HETEROCYCLES

■ Contents

■ Latest Development on the Methods of Synthesizing Ionic Liquids

Xiaoxia Xie, Lihua Li, Xian Wu, Cheng Ma, and Jinsheng Zhang*

*Department of Chemical Engineering and Environment Engineering, College of Chemistry, Liaoning Shihua University, Fu Shun, Liaoning Province, 113000, China

Abstract

Nowadays, in spite that the application of ionic liquids in some domains is still at infancy stage, the related synthetic technologies have got tremendous development over one century. In this paper, we made an overview on characteristics of five approaches to synthesize ionic liquids and compared the advantages and disadvantages of different methods, and gave recommendations for the best means of synthesizing to the objectives of related studies. Finally, the present work provides a full-scale literature review of the implementation of synthesizing ionic liquids, which could assist the corporations or individuals to search for the most suitable methods and lay the foundation for exploiting more ideal methods to obtain high purity and better yields of ionic liquids in the future.

■ Highly C3-Selective Direct Alkylation and Arylation of 2-Pyridones under Visible-Light-Promoted Photoredox Catalysis

Atifah Najib, Sho Tabuchi, Koji Hirano,* and Masahiro Miura*

*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

Abstract

An Ir photoredox catalyst-mediated highly site-selective direct alkylation and arylation of 2-pyridones has been developed. Under visible-light-promoted conditions, ethyl 2-bromo-2,2-difluoroacetate couples with various 2-pyridones exclusively at the C3 position. A similar photoredox catalysis is also effective for the direct C3-arylation with diaryliodonium triflates. Thus, these reactions occurs under very mild conditions (blue LEDs irradiation and ambient temperature) to form the corresponding C3-alkylated and arylated 2-pyridones of potential interest in medicinal and pharmaceutical chemistry.

■ A Colorimetric Chemosensor Based on Fluorescein for the Detection of Zn2+ in Aqueous Solution

Wei Wang, Ya-Nan Lei, Qing-Lei Liu, and Yan Gao*

*Department of Chemical Engineering, University of Science and Technology Liaoning, High-tech Zone of Anshan, Liaoning Province 114051, China

Abstract

A novel quinoline-functionalized fluorescein derivative HL was designed and used as a colorimetric chemosensor for the detection of Zn2+ over other commonly coexistent metal ions in aqueous solution at pH 7.2. Studies on its binding with different metal ions revealed a noticeable naked eye color change in the presence of Zn2+. The mechanism has been supported by Job’s plot evaluation, MS and 1H NMR spectroscopic studies. The association constant and the detection limits of sensor HL to Zn2+ were determined as 1.17×105 M-1 and 5.7 nM. This excellent selectivity and sensitive of HL to Zn2+ exhibited its potential application value in the biological monitoring and tracking of Zn2+.

■ Efficient One-Pot Synthesis of Benzo[e]pyrazolo[1,5-c][1,3]thiazine Derivatives under Copper-Catalyzed Conditions

Jiyang Jie, Haoyi Li, Meihui Piao, and Xiaobo Yang*

*College of Chemistry & Chemical Engineering, Shenyang Normal University, 253 Huanghe North Street Shenyang, China

Abstract

An efficient method has been developed for the synthesis of benzo[e]pyrazolo[1,5-c][1,3]thiazines via one-pot two-step reactions of readily available substituted 1-(2-halophenyl)-3-akylprop-2-yn-1-ones, hydrazine hydrochloride and β-oxodithioesters under mild conditions, and the corresponding benzo[e]pyrazolo[1,5-c][1,3]thiazines were obtained in good to excellent yields. The novel method affords a new strategy for the construction of diverse and useful poly N,S-heterocyclic compounds.

■ Prospective Study Directed to the Synthesis of Symmetrical Linked Bis-Rhodanine Derivatives with Their Antimicrobial Activity

Wael A. A. Arafa,* Raafat M. Shaker, and Saleh A. Rabeh

*Department Of Chemistry, Fayoum University, Fayoum 12975, Egypt

Abstract

One-pot three-component reactions of diamines, carbon disulfide and dialkyl acetylenedicarboxylates under conventional or ultrasound methods furnishing bis-rhodanines in good yields are described. Knoevenagel condensation reaction between 5,5’-methylene-bis-salicyaldehyde, pyrazole-3,5-dicarbaldehyde or terephthalaldehyde and N-alkylrhodanines afforded bis-arylidenerhodanines. While, the condensation between 2,6-diformylphenols and N-alkylrhodanines furnished only the mono-arylidenerhodanines. The newly synthesized compounds were characterized by HRMS and NMR spectral data. The compounds were screened for their in vitro antimicrobial activities. All the tested compounds showed pronounced activities, suggesting that the rhodanine moiety plays an important role in enhancing the antimicrobial properties of this class of compounds.

