Free Standard AU & NZ Shipping For All Book Orders Over $80!
Register      Login
Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
Shopping Cart: ( empty )
You are here: Home > Journals > CH > CH10297
RESEARCH FRONT
Contents Vol 63(12)

Demethylation of an Allene Bearing Two Dimethoxythioxanthene Groups by Oxidation via a Vinyl Cation Intermediate

Torahiko Yamaguchi A , Shin-ichi Fuku-en A , Shun Sugawara A , Satoshi Kojima A and Yohsuke Yamamoto A B
+ Author Affiliations
- Author Affiliations

A Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.

B Corresponding author. Email: yyama@sci.hiroshima-u.ac.jp

Australian Journal of Chemistry 63(12) 1638-1644 https://doi.org/10.1071/CH10297
Submitted: 10 August 2010  Accepted: 31 October 2010   Published: 6 December 2010

Abstract

With the objective of preparing an isolable triplet carbene, we have carried out the oxidation of an allenic compound bearing two thioxanthene moieties (5). Relatively weak oxidants such as Ph3C+BF4 – gave 8, which is the conjugate acid of 5, as a result of a one-electron oxidation followed by hydrogen abstraction, whereas relatively strong oxidants such as SbCl5 furnished a dicationic ketal (9) as a consequence of oxidation and demethylation. Computations on the supposed dicationic intermediate suggest that the singlet state is more stable than the triplet state by 6.7 kcal mol–1 and that the reason for this peculiarity is because the singlet state is essentially a vinyl cation stabilized by a coordinating methoxy group.


References

[1]  For leading reviews, see: Sander W. , Bucher G. , Wierlacher S. , Chem. Rev. 1993, 93, 1583. 10.1021/CR00020A009
      G. Bertrand, Carbene Chemistry: From Fleeting Intermediates to Powerful Reagents 2002 (Marcel Dekker: New York, NY).

[2]  For recent leading reviews on singlet carbenes, see: Bourissou D. , Guerret O. , Gabbaï F. P. , Bertrand G. , Chem. Rev. 2000, 100, 39. 10.1021/CR940472U
      G. Bertrand, in Reactive Intermediate Chemistry 2004, Ch. 8, pp. 329–373 (Eds R. A. Moss, M. S. Platz, M. Jones, Jr.) (Wiley-VCH: Hoboken, NJ).
      (c) Y. Canac, M. Soleilhavoup, S. Conejero, G. Bertrand, J. Organomet. Chem. 2004, 689, 3857.
         | Crossref | GoogleScholarGoogle Scholar |
      (d) P. de Frémont, N. Marion, S. P. Nolan, Coord. Chem. Rev. 2009, 253, 862.
         | Crossref | GoogleScholarGoogle Scholar |
      (e) J. Vignolle, X. Cattoën, D. Bourissou, Chem. Rev. 2009, 109, 3333.
         | Crossref | GoogleScholarGoogle Scholar |

[3]  For recent comprehensive reviews on the use of carbenes as ligands, see: Herrmann W. A. , Angew. Chem. Int. Ed. 2002, 41, 1290. 10.1002/1521-3773(20020415)41:8<1290::AID-ANIE1290>3.0.CO;2-Y
      (b) C. M. Crudden, D. P. Allen, Coord. Chem. Rev. 2004, 248, 2247.
         | Crossref | GoogleScholarGoogle Scholar |
      (c) N. M. Scott, S. P. Nolan, Eur. J. Inorg. Chem. 2005, 1815.
         | Crossref | GoogleScholarGoogle Scholar |
      S. P. Nolan, N-Heterocyclic Carbenes in Synthesis 2006 (Wiley-VCH: Weinheim).
      (e) H. Clavier, S. P. Nolan, Annu. Rep. Prog. Chem. Sect. B 2007, 103, 193.
         | Crossref | GoogleScholarGoogle Scholar |
      F. Glorius, N-Heterocyclic Carbenes in Transition Metal Catalysis 2007 (Springer-Verlag: Berlin-Heidelberg).
      (g) F. E. Hahn, M. C. Jahnke, Angew. Chem. Int. Ed. 2008, 47, 3122.
         | Crossref | GoogleScholarGoogle Scholar |
      (h) R. Corberán, E. Mas-Marzá, E. Peris, Eur. J. Inorg. Chem. 2009, 1700.
         | Crossref | GoogleScholarGoogle Scholar |
      (i) S. Díez-González, N. Marion, S. P. Nolan, Chem. Rev. 2009, 109, 3612.
         | Crossref | GoogleScholarGoogle Scholar |
      (j) X. Bantreil, J. Broggi, S. P. Nolan, Annu. Rep. Prog. Chem. Sect. B 2009, 105, 232.
         | Crossref | GoogleScholarGoogle Scholar |
      O. Kuhl, Functionalised N-Heterocyclic Carbene Complexes 2010 (Wiley: Chichester).

[4]  For leading reviews on the use of carbenes as organocatalysts, see: Marion N. , Díez-González S. , Nolan S. P. , Angew. Chem. Int. Ed. 2007, 46, 2988. 10.1002/ANIE.200603380
      (b) D. Enders, O. Niemeier, A. Henseler, Chem. Rev. 2007, 107, 5606.
         | Crossref | GoogleScholarGoogle Scholar |
      (c) E. M. Phillips, A. Chan, K. A. Scheidt, Aldrichim Acta 2009, 42, 55.

