Synthesis and Properties of Cationic π-Conjugated Systems Stabilized by Bicyclo[2.2.2]octene Units

Abstract

The purpose of this Account is to present the results of our systematic study on the synthesis of a series of cyclic π-conjugated systems with the monocyclic six-membered to eight-membered rings as well as polycyclic aromatic compounds, which are fully surrounded by rigid bicyclic σ-frameworks. This structural modification is characteristic in causing elevation of the HOMO levels of neutral π-systems and remarkably stabilizing the corresponding cationic systems by both thermodynamic and kinetic effects. In order to minimize the possible steric strain in π-systems, the relatively strain-free bicyclic system, i.e., bicyclo[2.2.2]octene, was chosen for the structural modification of all the cyclic π-systems, and the successful generation of the cationic species such as radical cation, closed-shell mono- and dications, which are so stable to allow even the X-ray structural analysis, is demonstrated.

• 1 Introduction

• 2 Benzenoid Aromatic Hydrocarbons Fully Annelated with Bicyclo[2.2.2]octene (BCO) Frameworks

• 3 Tropylium Ion with BCO Annelation

• 4 Silatropylium Ion with BCO Annelation

• 5 Cyclooctatetraene (COT) Cations with BCO Annelation

• 6 Sulfur-Containing Cyclic π-Conjugated Systems with BCO Annelation

• 6.1 Thiophene

• 6.2 1,2-Dithiin

• 6.3 1,4-Dithiin

• 6.4 Oligothiophenes with BCO Annelation

• 7 Conclusion

C-C hyperconjugation - cations - one-electron oxidation - X-ray crystallography - aromatic stabilization

References

<A NAME="RA36004ST-1A">1a</A> Balaban AT. Banciu M. Ciorba V. Annulenes, Benzo-, Hetero-, Homo-Derivatives, and their Valence Isomers   CRC Press; Boca Raton: 1987. 

<A NAME="RA36004ST-1B">1b</A> Hopf H. Classics in Hydrocarbon Chemistry   Wiley-VCH; Weinheim: 2000. 

<A NAME="RA36004ST-1C">1c</A> Thematic Issue on Novel Aromatic Compounds; Tetrahedron  2001,  57:  3507-3808  

<A NAME="RA36004ST-1D">1d</A> Thematic Issue on Aromaticity; Chem. Rev.  2001,  101:  1115-1566  

<A NAME="RA36004ST-1E">1e</A> Randic M. Chem. Rev.  2003,  103:  3449 

<A NAME="RA36004ST-1F">1f</A> Balaban AT. Oniciu DC. Katritzky AR. Chem. Rev.  2004,  104:  2777 

<A NAME="RA36004ST-1G">1g</A> Kumaraswamy S. Jalisatgi SS. Matzger AJ. Miljani O. Vollhardt KPC. Angew. Chem. Int. Ed.  2004,  43:  3711 ; and the previous paper cited therein

<A NAME="RA36004ST-2A">2a</A> Handbook of Organic Conductive Molecules and Polymers   Nalwa HS. Wiley-VCH; Chichester: 1997. 

<A NAME="RA36004ST-2B">2b</A> Electronic Materials: The Oligomer Approach   Mullen K. Wegner G. Wiley-VCH; Weinheim: 1998. 

<A NAME="RA36004ST-2C">2c</A> Handbook of Oligo- and Polythiophenes   Fichou D. Wiley-VCH; Weinheim: 1999. 

<A NAME="RA36004ST-2D">2d</A> Tour JM. Acc. Chem. Res.  2000,  33:  791 

<A NAME="RA36004ST-2E">2e</A> Joachim C. Gimzewski JK. Aviram A. Nature  2000,  408:  541 

<A NAME="RA36004ST-2F">2f</A> Nitzan A. Ratner MA. Science  2003,  300:  1384 

<A NAME="RA36004ST-3A">3a</A> Cieplak AS. J. Am. Chem. Soc.  1981,  103:  4540 

<A NAME="RA36004ST-3B">3b</A> Johnson CR. Tait BD. Cieplak AS. J. Am. Chem. Soc.  1987,  109:  5875 

<A NAME="RA36004ST-4A">4a</A> For example of the X-ray structure of 1-adamantyl cation, see: Laube T. Angew. Chem., Int. Ed. Engl.  1986,  25:  349 

