HETEROCYCLES

■ Contents

■ Development of Fluorescent 2-Pyrone Derivatives Using Ketene Dithioacetals for Organic EL Devices

Masayori Hagimori, Naoko Mizuyama, Yasuhiro Shigemitsu, Bo-Cheng Wang, and Yoshinori Tominaga*

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

Abstract

In recent years, organic electro luminescent (EL) materials have received considerable attention due to their potential application in next-generation display devices with high brightness levels, wide color ranges, and wide viewing angles. Fluorescent 2-pyrone derivatives have been synthesized using a convenient method involving ketene dithioacetals, which emit fluorescence (red, green, and blue) in both solution (dichloromethane and ethanol) and solid state. The structure-activity relationships of various 2-pyrone derivatives have been clarified.

■ Application of Stable Nitrenium Ions to Preparative Organic Chemistry

Yasuo Kikugawa*

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

Abstract

Nitrenium ions and their related species are involved in many important chemical and biological processes. The present review will survey the recent progress of their utility in preparative organic chemistry.

■ Synthesis of Open-Chain C21-C40 Fragment of Azaspiracid-1

Masato Oikawa,* Taizo Iwayama, and Makoto Sasaki*

*Laboratory of Biostructural Chemistry, Graduate School of Life Sciences, Tohoku University, 1-1 Tsutsumidori-amamiya, Aoba-ku, Sendai 981-8555, Japan

Abstract

Here, we report a synthesis of a differentially protected, open-chain C21–C40 fragment of azaspiracid-1, corresponding to the lower half EFGHI-ring domain. The synthesis features modular coupling of three advanced intermediates, aiming for diverted analogue synthesis. A new method for construction of E-ring moiety amenable to the diverted synthesis is also reported.

■ A Chiral “Roofed” cis-Diamine-Ru(II) Complex: An Efficient Catalyst for Asymmetric Transfer Hydrogenation of Ketimines

Hirofumi Matsunaga, Kyoko Nakanishi, Makoto Nakajima, Takehisa Kunieda, and Tadao Ishizuka*

*Faculty of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Kumamoto 862-0973, Japan

Abstract

Highly enantioselective transfer hydrogenation of ketimines to the corresponding chiral amines was achieved with the chiral Ru(II) complex, prepared from the conformationally rigid and sterically bulky “roofed” cis-1,2-diamine.

■ A Convenient Method of Preparation of 3,3’-Dichloro-5,5’-bi-1,2,4-triazine and Its Synthetic Applications

Ewa Wolińska*

*Department of Chemistry, University of Podlasie, ul. 3-go Maja 54, 08-110 Siedlce, Poland

Abstract

A convenient method for preparing of 3,3'-dichloro-5,5'-1,2,4-triazine (4) and its application to the synthesis of 3,3'-diamino-5,5'-bi-1,2,4-triazines 6a i by the nucleophilic aromatic substitution are described. An attempt to synthesis of cyclophanes containing 5,5'-bi-1,2,4-triazine subunit by ring-closing metathesis of the alkenyl ethers 7a,b have been unsuccessful. A crossover experiment clearly shows that nitrogen atoms of the 1,2,4-triazine ring coordinate to the ruthenium catalyst and deactivate it.

■ Efficient Syntheses of 1-Azatricyclic Ring Systems from Anthranylamide

Daniele Muroni, Mauro Mucedda, and Antonio Saba*

*Department of Chemistry, University of Sassari, Via Vienna 2, I-07100 Sassari, Italy

Abstract

Concise syntheses of novel tricyclic quinazolinone and pyrrolo benzoazacyclononenone alkaloids in two and three steps (two pots), starting from 3-styryl quinazolinone, by utilizing RCM and cascade spiro-to fused protocols, respectively, were reported.

■ Copper(I)-Catalyzed Direct Arylation of 1,4-Disubstituted 1,2,3-Triazoles with Aryl Iodides

Shin-ichi Fukuzawa,* Eiji Shimizu, and Kenichi Ogata

*Faculty of Science and Engineering, Chuo University, , Japan

Abstract

Treatment of 1,4-disubstituted 1,2,3-triazoles with aryl iodides in the presence of a catalytic amount of copper chloride and lithium tert-butoxide (stoichiometric) in DMF at 140 °C leads to arylation at the 5-position. Various combinations of substituted aryl iodides and 1,4-disubstituted 1,2,3-triazoles bearing functional groups were found to be compatible.

■ Novel Reactions of Steric Encumbered 1,4-Dilithio-1,3-butadiene with Group 14 Electrophiles: Formation and Structure of Stable Dihydroxygermole

Masaichi Saito,* Michio Nakamura, and Tomoyuki Tajima

*Saitama University, Shimo-okubo, Sakura-ku, Saitama 338-8570 , Japan

Abstract

Reactions of 1,4-dilithio-1,3-butadiene 1 having bulky silyl ligands at the 1,4-positions with group 14 electrophiles were examined. Reactions of 1,4-dilithio-1,3-butadiene 1 with tetraethoxygermane gave diethoxygermole 5, which was hydrolyzed to give stable dihydroxygermole 16. The X-ray diffraction analysis of dihydroxygermole 16 revealed intermolecular hydrogen bonds. The reaction of 1 with stannous chloride was also examined.

