HETEROCYCLES

■ Contents

■ Synthesis of Rhazinilam: A Comparative Review of Forty Years of Synthetic Endeavors

Inga Kholod, Olivier Vallat, Ana-Maria Buciumas, and Reinhard Neier*

*Department of Chemistry, University of Neuchâtel, Avenue de Bellevaux 51, Case Postale 2, CH-2007 Neuchâtel, Switzerland

Abstract

R-(-)-Rhazinilam is a relatively simple but unusual monopyrrolic product isolated from nature. It is probable that R-(-)-rhazinilam is an artifact of the isolation procedure. Seven total syntheses of rhazinilam have been described in the literature. The comparison of the published syntheses clearly demonstrates the sensitivity of the pyrrole ring contained in the rhazinilam structure. Despite the spectacular progress in organic synthetic methods only a few synthetic strategies have been applied to the total synthesis of rhazinilam. Astonishingly the number of steps needed from commercial starting materials has stayed similar over the almost 40 year period since the first synthesis has been reported in 1973.

■ Development and Applications of an Oxazole-Forming Reaction

Jianmin Zhang,* Pierre-Yves Coqueron, and Marco A. Ciufolini*

*Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver B.C., V6T 1Z1, Canada

Abstract

We review an oxazole-forming reaction devised in our laboratory. The technique allows the facile assembly of 2,5-disubstituted-4-carbalkoxy oxazoles, including 5-amino and 5-alkenyl oxazoles. Applications of this chemistry in the total synthesis of muscoride A, siphonazoles, and other oxazole alkaloids are described.

■ Properties and Bioactivities of Peptoids Tagged with Heterocycles

Irene Izzo, Chiara De Cola, and Francesco De Riccardis*

*Department of Chemistry, University of Salerno, Via Ponte don Melillo, I-84084 Fisciano (SA), Italy

Abstract

N-substituted oligoglycines, also called “peptoids”, form a major class of pseudopeptides encompassing a wide range of structures and properties. Their inherent features make them useful in areas as diverse as medicinal chemistry, catalysis, and molecular recognition. In this review, the authors, with selected examples, show the wide range of properties of oligomeric peptoids tagged with heterocycles. It is also revealed how the imaginative structures created by synthetic chemists are exciting and varied, and, in which terms, their potential has just started to be addressed.

■ Indole Chemistry for Combating Yellow Sand and Desertification Directed towards Stopping Global Warming

Masanori Somei*

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

Abstract

Various derivatives of indole-3-carbaldehyde are found to be root regulators and they are named SOMRE compounds. Since some of them are potent root promoters and make roots three times longer than usual, their possibilities for increasing food production, combating yellow sand and desertification in Gobi desert, China, were examined. All preliminary experiments are thus far working well. For greening desert and stopping the global warming, it is vital importance to sow seeds to vast area of sand dune all at once. We are now on the stage to scatter seeds, pretreated with SOMRE, to sand dune by airplane.

■ 4-Alkynoic Acids in the Synthesis of Biologically Important Tetrapyrroles

Peter A. Jacobi,* Harry L. Brielmann, Melanie Chiu, Indranath Ghosh, Sheila I. Hauck, Sandra Lanz, Sam Leung, Yongkai Li, Hui Liu, Franzisca Löwer, William G. O’Neal, Douglas Pippin, Elizabeth Pollina, Benjamin A. Pratt, Frédéric Robert, William P. Roberts, Carlos Tassa, and Hui Wang

*6128 Burke Laboratory, Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, U.S.A.

Abstract

In this review an account is given of the author's use of 4-alkynoic acid derivatives in the synthesis of members of the chlorin, bacteriochlorin and corrin classes of macrocyclic tetrapyrroles. In the case of chlorins, we employed a novel "2+2" condensation to prepare both C,D-symmetric and non-symmetric chlorins, made possible by the ready availability of semicorrins of type 25 derived from 4-alkynoic acids 1. Alkyne acids 1 also played a prominent role in a new 16π-electrocyclization route to bacteriochlorins, and in iterative syntheses of semicorrins and secocorrins related to vitamin B12. Mechanistic studies provided insight into the nature of these Pd(0)-catalyzed coupling/cyclization reactions. Finally, we describe enantioselective syntheses of ring-C and ring-D alkyne acids for an ongoing synthesis of cobyric acid.

