HETEROCYCLES

■ Contents

■ Oxidative Syntheses and Ring Opening of Oxazolines and Related Compounds by Ammonium Tribromide

Shinsei Sayama*

*Natural Sciences (Chemistry), Fukushima Medical University, Hikarigaoka, Fukushima, 960-1295, Japan

Abstract

Oxidative syntheses and ring opening of oxazolines and related compounds with trimethylphenylammonium tribromide (phenyltrimethylammonium tribromide, PTAB) or pyridinium hydrobromide perbromide (PHPB) were summarized. PTAB and PHPB were effective for respective syntheses of oxazolines, dihydrooxazines, and 6-bromobenzothiazoles. PTAB was also available for the conversion of oxiranes to dioxanes in the presence of 1,3-propanediol. The oxidative ring opening of furans, oxazolines, and dioxanes to respective furanones, cyanomethyl esters, and hydroxypropyl esters with PTAB or PHPB was also described.

■ 1,2-cis-α-Glucoside Formation from a 2-Benzyloxycarbonylamino-2-deoxy-α-D-glucopyranosyl Acetate Derivative by an Activating System That Used a Combination of Ytterbium(Ill) Triflate and a Catalytic Boron Trifluoride Diethyl Etherate Complex

Takashi Yamanoi,* Yoshiki Oda, Kento Fujita, and Akihiko Koizumi

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

Abstract

We investigated a glucoside formation reaction that utilized a 2-benzyloxycarbonylamino-2-deoxy-α-D-glucopyranosyl acetate donor derivative and various types of alcohol acceptors. The reaction was promoted by an activating system that used a combination of ytterbium(III) triflate and a catalytic boron trifluoride diethyl etherate complex, and it gave the corresponding 1,2-cis-α-glucopyranosides with high stereoselectivity. This glucoside reaction is a new and useful method for producing α-glucopyranoside derivatives from 2-amino-2-deoxy-D-glucopyranose.

■ A Convenient Synthesis of Novel Coumarin Derivatives with Anticipated Antimicrobial Activities

Asmaa Kamal Mourad,* Abd El-Naby Ibrahim Essawy, and Hussein Abdel-Azim Younus

*Department Of Chemistry, Fayoum University, Faculty of Science, Fayoum University zone 63514, Egypt

Abstract

Chalcone and coumarin are two substantial classes of natural products possessing significant antimicrobial activities. Hybrid compounds containing both structures have been synthesized in a good yield using Claisen-Schmidt aldolic condensation. The reaction of the new chalcones with active methylene compounds under different reaction conditions led to the construction of pyridine, pyran, pyrazole and pyridinone containing coumarin moiety with different functional groups. Investigating the antimicrobial activity of the new synthesized heterocycles, displays that 3-(2′-amino-3′-cyano-4′-(4-hydroxy-3-methoxyphenyly)pyrid-6′-yl)-coumarin 2a has the highest antimicrobial activity toward both Gram-positive and Gram-negative bacteria. Consequently, it was utilized as starting material for synthesis of more new fused heterocycles with anticipated high biological activity. All the new compounds are well characterized using, elemental analysis, FT-IR, 1H NMR, ESI-Mass Spectrum and tested for their antimicrobial activity.

■ AlCl3-Promoted Cyclization of β-Keto Derivatives with in situ Generated Enamines under Solvent-Free High Speed Ball Milling: An Efficient One-Pot Access to Polysubstituted 1,4-Dihydropyridines

Ji-Chao Zeng, Fei Yu, Abdullah M. Asiri, Hadi M. Marwani, and Ze Zhang*

*School of Biological & Chemical Engineering, Anhyui Polytechnic University, No. 8, Beijing Road, Wuhu 241000, China

Abstract

Under high speed ball milling (HSBM), a simple method for efficient synthesis of structurally diverse polysubstituted 1,4-dihydropyridines is developed via AlCl3-promoted Robinson-like cyclization of β-keto derivatives with in situ generated enamines. This one-pot protocol exhibits the advantages of high chemoselectivity, short reaction time, good functional group tolerance, mild reaction condition and easy work-up.

■ Synthesis of Isothiochromenes and 1,3-Dihydrobenzo[c]thiophenes by Iodine- and Hydrobromic Acid-Mediated Cyclizations of o-[(tert-Butylsulfanyl)methyl)]styrenes

Kazuhiro Kobayashi,* Takuma Ueyama, and Mai Horiuchi

*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

Methods for the syntheses of 4-substituted isothiochromenes and 1,1-disubstituted 1,3-dihydrobenzo[c]thiophenes have been developed. Thus, treatment of α-substituted o-[(tert-butylsulfanyl)methyl]styrenes, derived from α-substituted o-bromostyrenes using an easily operated four-step sequence, with iodine in the presence of sodium hydrogencarbonate gave isothiochromene derivatives. These tert-butyl sulfides were treated with concentrated hydrobromic acid to give 1,3-dihydrobenzo[c]thiophene derivatives.

■ Ultrasound-Mediated One-Pot Synthesis of the Fully Functionalized N,Nʹ-(1,3-Propane)bispyrroles

Huijun Liu,* Qi Ma, Zhen Lu, Qiang Zhao, Jinping Song, Kewei Wang, Feng Feng,* and Yong Guo*

*Institute of Applied Chemistry, Institute of Organic Chemistry, College of Chemistry and Environmental Engineering, Shanxi Datong University, NO 1602 xingyunstreet，datong city 037009, China

Abstract

Five fully functionalized N,Nʹ-(1,3-propane)-bispyrroles were synthesized by the tert-butyl isocyanide-mediated one-pot reaction of bisimines, aroyl chloride and dimethyl acetylenedicarboxylate under ultrasonic irradiation in good yield. The structures of N,Nʹ-(1,3-propane)-bispyrroles were characterized by 1H NMR and 13C NMR spectroscopy.

