Mechanism of the Norrish–Yang Photocyclization Reaction of an Alanine Derivative in the Singlet State: Origin of the Chiral-Memory Effect†
Adalgisa Sinicropi Dr.
Dipartimento di Chimica, Università degli Studi di Siena via Aldo Moro, 53100 Siena, Italy, Fax: (+39) 0577-234-278
Search for more papers by this authorFrédérique Barbosa Dr.
Department of Chemistry, St. Johanns-Ring 19, 4056 Basel, Switzerland, Fax: (+41) 61-267-1105
Current address: Cerep, 128 rue Danton, 92500 Rueil Malmaison, France
Search for more papers by this authorRiccardo Basosi Prof. Dr.
Dipartimento di Chimica, Università degli Studi di Siena via Aldo Moro, 53100 Siena, Italy, Fax: (+39) 0577-234-278
Search for more papers by this authorBernd Giese Prof. Dr.
Department of Chemistry, St. Johanns-Ring 19, 4056 Basel, Switzerland, Fax: (+41) 61-267-1105
Search for more papers by this authorMassimo Olivucci Prof. Dr.
Dipartimento di Chimica, Università degli Studi di Siena via Aldo Moro, 53100 Siena, Italy, Fax: (+39) 0577-234-278
Search for more papers by this authorAdalgisa Sinicropi Dr.
Dipartimento di Chimica, Università degli Studi di Siena via Aldo Moro, 53100 Siena, Italy, Fax: (+39) 0577-234-278
Search for more papers by this authorFrédérique Barbosa Dr.
Department of Chemistry, St. Johanns-Ring 19, 4056 Basel, Switzerland, Fax: (+41) 61-267-1105
Current address: Cerep, 128 rue Danton, 92500 Rueil Malmaison, France
Search for more papers by this authorRiccardo Basosi Prof. Dr.
Dipartimento di Chimica, Università degli Studi di Siena via Aldo Moro, 53100 Siena, Italy, Fax: (+39) 0577-234-278
Search for more papers by this authorBernd Giese Prof. Dr.
Department of Chemistry, St. Johanns-Ring 19, 4056 Basel, Switzerland, Fax: (+41) 61-267-1105
Search for more papers by this authorMassimo Olivucci Prof. Dr.
Dipartimento di Chimica, Università degli Studi di Siena via Aldo Moro, 53100 Siena, Italy, Fax: (+39) 0577-234-278
Search for more papers by this authorThis work was supported by the HFSP (RG 0229/2000M), the Università di Siena (Progetto di Ateneo A.A. 00/04), FIRB project no. RBAU01EPMR, and the Swiss National Science Foundation.
Graphical Abstract
Remember how it was …︁? A mechanistic explanation for the chiral-memory effect in Norrish–Yang photoreactions has been obtained by computing the reaction pathway (see figure) at the ab initio level. The results show that both the ultrafast excited-state decay, which occurs at a conical intersection (CI), and the specific hydrogen-bonded structure of the primary diradical intermediate determine the high stereoselectivity of the reaction.
Supporting Information
Supporting information for this article (coordinates and energies of all optimized structures) is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z461898_s.pdf or from the author.
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References
- 1A. Córdova, W. Notz, G. Zhong, J. M. Betancort, C. F. Barbas III, J. Am. Chem. Soc. 2002, 124, 1842.
- 2P. Wessig, P. Wettstein, B. Giese, M. Neuburger, M. Zehnder, Helv. Chim. Acta 1994, 77, 829.
- 3W. Weigel, S. Schiller, G. Reck, H.-G. Henning, Tetrahedron Lett. 1993, 34, 6737.
- 4C. Wyss, R. Batra, C. Lehmann, S. Sauer, B. Giese, Angew. Chem. 1996, 108, 2660;
10.1002/ange.19961082118 Google ScholarAngew. Chem. Int. Ed. Engl. 1996, 35, 2529.
- 5K. Nagasawa, A. Georgieva, T. Nakata, Tetrahedron 2000, 56, 187.
- 6R. Kawecki, Tetrahedron 2001, 57, 8385.
- 7C. Grison, S. Genève, E. Halbin, P. Coutrot, Tetrahedron 2001, 57, 4903.