■ Further Application of the Multi-Template Approach for Creation of Biological Response Modifiers: Discovery of a New Class of Multifunctional Anti-Diabetic Agents

Kazunori Motoshima, Tomomi Noguchi-Yachide, Minoru Ishikawa, Yuichi Hashimoto, and Kazuyuki Sugita*

*Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan

Abstract

We have previously employed the multi-template approach to create many types of biologically active compounds. In this review, we focus on extension of the multi-template approach to develop candidate anti-diabetic and anti-metabolic syndrome agents with a well-balanced range of activities.

■ Unexpected Formation of Dihydrobenzosilole Derivative via the Intramolecular Cyclization in the Reaction of Overcrowded Dichloromethylsilane with Aryllithium

Takahiro Sasamori,* Eiko Mieda, and Norihiro Tokitoh*

*Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan

Abstract

The reaction of overcrowded aryldichloromethylsilane 1 bearing a 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt) group with an excess amount of XylLi or MesLi (Xyl = 2,6-xylyl, Mes = mesityl) unexpectedly afforded the corresponding dihydrobenzosilole derivative 2 together with silyl-migrated olefin 3. The generation of 2 in this reaction is most likely interpreted in terms of intermediacy of 1,2-dihydro-2-chlorosilene 4.

■ Concise Substrate-Controlled Asymmetric Total Synthesis of (+)-3-(Z)-Dihydrorhodophytin

Byungsook Kim, Te-ik Sohn, Sanghee Kim, Deukjoon Kim,* and Jongkook Lee

*The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Shillim-Dong, San 56-1, Kwanak-Gu, Seoul 151-742, Korea

Abstract

The first asymmetric total synthesis of (+)-3-(Z)-dihydrorhodophytin (1) has been accomplished in 15 steps in 17% overall yield from readily available starting material 6 in a substrate-controlled manner. Key steps in our synthesis are a highly stereoselective dianion alkylation for the synthesis of the α,α’-anti-RCM substrate and a strategy for the introduction of the chlorine function.

■ Modification of D-Ring Moiety of Steroids − A Novel Palladium Catalyzed Baeyer-Villiger Type Rearrangement of Cyclic Silylenol Ether Derivatives

Minoru Tamiya,* Futa Takada, Nobuhisa Isaka, Nahoko Iimura, and Masaji Ishiguro*

*Chemical Biology Laboratory, Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, 265-1, Higashijima, Niigata 956-8603, Japan

Abstract

A novel Baeyer–Villiger type rearrangement reaction of cyclic silylenol ether derived from dehydroepiandrosterone via oxygen and catalytic amount of palladium acetate in the presence of DMSO has been developed. The reaction proceeded at low temperature and high pressure of oxygen to afford corresponding α,β-unsaturated lactones in moderate yields.

■ Asymmetric Synthesis of (+)-Machilin F by Unusual Stereoselective Mitsunobu Reaction

Kenichi Harada, Naoko Kubo, Kazuma Tanabe, Miwa Kubo, Tomoyuki Esumi, Hideaki Hioki, and Yoshiyasu Fukuyama*

*Faculty of Pharmaceutical Sciences, Tokushima Bunri University, 180 Nishihamabouji, Yamashiro-machi, Tokushima, 770-8514, Japan

Abstract

First synthesis of (+)-machilin F (1c) has been achieved in 16 steps as part of systematic synthetic studies on (−)-talaumidin (1) and its stereoisomers. The 2,3,4,5-tetrasubstituted tetrahydrofuran with the (2S,3S,4R,5R)-configuration has been constructed stereoselectively from diol 14 by Mitsunobu reaction.