■ Synthesis of 1H-Isoindol-3-amine Derivatives by Iodine-Mediated Cyclization of 2-Vinylbenzamidine Derivatives

Kazuhiro Kobayashi,* Mai Horiuchi, Shuhei Fukamachi, and Hisatoshi Konishi

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

Abstract

It has been found that the reaction of 2-vinylbenzamidine derivatives, prepared by reacting 2-vinylbenzonitriles with lithium cyclic secondary amides, with iodine in the presence of sodium hydrogen carbonate in acetonitrile resulted in the formation of the corresponding 1-iodomethyl-1H-isoindole-3-amine derivatives in reasonable overall yields based on the starting 2-vinylbenzonitriles. We have also found that transformation of these 1-iodomethyl derivatives into 1-sulfenylmethyl derivatives could be achieved in good yields on treatment with various sodium thiolates.

■ First Entry to [4+2] Cycloadditions Involving 5-Amino-2-furanmethanols

Raouf Medimagh, Sylvain Marque,* Damien Prim,* and Saber Chatti

*Institut Lavoisier de Versailles, UMR CNRS 8180, University of Versailles-Saint-Quentin-en-Yvelines, 78035 Versailles Cedex, France

Abstract

The preparation of new 5-amino-2-furanmethanols bearing various amino and primary or secondary alcohol groups is described. The structures of 5-amino-2-furanmethanols as dienes are consistent with 1H NMR data and cyloadditions of them allows the selective synthesis of tetrasubstituted aminobenzylic alcohols, amino phenols or lactones through Diels–Alder reactions.

■ Synthesis of Nitrogen-Containing Heterocycles 12. Reactions of 2-Amino-1-benzylideneamino-1H-imidazoles with Dimethyl Acetylenedicarboxylate

Yoshiko Miyamoto*

*Department of Chemistry, School of Science, Kitasato University, 1-15-1, Kitasato, Sagamihara, Kanagawa 228-8555, Japan

Abstract

2-Amino-4-aryl-1-benzylideneamino-1H-imidazoles (1) reacted with dimethyl acetylenedicarboxylate (DMAD) in benzene to give dimethyl 2-amino-1-benzylidene-amino-1H-pyrrole-3,4-dicarboxylates (3), benzonitriles (4) and dimethyl 1-(2-amino-1-benzylideneamino-4-aryl-1H-imidazole-5- yl)fumarates (5) in moderate to high yields. Compounds 3 and 4 were considered as the reaction products of the intermediary Diels-Alder adducts, dimethyl 1-amino-3-aryl-7-benzylideneamino-2,7-diazabicylo[2.2.1]hepta-2,5-diene-5,6-di-carboxylates (2), which were not isolated and decomposed in a retro Diels-Alder reaction. The products 5 resulted from a Michael conjugate addition reaction of 1 to DMAD.

■ An Efficient Single Step Synthesis of Pyridazine, Pyrazolo[5,1-c]-1,2,4-triazine, 1,2,4-Triazolo[5,1-c]-1,2,4-triazine and 1,2,4-Triazino[4,3-a]benzimidazole Derivatives

Mohamed R. Shaaban, Tamer S. Saleh, and Ahmad M. Farag*

*Department of Chemistry, Faculty of Science, University of Cairo, Giza 12613, Egypt

Abstract

Coupling of E-1-(1-methylbenzimidazol-2-yl)-3-(N,N-dimethylamino)prop-2-enone (1) with the arenediazonium salt gave hydrazonopropanal 5 which underwent cyclocondensation with active methylene compounds to afford substituted pyridazin-6-imine 8 and 11. The enaminone 1 coupled also with the diazonium salts prepared from aminopyrazole, aminotriazole and 2-amino-1H-benzimidazole to afford pyrazolo[5,1-c]-[l,2,4]-triazine 15, 1,2,4-triazolo[5,1-c]-[1,2,4]-triazine 19, 1,2,4-triazino[4,3-a]benzimidazole 23 derivatives, respectively.

■ The Cleavage of Heterocyclic Compounds IV. Study of the Reactivity of the [1]Benzothieno[2,3-e][1,2,4]triazine System towards Nucleophilic Reagents

Jiří Filipčík, Jakub Stýskala,* and Jan Slouka

*Department of Organic Chemistry, Palacky University, Trida Svobody 8, 77146 Olomouc, Czech Republic

Abstract

A series of 5-substituted 1,2,4-triazines were prepared by nucleophilic cleavage of the thiophene ring of [1]benzothieno[2,3-e][1,2,4]triazine 1 with some nitrogen, oxygen, sulfur and carbon containing nucleophilic agents. The thiophene ring of compound 1 was transformed by oxidative cleavage to the corresponding sulfonic acid 10.