■ Synthesis of 8,9-Dihydropyrimido[4,5-e][1,4]oxazepin-7(5H)-ones by the Reaction of 1-(4-Chloropyrimidin-5-yl)alkan-1-ols with N-Alkylglycines

Kazuhiro Kobayashi,* Takashi Nogi, Yuka Tsunomori, Hidetaka Hiyoshi, and Kazuto Umezu

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

Abstract

A facile method for the construction of a new ring system, 8,9-dihydropyrimido[4,5-e][1,4]oxazepin-7(5H)-one, is described. The key feature of the synthetic route includes substitution of one of the two chloro groups of 1-(4,6-dichloropyrimidin-5-yl)alkan-1-ol derivatives, which can easily be derived from the reaction between 5-lithiated compound of 4,6-dichloro-2-(methylsulfanyl)pyrimidine (DCSMP) and aldehydes, with N-alkylglycines in the presence of triethylamine, followed by lactonization of the resulting hydroxy acids catalyzed by in situ generated triethylamine hydrochloride.

■ Three New C-Alkylated Flavones from the Flower of Rosa rugosa and Their Bioactivity

Jing Li, Huan-Huan Xing, Wei-Song Kong, Ye-Kun Yang, Lin Ye, Xin Liu, Yan-Ping Li, Gao-Xiong Rao, Hai-Ying Yang, Gang Du, Min Zhou, Qiu-Fen Hu, Guang-Yu Yang, Yun-Hua Qin,* and Xue-Mei Li*

*Key Laboratory of Tobacco Chemistry of Yunnan Province, China Tobacco Yunnan Industry Company, Hongjin Road 181#, Kunming, 650231, China

Abstract

Three new C-alkylated flavones (1-3), together with three known C-alkylated flavones (4-6), were isolated from the flower of Rosa rugosa. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D NMR techniques. Compounds 1-6 were evaluated for their anti-methicillin- resistant Staphylococcus aureus (anti-MRSA) activity. The results revealed that compound 1 showed good inhibition with inhibitaion zone diameter (IZD) of 13.4 ± 1.0 mm. Compounds 2-6 also showed weak inhibition with IZD in the range of 7.6 – 11.2 mm, respectively. Compounds 1-3 were also tested for the antioxidant activity, and they shows good antioxidant activity with an IC50 value of 4.2, 3.6 and 3.4 μg/mL, respectively.

■ Synthesis and Crystal Structure of 4-Trifluoroacetyl-3-phenylsydnone

Masami Kawase,* Ryosuke Saijo, Shigeki Mori, and Hidemitsu Uno

*Faculty of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan

Abstract

4-Trifluoroacetyl-3-phenylsydnone was first synthesized by trifluoromethylation of 4-formyl-3-phenylsydnone followed by oxidation of the corresponding trifluoromethyl alcohol. The structure of the product was determined by single-crystal X-ray analysis.

■ Synthesis of a Type of Bridged Heterocycles via Tetraynes

Xiangzhen Meng, Dong Cheng,* Shuang Lv, Jie Ma, and Yimin Hu*

*Laboratory of Functional Molecular Solids, Ministry of Education Anhui Key Laboratory of Functional Molecular-Based Materials, Institute of Organic Chemistry, School of Chemistry and Materials Science, Anhui Normal University Wuhu Anhui, China
*Institute of Chemical and Materials Engineering, Chaohu University, Chaohu Anhui, China

Abstract

A simple method has been developed for the synthesis of a type of bridged heterocycles using tetraynes. The strategy uses 1,3-diphenylisobenzofuran or 2,5-diphenylfuran and tetraynes as substrates and reactions proceed through an HDDA–[4+2] adduct. Products are obtained in moderate to good yield.

■ Flavones from Cassia leschenaultiana and Their Anti-Tobacco Mosaic Virus Activity

Guang-Hui Kong, Huan-Huan Xing, Yu-Ping Wu, Zhen-Yuan Xia, Jing Li, Ling Ye, Wei-Song Kong, Xin Liu, Yan-Ping Li, Gao-Xiong Rao, Qiu-Fen Hu, Guang-Yu Yang, Yin-Ke Li,* and Xue-Mei Li*

*Key Laboratory of Ethnic Medicine Resource Chemistry, State Ethnic Affairs Commission & Ministry of Education, School of Chemistry and Biotechnology, Yunnan University of Nationalities, Kunming, Jingming South Road, Chenggong New District, Kunming, Yunnan 650500, China

Abstract

Three new (1-3), together with three known flavones (4-6), were isolated from the whole plants of Cassia leschenaultiana. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D NMR techniques. Compounds 1-4 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activity. The results showed that compound 3 exhibited high anti-TMV activity with inhibition rate of 48.2%. This inhibition rate is higher than that of positive control (33.8%). Compounds 1, 2, and 4 also showed potential anti-TMV activities with inhibition rates of 29.5%, 26.2%, and 27.8%, respectively.

■ Synthesis of Dendrimer-Type Viologen and Its Use in Pd-Mediated Homocoupling of Aryl Halides

Manabu Kuroboshi,* Atsuki Kojima, and Hideo Tanaka

*Division of Chemsitry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

Dendrimer-type viologen (V2+.D.) was prepared from mesitylene and 4,4’-bipyridyl. Electroreduction of V2+.D. gave the corresponding quinoid (V0.D.), which promoted Pd-catalyzed homocoupling of aryl bromides Ar-Br to give the corresponding biaryls Ar-Ar in moderate to good yields.