■ Unprecedented Synthesis of N,N-Divinylamines by Tf2NH-Catalyzed Reaction of Ynamide with Ketimine

Naoya Shindoh, Yoshiji Takemoto,* and Kiyosei Takasu*

*Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-shimoadachi-machi, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

Tf2NH-catalyzed synthesis of N,N-divinylamines from ynamides and acetophenoneimines is described. The products would be produced through the formation of the corresponding keteniminiums and enamines by the assistance of the catalyst.

■ Hexamethyldisilazane-Promoted Sonogashira Reaction of Polyfunctionalized N-Containing Heterocycles

Masahiko Inouye,* Yasuhiro Doi, Junichi Azuchi, Wataru Shirato, Junya Chiba, and Hajime Abe*

*Laboratory of Chemical Biology, Faculty of Pharmaceutical Sciences, Toyama University, 2630 Sugitani, Toyama 930-0194, Japan

Abstract

1,1,1,3,3,3-Hexamethyldisilazane (HMDS) was found to be an efficient solvent for Sonogashira reaction. For the synthesis of C-nucleosides, Sonogashira reaction of ethynyldeoxyriboside with halogenated pyrimidine or pyridine derivatives could be improved by the use of an HMDS−DMF mixed solvent. In situ protection of hydroxy and amino groups by the solvent system may play an important role for the improvement.

■ McMurry Coupling of Diformyldithienylacetylene: Synthesis of [24]-, [36]-, and [48]Annulenes Composed of Thiophene, Acetylene, and Ethylene Units

Masahiko Iyoda,* Pochi Huang, Tomohiko Nishiuchi, Masayoshi Takase, and Tohru Nishinaga

*Graduate School of Science, Tokyo Metropolitan University, 1-1, Minami-ohsawa, Hachioji, Tokyo 192-0364, Japan

Abstract

The reaction of diformyldithienylacetylene 4 with a McMurry reagent prepared from TiCl4, Zn, and pyridine in THF afforded 24π-dimer 1b (15%), 36π-trimer 2b (13%), and 48π-tetramer 3b (6%). From X-ray analysis, 1b adopts a twisted conformation, although the 1H NMR spectrum of 1b shows a symmetrical structure owing to a rapid conformational change in solution. Absorption and emission spectra, redox properties, and electric conductivities of 1b–3b were measured in order to study the structure–property relationship of these macrocyclic systems.

■ Synthesis of Antioxidant Flavonoid Derivatives

Emiko Yanase, Young P. Jang, and Koji Nakanishi*

*Centennial Professor of Chemistry Emeritus, Department of Chemistry, Columbia University, 3000 Broadway, MC 3144, New York, NY 10027, U.S.A.

Abstract

Quercetin-caffeic acid and quercetin-curcumin conjugates have been synthesized as potent antioxidants to prevent age-related macular degeneration. Thus, the widely disributed plant antioxidant quercetin was linked to other plant antioxidants, caffeic acid and curucumin, to enhance its antioxidative properties.

■ Oxidation of Pyrrole-2-carboxylates with o-Chloranil and Its Synthetic Application

Ryo Sakata, Ryoji Iwamoto, Shuhei Fujinami, Yutaka Ukaji,* and Katsuhiko Inomata*

*Chemistry Course, College of Science and Engineering, School of Chemistry, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan

Abstract

t-Butyl 3,4-dialkyl-1H-pyrrole-2-carboxylates were oxidized with o-chloranil in the presence of MeOH to afford the corresponding 5-methoxypyrrolin-2-one derivatives. The resulting 5-methoxypyrrolin-2-one was reacted with various nucleophiles under acidic conditions to afford the functionalized pyrrolinone derivatives in good yields.