<A NAME="RA36004ST-4B">4b</A> For theoretical calculations of 2-methyl-2-butyl (t-pentyl) cation, see: Schleyer PVR. de Carneiro JWM. Koch W. Forsyth DA. J. Am. Chem. Soc.  1991,  113:  3990 

<A NAME="RA36004ST-4C">4c</A> However, in the X-ray crystal structure of the salt of this cation, crystal-packing forces make the C-H hyperconjugation more favorable, see: Kato T. Reed CA. Angew. Chem. Int. Ed.  2004,  43:  2908 

<A NAME="RA36004ST-5A">5a</A> Gerson F. Lopez J. Akaba R. Nelsen SF. J. Am. Chem. Soc.  1981,  103:  6716 

<A NAME="RA36004ST-5B">5b</A> Nelsen S. Teasley MF. Kapp DL. Kessel CR. Grezzo LA. J. Am. Chem. Soc.  1984,  106:  791 

<A NAME="RA36004ST-5C">5c</A> Clark T. Teasley MF. Nelsen SF. Wynberg H. J. Am. Chem. Soc.  1987,  109:  5719 

<A NAME="RA36004ST-6">6</A> Komatsu K. Takeuchi K. Arima M. Waki Y. Shirai S. Okamoto K. Bull. Chem. Soc. Jpn.  1982,  55:  3257 

<A NAME="RA36004ST-7">7</A> Komatsu K. Akamatsu H. Okamoto K. Tetrahedron Lett.  1987,  28:  5889 

<A NAME="RA36004ST-8A">8a</A> Komatsu K. Jinbu Y. Gillette GR. West R. Chem. Lett.  1988,  2029 

<A NAME="RA36004ST-8B">8b</A> Komatsu K. Aonuma S. Jinbu Y. Tsuji R. Hirosawa C. Takeuchi K. J. Org. Chem.  1991,  56:  195 

<A NAME="RA36004ST-9">9</A> Matsuura A. Nishinaga T. Komatsu K. J. Am. Chem. Soc.  2000,  122:  10007 

<A NAME="RA36004ST-10A">10a</A> Frank NL. Baldridge KK. Siegel JS. J. Am. Chem. Soc.  1995,  117:  2102 

<A NAME="RA36004ST-10B">10b</A> Bürgi H.-B. Baldridge KK. Hardcastle K. Frank NL. Gantzel P. Siegel JS. Ziller J. Angew. Chem., Int. Ed. Engl.  1995,  34:  1454 

<A NAME="RA36004ST-10C">10c</A> Matsuura A. Komatsu K. J. Am. Chem. Soc.  2001,  123:  1768 

<A NAME="RA36004ST-11">11</A> Matsuura A. Nishinaga T. Komatsu K. Tetrahedron Lett.  1999,  40:  123 

<A NAME="RA36004ST-12">12</A> Matsuura A. Nishinaga T. Komatsu K. Tetrahedron Lett.  1997,  38:  3427 

<A NAME="RA36004ST-13">13</A> Matsuura A. Nishinaga T. Komatsu K. Tetrahedron Lett.  1997,  38:  4125 

<A NAME="RA36004ST-14">14</A> Nishinaga T. Inoue R. Matsuura A. Komatsu K. Org. Lett.  2002,  4:  1435 

<A NAME="RA36004ST-15">15</A> Nishinaga T. Inoue R. Matsuura A. Komatsu K. Org. Lett.  2002,  4:  4117 

<A NAME="RA36004ST-16">16</A> Kochi JK. Rathore R. Maguéres PL. J. Org. Chem.  2000,  65:  6826 

<A NAME="RA36004ST-17">17</A> The similar structural change in bond length has been observed upon one-electron oxidation of adamantylidene-adamantane and sesquihomoadamantene: Rathore R. Lindeman SV. Zhu C.-J. Schleyer PvR. Kochi JK. J. Org. Chem.  2002,  67:  5106 

<A NAME="RA36004ST-18">18</A>

Nishinaga, T.; Matsuura, A.; Komatsu, K. unpublished.