■ One Pot Synthesis of Optically Active 4-Isoxazolines by Asymmetric Addition of Alkynylzinc Reagents to Nitrones Followed by Cyclization

Weilin Wei, Masato Kobayashi, Yutaka Ukaji,* and Katsuhiko Inomata*

*Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan

Abstract

One pot synthesis of optically active 4-isoxazolines was achieved by asymmetric addition of alkynylzinc reagents to nitrones utilizing di(t-butyl) (R,R)-tartrate as a chiral auxiliary followed by cyclization. By addition of dimethylzinc, the cyclization step was accelerated to afford the corresponding 4-isoxazolines with up to 93% ee. Furthermore, a cyclized zinc intermediate could be trapped with formaldehyde to give the corresponding 2,3,4,5-tetrasubstituted 4-isoxazoline with 85% ee.

■ A Facile Approach to Indolizines via Tandem Reaction

Yan-Qing Ge, Jiong Jia, He Yang, Gui-Long Zhao, Fu-Xu Zhan, and Jianwu Wang*

*School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, China

Abstract

Indolizines were synthesized by a novel tandem reaction at rt. The operation was simple and convenient. Various indolizine derivatives were obtained in good yields. The reaction mechanism was also proposed.

■ On the Photoisomerization of Thiophene and Thiazole Derivatives

Maurizio D'Auria* and Rocco Racioppi

*Department of Chemistry, University of Basilicata, Via N. Sauro 85, 85100 Potenza, Italy

Abstract

The photochemical isomerization of thienyl and thiazolyl derivatives can be explained by assuming the formation of the Dewar isomer. The isomerization of the Dewar isomer towards the most stable one can account for the observed reaction. No biradical intermediate was found. In the case of thiophene an isomerization of the Dewar thiophene allows the formation of a tricyclic intermediate; a retroelectrocyclic reaction can afford the reaction product. This tricyclic intermediate cannot be formed in the photoisomerization of thiazole derivative.

■ Concise Synthesis of Xyloketal C Analogues

Yan Huang and Yong-Cheng Lin*

*School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China

Abstract

The synthesis of xyloketal C analogues 12-methylxyloketal C(8) and 12-dehydroxylxyloketal C(11) have been accomplished in three steps, which featured the radical cyclisation as the key step. This is the shortest approach to construct the B C ring systems of the type of ketal skeleton reported to date. The structures of title compounds were elucidated by spectroscopic data and X-ray structure analysis. The final radical cyclisations give mainly the cis-fused anti-substituted stereoisomers.

■ A Convenient Synthesis of 5-Arylidenethiazolidine-2,4-diones Catalyzed by Alkaline Ionic Liquid

Yi Hu, Tao Xie, Kai-Mei Fu, Hui Kang, Ping Wei, and He Huang*

*State Key Laboratory of Materials-Oriented Chemical Engineering, College of Life Science and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing Xin Mofan Road 5, Nanjing 210009, China

Abstract

A series of 5-arylidenethiazolidine-2,4-diones was synthesized by the Knoevenagel condensation of thiazolidine-2,4-dione with aromatic aldehydes with alkaline ionic liquid 1-butyl-3-methylimidazolium hydroxide ([bmim]OH) as dual solvent and catalyst. This method provides many advantages such as being environmentally benign, simple work-up, short reaction times, obtaining in good to excellent yields, and the reusability of ionic liquid.

■ Chemical Constituents from the Leaves of Xylopia poilanei and Their Bioactivity

Tran Dinh Thang, Ping-Chung Kuo, Ngo Xuan Luong,* Nguyen Xuan Dung, Le Van Hac, Yao-Haur Kuo, Mei-Lin Yang, and Tian-Shung Wu*

*Department of Chemistry, National Cheng Kung University, 1, Ta-Shiueh Rd., Tainan 70101, Taiwan, R.O.C.

Abstract

A new flavonoid glycoside, xylopoillin A (1), and nine known compounds were isolated from the methanolic extracts of the leaves of Xylopia poilanei. The structure of this new compound was completely elucidated using a combination of 2D NMR techniques (COSY, NOESY, HMQC and HMBC) and HR-ESI-MS analyses. The other chemical structures of known compounds were identified by comparison of their spectroscopic and physical data with those reported in the literature.

■ An Efficient Synthesis of 1-Acyl-3-arylimidazolidines Catalyzed by Montmorillonite K-10 Clay under Microwave Irradiation

María Cristina Caterina, María Verónica Corona, Isabel Perillo, and Alejandra Salerno*

*Proyecto UBA B-104, Junín 956, Buenos Aires, Argentina

Abstract

The synthesis of 1-acyl-3-arylimidazolidines were performed by reaction of N-acyl-N´-arylethylenediamines with formaldehyde and Montmorillonite clay K-10 as a catalyst under microwave irradiation.