■ [2,3] Wittig Rearrangement of β’-Hydroxyethyl Bis-Allylic Ethers: Highly Regiospecific Entry to Singly Dehydroxylated 19-Nor-1(or 3),25-dihydroxy-vitamin D3

Koichi Mikami,* Kumiko Fujita, Kazuki Wakabayashi, and Shigekazu Ito

*Department of Applied Chemistry, Graduate School of Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan

Abstract

A conceptually new approach to regiospecific deprotonation at the α-position of β'-hydroxyethyl bis-allylic ethers is shown on the basis of the dianion repulsion with the β'-alkoxy anion, of which the [2,3]Wittig rearrangement product can be transformed to the A-rings of singly dehydroxylated 1(or 3),25-dihydroxy-19-nor-vitamin D3 analogues to stimulate apoptosis or differentiation of HL-60 cancer cell.

■ Kinetic Resolution of the Racemic 1-(Aryloxazol-2-yl)carbinols with Achiral Carboxylic Acids by Asymmetric Esterification: A New Method for the Preparation of Chiral 1,2-Amino Alcohols

Kenya Nakata, Keisuke Ono, and Isamu Shiina*

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

Abstract

An efficient kinetic resolution of racemic 1-(aryloxazol-2-yl)carbinols with achiral carboxylic acids using pivalic anhydride in the presence of (R)-benzotetramisole ((R)-BTM) is reported. It was determined that the naphth[1,2-d]oxazole moiety at the C-1 position in the alcohols is a suitable structure to attain a high selectivity. An application to produce optically pure 1,2-amino alcohols was developed by the kinetic resolution of the racemic 1-(aryloxazol-2-yl)carbinols followed by a two-step cleavage of the aryloxazole part to form the corresponding amino group. Transition states that provide the desired (R)-esters from (R)-1-(benzoxazol-2-yl)ethan-1-ol or the undesired (S)-esters from (S)-1-(benzoxazol-2-yl)ethan-1-ol are disclosed by DFT calculations. Another transition state that affords the desired (R)-ester from (R)-1-(naphth[1,2-d]oxazol-2-yl)ethan-1-ol included in the racemic mixture is also estimated, and the structural features of these transition states are discussed.

■ Asymmetric Synthesis of γ-Siloxyenamides via Chiral Auxiliary-Mediated Diastereoselective Coupling of Ynamides, Aldehydes, and Silane by Nickel Catalyst

Nozomi Saito, Tomoyuki Katayama, and Yoshihiro Sato*

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

Abstract

A nickel-catalyzed diastereoselective three-component coupling of optically active oxazolidinone-derived ynamides, aldehydes, and silane is described. The reaction proceeded via stereoselective formation of oxanickelacycle to give γ-siloxyenamide derivatives in a highly diastereoselective manner.

■ Hydrogen-Activated Benzylidynetricobalt Nonacarbonyl: Carbonylative Cyclization of Enynes in Synthesis Gas without Reducing Substrates and Products

Takumichi Sugihara,* Akihito Wakabayashi, Mugio Nishizawa, and Shinobu Honzawa

*Niigata College of Pharmacy, 265-1, Higashi-jima, Niigata 956-8603, Japan

Abstract

Benzylidynetricobalt nonacarbonyl was activated by hydrogen and catalyzed the carbonylative cyclization of enynes without reducing substrates and products.

■ Nucleophilic Reactions of 9-Isopropyl-2,4-dimethoxy-7,12-dimethyl-3-(phenylsulfonyl)benzo[a]heptalene with Lithium Dialkylamides

Samir El Rayes, Anthony Linden, Khaled Abou-Hadeed, and Hans-Jürgen Hansen*

*Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

Abstract

Treatment of the title compounds with lithium piperidinide in THF at –5 °C leads to an exchange of the two methoxy groups by piperidino substituents (Scheme 2). On the other hand, lithium diisopropylamide (LDA) in THF at –5 °C induces the formation heptaleno-annulated dibenzothiophenes.

■ Autocatalysis and Organocatalysis with Kemp’s Triacid Compounds

Dariush Ajami, Seiji Kamioka, Aaron C. Sather, Richard J. Hooley, and Julius Rebek, Jr.*

*Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, U.S.A.