<A NAME="RA36004ST-19">19</A> Aonuma S. Komatsu K. Takeuchi K. Chem. Lett.  1989,  2107 

<A NAME="RA36004ST-20">20</A> Komatsu K. Akamatsu H. Jinbu Y. Okamoto K. J. Am. Chem. Soc.  1988,  110:  633 

<A NAME="RA36004ST-21A">21a</A> Komatsu K. Takahashi K. Okamoto K. Tetrahedron Lett.  1979,  4747 

<A NAME="RA36004ST-21B">21b</A> Okamoto K. Takeuchi K. Komatsu K. Kubota Y. Ohara R. Arima M. Takahashi K. Waki Y. Shirai S. Tetrahedron  1983,  39:  4011 

<A NAME="RA36004ST-21C">21c</A> Oda M. Kainuma H. Miyatake R. Kuroda S. Tetrahedron Lett.  2002,  43:  3485 

<A NAME="RA36004ST-22">22</A> Komatsu K. Akamatsu H. Aonuma S. Jinbu Y. Maekawa N. Takeuchi K. Tetrahedron  1991,  47:  6951 

<A NAME="RA36004ST-23">23</A> Komatsu K. Nishinaga T. Maekawa N. Kagayama A. Takeuchi K. J. Org. Chem.  1994,  59:  7316 

<A NAME="RA36004ST-24">24</A> Kagayama A. Komatsu K. Nishinaga T. Takeuchi K. Kabuto C. J. Org. Chem.  1994,  59:  4999 

<A NAME="RA36004ST-25A">25a</A> Lambert JB. Zhao Y. Angew. Chem., Int. Ed. Engl.  1997,  36:  400 

<A NAME="RA36004ST-25B">25b</A> Sekiguchi A. Matsuno T. Ichinohe M. J. Am. Chem. Soc.  2000,  122:  11250 

<A NAME="RA36004ST-25C">25c</A> Kim K.-C. Reed CA. Elliott DW. Mueller LJ. Tham F. Lin L. Lambert JB. Science  2002,  297:  825 

<A NAME="RA36004ST-26A">26a</A> Murthy S. Nagano Y. Beauchamp JL. J. Am. Chem. Soc.  1992,  114:  3573 

<A NAME="RA36004ST-26B">26b</A> Nagano Y. Murthy S. Beauchamp JL. J. Am. Chem. Soc.  1993,  115:  10805 

<A NAME="RA36004ST-27">27</A> Jarek RL. Shin SK. J. Am. Chem. Soc.  1997,  119:  6376 

<A NAME="RA36004ST-28">28</A> Nishinaga T. Izukawa Y. Komatsu K. J. Am. Chem. Soc.  2000,  122:  9312 

<A NAME="RA36004ST-29">29</A> Nishinaga T. Izukawa Y. Komatsu K. Tetrahedron  2001,  57:  3645 

<A NAME="RA36004ST-30">30</A> Schleyer PvR. Maerker C. Dransfeld A. Jiao H. Hommes NvE. J. Am. Chem. Soc.  1996,  118:  6317 

<A NAME="RA36004ST-31">31</A> Komatsu K. Nishinaga T. Aonuma S. Hirosawa C. Takeuchi K. Lindner HJ. Richter J. Tetrahedron Lett.  1991,  32:  6767 

<A NAME="RA36004ST-32">32</A> Nishinaga T. Komatsu K. Sugita N. J. Chem. Soc., Chem. Commun.  1994,  2319 

<A NAME="RA36004ST-33">33</A> Dewar MJS. Harget A. Haselbach E. J. Am. Chem. Soc.  1969,  91:  7521 

<A NAME="RA36004ST-34">34</A> Dessau RM. J. Am. Chem. Soc.  1970,  92:  6356 

<A NAME="RA36004ST-35">35</A> Shida T. Iwata S. J. Am. Chem. Soc.  1973,  95:  3473 

<A NAME="RA36004ST-36">36</A> Nishinaga T. Komatsu K. Sugita N. Lindner HJ. Richter J. J. Am. Chem. Soc.  1993,  115:  11642 

<A NAME="RA36004ST-37A">37a</A> Olah GA. Staral JS. Paquette LA. J. Am. Chem. Soc.  1976,  98:  1267 

