ee. An investigation of the transition state via DFT calculations revealed that hydrogen bonding was important for the revelation of the enantioselectivity.

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69 data found. 1 - 30 listed Next Last