Abstract

Synthetic structures capable of autocatalysis based on molecular recognition – self-replication – were introduced nearly 20 years ago. These systems involved neither informational oligomers such as nucleic acids nor conditions that are generally regarded as prebiotic, but they revealed how self-complementary molecules could act as templates for their own formation and helped define the structure of minimalist replicators. Recent expansions in the field of organocatalysis raise the possibility that a synthetic structure might behave as an autocatalyst and function as a chemical catalyst for other reactions. We show here that these properties can be engineered into a single synthetic structure: the compound can selectively accelerate its own formation and catalyzes hydrogenation reactions of nitrostyrene. It is likely that a wide variety of synthetic structures can be modified for autocatalysis and organocatalysis.

■ 2-Amino-3-(5-phenylfuran-2-yl)propionic Acids and 5-Phenylfuran-2-ylacrylic Acids are Novel Substrates of Phenylalanine Ammonia-Lyase

Csaba Paizs, Monica Ioana Toşa, László Csaba Bencze, Jürgen Brem, Florin Dan Irimie, and János Rétey*

*Institute of Organic Chemistry, Karlsruhe Institute of Technology , Richard-Willstätter-Allee, D-76128 Karlsruhe, Germany

Abstract

Both racemic 2-amino-3-(5-phenylfuran-2-yl) propionic acids and 5-phenylfuran-2-yl acrylic acids were synthesized and spectroscopically characterized (UV, EI-MS, 1H-NMR and 13C-NMR). The phenyl group of the 5-phenylfuranyl residue carried no (rac-1a) para-Br (rac-1b) or Cl para or ortho (rac-1c, d) substituents. The novel furanylalanines were used as substrates of recombinant phenylalanine ammonia-lyase (PAL). When 50% of the racemic 5-phenylfuranyl-alanines were converted into the corresponding acrylates, the D-enantiomers of the substrates could be isolated. The L-enantiomers could be prepared from the substituted acrylates when the PAL reaction was reversed in the presence of 6 M ammonia at pH 10.

■ Preparation and Electrochemical Properties of Phthalocyaninato Titanium (IV) and Porphyrinato Titanium (IV) Benzenedichalcogenolates

Takeshi Kimura,* Kaori Amano, Arata Yamamoto, and Toshiharu Namauo

*Center for Instrumental Analysis, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan

Abstract

The reaction of phthalocyaninato titanium (IV) oxides with benzenedithiol or benzenediselenol produced the corresponding complexes with titanium-sulfur or titanium-selenium bonds. Tetraphenylporphyrinato titanium (IV) benzenedichalcogenolates were obtained by the similar procedure. Their optical and electrochemical properties were determined by UV-vis spectroscopy and cyclic voltammetry.

■ Generation of 3-(1H-Isochromen-1-yl)-1H-indole via Silver Triflate-Catalyzed Tandem Reaction of 2-Alkynylbenzaldehyde with Indole

Banlai Ouyang, Jianjun Yuan, Qin Yang, Qiuping Ding, Yiyuan Peng,* and Jie Wu*

*Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433, China

Abstract

A facile and efficient method is developed for synthesis of 3-(1H-isochromen-1-yl)-1H-indole via silver triflate-catalyzed tandem reaction of 2-alkynylbenzaldehyde with indole. The reaction proceeds smoothly in DMF at room temperature with good substrate generality. The availability of the starting materials combined with mild reaction conditions and the high efficiency of this synthetic route would be attractive and beneficial for the focused library construction.

■ A New Synthetic Approach to Some Functionalized Cycl[3.2.2]azine Derivatives

Hideyuki Muranaka, Akikazu Kakehi,* Hiroyuki Suga, and Kennosuke Itoh

*Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan

Abstract

Dehydrogenation of some ethyl 4-oxo-1H-8,8a-dihydro-1,4- thiazino[3,4,5-cd]indolizine-1-carboxylates with 2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ) were examined. No simply dehydrogenated products such as 4-oxo-1H- and 4-oxo-8H-1,4-thiazino[3,4,5-cd]indolizines or their full conjugated enol forms could be obtained, but ethyl cycl[3.2.2]azine-1- carboxylates were directly obtained via the cyclization and the subsequent desulfurization of the 4H-1,4-thiazine ring in the dehydrogenated intermediates.