- 8F. Benedetti, M. Magnan, S. Miertus, S. Norbedo, D. Parat, A. Tossi, Bioorg. Med. Chem. Lett. 1999, 9, 3027.
- 9D. Voet, J. G. Voet, Biochemie, VCH, Weinheim, 1992.
- 10B. Giese, P. Wettstein, C. Stähelin, F. Barbosa, M. Neuburger, M. Zehnder, P. Wessig, Angew. Chem. 1999, 111, 2722;
10.1002/(SICI)1521-3757(19990903)111:17<2722::AID-ANGE2722>3.0.CO;2-K Google ScholarAngew. Chem. Int. Ed. 1999, 38, 2586.10.1002/(SICI)1521-3773(19990903)38:17<2586::AID-ANIE2586>3.0.CO;2-K CAS PubMed Web of Science® Google Scholar
- 11A. G. Griesbeck, Synlett 2003, 4, 451.
- 12P. Celani, M. A. Robb, M. Garavelli, F. Bernardi, M. Olivucci, Chem. Phys. Lett. 1995, 243, 1.
- 13K. Andersson, M. R. A. Blomberg, M. P. Fülscher, G. Karlstöm, R. Lundh, P.-A. Malmqvist, P. Neogrády, J. Olsen, B. O. Roos, A. J. Sadlej, M. Schütz, L. Seijo, L. Serrano-Andrés, P. E. M. Siegbahn, P.-O. Widmark, MOLCAS, Version 4, University of Lund, Lund, Sweden, 1997.
- 14Gaussian 98 (Revision A.7), 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, J. C. Burant, S. Dapprich, J. M. Millam, A. D. Daniels, 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, R. 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. G. Johnson, W. Chen, M. W. Wong, J. L. Andres, M. Head-Gordon, E. S. Replogle, J. A. Pople, Gaussian, Inc., Pittsburgh, PA, 1998.
- 15“Ab initio Methods in Quantum Chemistry-II”: B. O. Roos, Adv. Chem. Phys. 1987, 69, 399.
- 16B. O. Roos, Acc. Chem. Res. 1999, 32, 137.
- 17Geometry optimization and reaction-path computations were carried out at the CASSCF level of theory with a complete active space including ten electrons in eight orbitals, and the 6-31G* basis set available in Gaussian 98.[13] The orbitals comprise the two σ and σ* C8H9 orbitals, the four π and π* orbitals of the C1O2 and C11012 bonds, and the N6 and O2 lone-pair orbitals. Because of wavefunction instability, the S0 transition state TS-back-H was optimized by using state-average CASSCF with a S0 and S1 weight of 0.5. The relaxation coordinates were computed according to the following procedure: 1) The CI between the excited state (S1) and the ground state (S0) was optimized by using the methodology available in Gaussian 98; 2) the S0 relaxation pathways were computed starting from the optimized CI point by the IRD method, as described in reference [11], and the IRC method available in Gaussian 98. To obtain more-accurate reaction energetics we reevaluated the energy along selected points of the relaxation coordinate at the CASPT2 level by using the program package MOLCAS-4.[12]
- 18H. Ihmels, J. R. Scheffer, Tetrahedron 1999, 55, 885.
- 19M. Leibovitch, G. Olovsson, J. R. Scheffer, J. Trotter, J. Am. Chem. Soc. 1998, 120, 12 755.
- 20F. Bernardi, M. Olivucci, M. A. Robb, Chem. Soc. Rev. 1996, 25, 321.
- 21A. Migani, M. Olivucci in Conical Intersections: Electronic Structure, Dynamics and Spectroscopy (Eds.: ), World Scientific, Singapore, 2004.
- 22If the thermal equilibration of TD, kinetic control, and a parallel reaction scheme are assumed, a simple Arrhenius treatment leads to a ratio 2/3 of exp(E3−E2)/RT, in which E3 is the barrier to the production of 3 and E2 is the barrier to the production of 2. According to this equation, a ratio of 85:15 requires an E3−E2 value of approximately 1 kcal mol−1. Thus, if the errors in our computational model are taken into account, the computed value of 0.7 kcal mol−1 is consistent with the expected value and with the observed dominance of isomer 2. Note also that the error associated with the computation of the energy barriers is expected to be close to the value of E3−E2.