■ Synthesis of Quercetin Glycosides and Their α-Glucosidase Inhibitory Activities

Bixue Xu,* Guangyi Liang,* Zhonghang Wen, Zhanxin Hu, Jie Yuan, Hongju Chen, and Limei Zhang

*The Key Laboratory of Chemistry for Natural Products of Guizhou province and Chinese Academy of Sciences, Guiyang 550002, Guizhou, China

Abstract

A series of quercetin glycosides as the analogues of 3,5,5'-trimethyl-7-O-β-D-glucopyranosylquercetin (8) were synthesized, their structures were confirmed by 1H NMR, 13C NMR and MS. The inhibitory activities of those compounds against α-glucosidase were evaluated in vitro, in particular, the compounds V-c and V-d-2 showed promising bioactivities with IC50 of 19.4 μmol·L–1 and 19.7 μmol·L–1, are much higher than 8 (IC50 > 100 μmol·L–1). This research will provide a reference in the study of the synthetic methods and hypoglycemic activity for the quercetin glycosides.

■ Synthesis, Biological Evaluation of Some New Thiophene Derivatives

Sraa Abu-Melha*

*Department of Chemistry, Faculty of Science of Girls, King Khaled University, Abha 00966, Saudi Arabia

Abstract

The reaction of 2-pyridylacetophenone (2) with phenyl isothiocyanate gave thiocarbamoyl derivative 4 which on reaction with α-halocarbonyl compounds in a mixture of ethanol and N,N-dimethylformamide in the presence of triethylamine afforded thiophenes 6, 8, 10, 12 and 14 derivatives. While, when the same reaction was carried out in ethanol without N,N-dimethylformamide, it afforded the corresponding acyclic compounds 5, 7, 9, 11 and 13 which on reflux in N,N-dimethylformamide in the presence of triethylamine gave the corresponding thiophene derivatives. The newly synthesized compounds were characterized by analytical, spectral data and evaluated their antimicrobial activities. Compounds 6, 8, 10, 12, 13 and 14 were found to have high antimicrobial activities.

■ Stereoselective Synthesis of Chiral α,β-Unsaturated tert-Butyl Sulfoxides Derivatives by the Horner-Wadsworth-Emmons Reaction

Bo Liu, Lingyan Chen, and Zhihua Sun*

*College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, 333 Longteng Rd., Songjiang, Shanghai, 201620, China

Abstract

A series of chiral α,β-unsaturated tert-butyl sulfoxides derivatives was synthesized by the Horner-Wadsworth-Emmons reaction in good (E)/(Z) ratios. The enantioselectivity up to 89% and the yield up to 90% were achieved. These sulfoxides could be important intermediates in asymmetric synthesis.

■ Design and Synthesis of Benzothiazole Schiff Bases of Potential Antitumor Activitiy

Thuraya Al-Harthy, Raid Abdel-Jalil,* Wajdi Zoghaib, Maren Pflüger, Elisabeth Hofmann, and Harald Hundsberger

*Department of Chemistry, Sultan Qaboos University, P.O.Box 36 Al-Khoud 123, Oman

Abstract

In an attempt to develop a new class of selective antitumor agents, a novel series of benzothiazole derivatives was prepared via the condensation of 5-fluoro-6-(4-methylpiperazin-1-yl)benzo[d]thiazol-2-amine with aromatic aldehydes. The preliminary bioassay reveals that (4-fluorobenzylidene)-[5-fluoro-6-(4-methylpiperazin-1-yl)-benzothiazol-2-yl]-amine show specific anticancer cytotoxicity.

■ Synthesis and DNA Cleavage Activity of Functionalized Pyrazol-3-ones Containing Oxime Ester

Eiichi Masumoto, Nobuhiro Kashige, Fumi Okabe, 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 access to the synthesis of functionalized pyrazol-3-ones containing oxime ester from 4-hydroxypyrazol-3-ones, which were prepared starting from 4-alkylidenepyrazol-3-one, in moderate to good yields is reported. The structures of all products were identified by spectral data and some synthesized compounds were tested for their DNA cleavage activity.

■ Synthesis of the New Heterocyclic System 5,6,10b-Triazaacephenanthrylene, a Nitrogen Analogue of Aristolactams

Katarzyna Ostrowska,* Karol Dudek, and Bogdan Musielak

*Department of Organic Chemistry, Jagiellonian University, R.Ingardena 3, PL-30-060 Kraków, Poland

Abstract

We describe the two-step sequence for transforming enaminothioenone 1 to the planar semicyclic amidine 2 via an ylidenemalononitrile enamine intermediate, leading to the formation of the new π-conjugated heterocyclic system 5,6,10b-triazaacephenanthrylene, structurally related to the naturally occurring alkaloid aristolactams.

■ Approach to Phenanthroindolizidine Alkaloids Using Organic Azides with 1-Aryl Allylic Alcohols: Unexpected Tandem Reactions to Indenyl Aziridines via Nazarov Cyclization

Taiki Yokoi, Takahiro Sugiura, Hiroki Tanimoto,* Tsumoru Morimoto, Yasuhiro Nishiyama, and Kiyomi Kakiuchi

*Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan

Abstract

Organic azide cyclization reactions with 1-aryl allylic alcohols were investigated in a synthetic study of phenanthroindolizidine alkaloids. Unsaturated imines (enimines) were effectively obtained from the allylic alcohol adjacent to electron-rich aromatic rings under thermal reaction conditions. The tandem aziridination-Nazarov reactions to indenyl aziridines were preferred to the acid-mediated enimine formation via Schmidt reaction in the case of 3-aryl diallylic alcohols.