■ N-Methyl-N-phenyl-5-oxa-1-azaspiro[2.5]oct-1-en-2-amine — Synthesis and Reactions of a Synthon for an Unknown α-Amino Acid

Michael Löpfe, Anthony Linden, and Heinz Heimgartner*

*Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

Abstract

The synthesis of the heterospirocyclic amino azirine N-methyl-N-phenyl-5-oxa-1-azaspiro[2.5]oct-1-en-2-amine (6a) was achieved from 3,4-dihydro-2H-pyrane (7) via N-methyl-N-phenyltetrahydropyran- 3-thiocarboxamide (11). The reactions of 6a with thiobenzoic acid and Z-Phe-OH, respectively, leading to the corresponding 3-benzoylaminotetrahydropyran- 3-thiocarboxamide (13) and the diastereoisomeric dipeptide amides (14), respectively, demonstrate that 6a is a valuable synthon for the hitherto unknown 3-aminotetrahydropyrane-3-carboxylic acid. The structure of 13 was established by X-Ray crystallography.

■ 2-[1,3-Bis(ethoxycarbonyl)azulen-6-yl]ethynyltriphenylphosphonium Bromide

Noboru Morita,* Shiro Moriyama, Kozo Toyota, Masataka Watanabe, Shigeru Kikuchi, Shunji Ito, and Kunihide Fujimori

*Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan

Abstract

2-[1,3-Bis(ethoxycarbonyl)azulen-6-yl]ethynyltriphenylphosphonium bromide was prepared from diethyl 6-ethynyl-1,3-azulenedicarboxylate. Its NMR spectroscopic property was made clear. Furthermore, its reactivity with o-substituted aniline was studied, comparing with 1- and 2-ethynyl azulene derivatives. We found that 2-[3-(methoxycarbonyl)azulen-1-yl]ethynyltriphenyl- phosphonium bromide also reacted with o-substituted anilines in CHCl3 to give corresponding 2-[1,3-bis(ethoxycarbonyl)azulen-6-yl]benzoazoles. However, in DMSO another products were obtained.

■ Synthesis of Highly Substituted Nitropyrrolidines, Nitropyrrolizines and Nitropyrroles via Multicomponent-Multistep Sequences within a Flow Reactor

Marcus Baumann, Ian R. Baxendale, Andreas Kirschning, Steven V. Ley,* and Jens Wegner

*Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge
CB2 1EW, U.K.

Abstract

We expand upon recent results concerning dipolar cycloaddition reactions of unstabilized azomethine ylids with nitro alkenes to generate 3-nitropyrrolidines via a flow chemistry sequence. This new work describes the development of a three-component coupling reaction between glycine esters, aldehydes and nitro alkenes. In order to further demonstrate the utility of flow technology in concert with heterogeneous reagents and scavengers for complex reaction sequences an in-line oxidation resulting in the conversion of tetra-substituted pyrrolidines to their pyrrole congeners has been developed.

■ Synthesis and Properties of N 1-(3-Methoxypropyl)-N 3-methylimidazolium Salts

Eigo Miyazaki,* Nozomi Ishine, Kazuo Takimiya,* and Hiroyuki Kai

*Chemistry and Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8527, Japan

Abstract

N1-(3-Methoxypropyl)-N3-methylimidazolium salts (1c–1f) were synthesized and characterized. The N(SO2CF3)2– salt (1c) exhibited the lowest viscosity (51 cP) among the salts (1c–1f). The I– salt (1d) was tested as an electrolyte solution to the dye-sensitized solar cells (DSSCs), and the devices worked as the DSSCs.