<A NAME="RA36004ST-37B">37b</A> Olah GA. Staral JS. Liang G. Paquette LA. Melega WP. Carmody MJ. J. Am. Chem. Soc.  1977,  99:  3349 

<A NAME="RA36004ST-38">38</A> Wakamiya A. Nishinaga T. Komatsu K. Chem. Commun.  2002,  1192 

<A NAME="RA36004ST-39">39</A> Nakayama J. Kuroda K. J. Am. Chem. Soc.  1993,  115:  4612 

<A NAME="RA36004ST-40">40</A> Wakamiya A. Nishinaga T. Komatsu K. J. Am. Chem. Soc.  2002,  124:  15038 

<A NAME="RA36004ST-41A">41a</A> Block E. Page J. Toscano JP. Wang C. Zhang X. DeOrazio R. Guo C. Sheridan RS. Towers GHN. J. Am. Chem. Soc.  1996,  118:  4719 

<A NAME="RA36004ST-41B">41b</A> Viola H. Winkler R. In Houben-Weyl, Methoden der Organische Chemie   Vol. E9a:  Schaumann E. Thieme; Stuttgart: 1997.  p.209-249  

<A NAME="RA36004ST-42A">42a</A> Schroth W. Hintzsche E. Spitzner R. Irngartinger H. Siemund V. Tetrahedron Lett.  1994,  35:  1973 

<A NAME="RA36004ST-42B">42b</A> Schroth W. Hintzsche E. Spitzner R. Ströhl D. Sieler J. Tetrahedron  1995,  51:  13247 

<A NAME="RA36004ST-43">43</A> Block E. Birringer M. DeOrazio R. Fabian J. Glass RS. Guo C. He C. Lorance E. Qian Q. Schreder TB. Shan Z. Thiruvazhi M. Wilson GS. Zhang X. J. Am. Chem. Soc.  2000,  122:  5052 

<A NAME="RA36004ST-44">44</A> For example, see: Capasso S. Zagari A. Acta Crystallogr., Sect. B.  1981,  37:  1437 

<A NAME="RA36004ST-45">45</A> Klar G. In Houben-Weyl, Methoden der Organische Chemie   Vol. E9a:  Schaumann E. Thieme; Stuttgart: 1997.  p.250-407  

<A NAME="RA36004ST-46">46</A> Nishinaga T. Wakamiya A. Komatsu K. Chem. Commun.  1999,  777 

<A NAME="RA36004ST-47">47</A> Nishinaga T. Wakamiya A. Komatsu K. Tetrahedron Lett.  1999,  40:  4375 

<A NAME="RA36004ST-48">48</A> Sullivan PD. J. Am. Chem. Soc.  1968,  90:  3618 

For recent reviews, see:

<A NAME="RA36004ST-49A">49a</A> Hotta S. In Handbook of Organic Conductive Molecules and Polymers   Vol. 2:  Nalwa HS. Wiley; Chichester: 1997.  Chap. 8.

<A NAME="RA36004ST-49B">49b</A> Bäuerle P. In Electronic Materials: The Oligomeric Approach   Müllen K. Wegner G. Wiley-VCH; Weinheim: 1998.  Chap. 2.

<A NAME="RA36004ST-49C">49c</A> Handbook of Oligo- and Polythiophenes   Fichou D. Wiley-VCH; Weinheim: 1999. 

<A NAME="RA36004ST-49D">49d</A> Otsubo T. Aso Y. Takimiya K. Bull. Chem. Soc. Jpn.  2001,  74:  1789 

<A NAME="RA36004ST-50A">50a</A> Brédas JL. Street GB. Acc. Chem. Res.  1985,  18:  309 

<A NAME="RA36004ST-50B">50b</A> Heeger AJ. Kivelson S. Schrieffer JR. Su W.-P. Rev. Mod. Phys.  1988,  781:  60 

<A NAME="RA36004ST-51">51</A> Wakamiya A. Yamazaki D. Nishinaga T. Kitagawa T. Komatsu K. J. Org. Chem.  2003,  68:  8305 

<A NAME="RA36004ST-52">52</A> Bäuerle P. Adv. Mater.  1992,  4:  102 

<A NAME="RA36004ST-53">53</A> Nishinaga T. Wakamiya A. Yamazaki D. Komatsu K. J. Am. Chem. Soc.  2004,  126:  3163