DOI: 10.1002/asia.200700149 Enantiopure Double-Helical Phenylene Ethynylene Cyclophynes with the 2,2’-Binaphthyl Template De-Lie An,* [a] Ying-Jun Zhang, [a] Qiang Chen, [a] Wen-Ying Zhao, [a] Hong Yan, [a] Akihiro Orita, [b] and Junzo Otera* [a, b] Introduction Modern cyclophane chemistry has witnessed great advances in its acetylenic family, cyclophynes, in the context of grow- ing interest in carbon-rich materials and shape-persistent macrocyclic molecules. [1] In particular, numerous aromatic cyclophynes have appeared owing to rapidly developed technology for the synthesis of aromatic acetylenes. Some of these molecules are chiral but, unfortunately, obtained as racemates except for only a few. [2] Previously, we synthe- sized double-helical cyclophynes composed of meta-connect- ed phenylene ethynylene frameworks with 2,2’-binaphthyl templates such as (R,P)-1a and -1b. [3] The CD spectra of these molecules displayed dramatic variations of the Cotton effect that depended on ring size, thus implying that molecu- lar chirality, once enantiopure materials have been acquired, can provide a probe for the persistency of molecular shape. Accordingly, we were intrigued by the design of other cyclo- phynes with double helicity in enantiopure form. In phenyl- ene ethynylene cyclophynes, the substitution pattern of the aromatic rings directs the orientation of the acetylenic bonds, thereby defining the molecular structure and its per- sistency. In this study, the ortho connection of the ethynyl groups on the phenylene ring was newly taken into account to give (R,P)-2 and -3. Furthermore, a diphenylethyne com- ponent was also accommodated to provide (R,P)- and (S,M)-4. The shape persistency of these compounds, togeth- er with 1 for comparison, will be discussed on the basis of the NMR and CD spectra. Resuls and Discussion The synthesis of (R,P)-2 and -3 is shown in Scheme 1. meta- Substituted phenylethynyl compounds 8a and 9a were pre- pared according to our previous method. [3] The correspond- ing ortho-substituted derivatives, 8b and 9b, were obtained analogously. Desilylation of 8a and 8b afforded meta- and ortho-triazenes 10a and 10b, respectively. Next, coupling of 9a or 9b with 10b afforded 11a or 11b. Conversion of tri- Abstract: New types of enantiopure compounds were synthesized to gain better insight into the structural fea- tures of phenylene ethynylene cyclo- phynes. Besides the previously ob- tained meta-substituted arylene ethyn- ACHTUNGTRENNUNGylenes, 1, ortho-connected phenylene ethynylene units were incorporated to give cyclophynes with ortho/meta and ortho/ortho connection modes, 2 and 3. Furthermore, a diphenylethyne compo- nent was also accommodated in 4. Both ab initio calculations and NMR spectra suggest a large amount of strain for 2 but less strain for 3 and 1a, the latter having the smallest ring size among cyclophynes with the meta/meta connection mode. The CD spectra of 2 and 3 showed a characteristic shoulder at around 340 nm, similar to the case of 1a. This implies that the aromatic acetylene bonds cross over each other in the double-helical structure. These results indicate that chirality informa- tion is useful for probing the persisten- cy of molecular shape. Keywords: acetylenes · chirality · cyclophanes · cyclophynes · helical structures [a] Prof. Dr. D.-L. An, Y.-J. Zhang, Q. Chen, W.-Y. Zhao, H. Yan, Prof. Dr. J. Otera Department of Chemistry College of Chemistry and Chemical Engineering Hunan University, Changsha 410082 (China) Fax: (+86)731-882-1308 E-mail: deliean@sina.com [b] Prof. Dr. A. Orita, Prof. Dr. J. Otera Department of Applied Chemistry Okayama University of Science Ridai-cho, Okayama 700-0005 (Japan) Fax: (+ 81)86-256-4292 E-mail: otera@high.ous.ac.jp Supporting information for this article is available on the WWW under http://www.chemasianj.org or from the author. Chem.AsianJ. 2007, 2, 1299–1304 # 2007 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim 1299