[5]  For leading reviews on other applications of carbenes, see: Hindi K. M. , Panzner M. J. , Tessier C. A. , Cannon C. L. , Youngs W. J. , Chem. Rev. 2009, 109, 3859. 10.1021/CR800500U
      (b) M.-L. Teyssot, A.-S. Jarrousse, M. Manin, A. Chevry, S. Roche, F. Norre, C. Beaudoin, L. Morel, D. Boyer, R. Mahiou, A. Gauti, Dalton Trans. 2009, 6894.
         | Crossref | GoogleScholarGoogle Scholar |
      (c) L. Mercs, M. Albrecht, Chem. Soc. Rev. 2010, 39, 1903.
         | Crossref | GoogleScholarGoogle Scholar |

[6]  For leading reviews on triplet carbenes, see: Tomioka H. , Acc. Chem. Res. 1997, 30, 315. 10.1021/AR9602157
      H. Tomioka, in Reactive Intermediate Chemistry 2004, Ch. 9, pp. 375–461 (Eds R. A. Moss, M. S. Platz, M. Jones, Jr.) (Wiley-VCH: New Jersey, NJ).
      (c) T. Itoh, K. Hirai, H. Tomioka, Bull. Chem. Soc. Jpn. 2007, 80, 138.
         | Crossref | GoogleScholarGoogle Scholar |
      (d) K. Hirai, T. Itoh, H. Tomioka, Chem. Rev. 2009, 109, 3275.
         | Crossref | GoogleScholarGoogle Scholar |

[7]  For factors to stabilize triplet carbenes, see: Woodcock H. L. , Moran D. , Brooks B. R. , Schleyer P. R. , Schaefer H. F. III , J. Am. Chem. Soc. 2007, 129, 3763. 10.1021/JA068899T
      (b) A. Nemirowski, P. R. Schreiner, J. Org. Chem. 2007, 72, 9533.
         | Crossref | GoogleScholarGoogle Scholar |

[8]  (a) K. Hirai, H. Tomioka, J. Am. Chem. Soc. 1999, 121, 10213.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK1MXmt12nsbs%3D&md5=dc224e29edcf2b9542ffd1367f2d2efcCAS |
      (b) T. Itoh, Y. Nakata, K. Hirai, H. Tomioka, J. Am. Chem. Soc. 2006, 128, 957.
         | Crossref | GoogleScholarGoogle Scholar |

[9]  E. Iwamoto, K. Hirai, H. Tomioka, J. Am. Chem. Soc. 2003, 125, 14664.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXovVSitL8%3D&md5=dfba0c3b3bfff531dc8aba7ddd997296CAS | 14640615PubMed |

[10]  M. Kawano, K. Hirai, H. Tomioka, Y. Ohashi, J. Am. Chem. Soc. 2007, 129, 2383.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXht1Wqsb8%3D&md5=28635b5983bd8da52072dcedc86bcf64CAS | 17263535PubMed |

[11]  (a) T. Yamaguchi, Y. Yamamoto, Y. Fujiwara, Y. Tanimoto, Org. Lett. 2005, 7, 2739.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXksVeqsr0%3D&md5=1c5c85bc55c261009160812e4cd77f33CAS | 15957935PubMed |
      (b) T. Yamaguchi, Y. Yamamoto, Chem. Lett. 2007, 36, 1438.
         | Crossref | GoogleScholarGoogle Scholar |
      (c) T. Yamaguchi, Y. Yamamoto, D. Kinoshita, K.-y. Akiba, Y. Zhang, C. A. Reed, D. Hashizume, F. Iwasaki, J. Am. Chem. Soc. 2008, 130, 6894.
         | Crossref | GoogleScholarGoogle Scholar |
      (d) T. Yano, T. Yamaguchi, Y. Yamamoto, Chem. Lett. 2009, 38, 794.
         | Crossref | GoogleScholarGoogle Scholar |

[12]  N. G. Connelly, W. E. Geiger, Chem. Rev. 1996, 96, 877.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28XhsVGhu7Y%3D&md5=763d399f8085d7f06fc11273de026d17CAS | 11848774PubMed |

[13]  Compound 5 could not be protonated by the weakly acidic H2O. However, compound 8 could be deprotonated by pyridine to reproduce 5.

[14]  We have previously carried out DFT calculations at B3PW91/6–31G(d) level to estimate weak interactions and have found that experimental results are reproduced to a high degree with this method. (cf. M. Yamashita, Y. Yamamoto, K.-Y. Akiba, D. Hashizume, F. Iwasaki, N. Takagi, S. Nagase, J. Am. Chem. Soc. 2005, 127, 4354.) 10.1021/JA0438011

[15]  A. H. Winter, D. E. Falvey, J. Am. Chem. Soc. 2010, 132, 215.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhsFWmur3M&md5=9aa082ac0264dd8de0e0d10989e27af0CAS | 19961230PubMed |

[16]  H. Chaumeil, S. Signorella, C. L. Drian, Tetrahedron 2000, 56, 9655.
         | Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXotlamsr0%3D&md5=2f67b80d9433d44dd2e68b766e7ae5f0CAS |

[17]  M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, V. G. Zakrzewski, J. A. Montgomery, R. E. Stratmann, Jr, J. C. Burant, S. Dapprich, J. M. Millam, A. D. Daniel, S. K. N. Kudin, M. C. Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi, B. Mennucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski, G. A. Petersson, P. Y. Ayala, Q. Cui, K. Morokuma, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. Cioslowski, J. V. Ortiz, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. Gomperts, L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, C. Gonzalez, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M. W. Wong, J. L. Andres, C. Gonzalez, M. Head-Gordon, E. S. Replogle, J. A. Pople, Gaussian 98 (Revision A.5) 1998 (Gaussian, Inc.: Pittsburgh, PA)