Beilstein Journal of Organic Chemistry 2009, 5, No. 25.
References
The photochemistry of the investigated benzopyran 5a may be
summarized as follows: as known from the literature [32], a
very short-lived excited state is observed after photoexcitation
into the S1-band, which decays on a time-scale < 1 ps. The
molecule has reached the open form with some distortion.
Planarization and the resulting built-up of strong absorption in
the visible occurs on the time-scale of several ten picoseconds.
The open form lives only for a limited time: the visible absorp-
tion band centered at 460 nm is found to disappear on the times-
cale of ten microseconds.
1. Feringa, B. L., Ed. Molecular Switches; Wiley-VCH: Weinheim,
Germany, 2001.
2. Crano, J. C.; Flood, T.; Knowles, D.; Kumar, A.; Van Gemert, B.
Pure Appl. Chem. 1996, 68, 1395–1398.
3. Hepworth, J. D.; Heron, B. M. Photochromic naphthopyrans. In
Functional Dyes; Kim, S.-H., Ed.; Elsevier: Amsterdam, Netherlands,
2006; 85 ff.
Chapter 3.
4. Melzig, M.; Weigand, U.; Mann, C. Neutralfarbener photochromer
Kunststoffgegenstand. Ger. Offen. DE 103 07 121 A1, September 2,
2004.
Conclusion
5. Gemert, B. V.; Bergomi, M. P. Photochromic Naphthopyran
Compounds. U.S. Patent 5,066,818, November 19, 1991.
6. Renner, C.; Moroder, L. ChemBioChem 2006, 7, 868–878.
In conclusion, we have synthesized novel photochromic
naphtho- and benzopyrans for applications in the material and
life sciences. A mild and efficient palladium-catalyzed cyana-
tion reaction of bromo-substituted naphtho- and benzopyrans
using Zn(CN)2 has been developed. Also a Sonogashira cross-
coupling furnishing naphthopyran 4 and a palladium-catalyzed
carbonylation yielding ω-amino acid 6 has been carried out.
Detailed studies on nitrile transformations and alternative
carbonylation routes in the presence of other protecting groups
are currently under way in our laboratory. Time-resolved photo-
physical spectroscopy of benzopyran 5a could also demonstrate
a significant influence of the substitution in 3-position on the
reaction dynamics of the ring-opening process.
7. Steinle, W.; Rück-Braun, K. Org. Lett. 2003, 5, 141–144.
8. Cordes, T.; Weinrich, D.; Kempa, S.; Riesselmann, K.; Herre, S.;
Hoppmann, C.; Rück-Braun, K.; Zinth, W.
Chem. Phys. Lett. 2006, 428, 167–173.
9. Willner, I.; Rubin, S.; Wonner, J.; Effenberger, F.; Bäuerle, P.
10.Heinz, B.; Malkmus, S.; Laimgruber, S.; Dietrich, S.; Schulz, C.;
Rück-Braun, K.; Braun, M.; Zinth, W.; Gilch, P.
11.Willner, I.; Rubin, S. Angew. Chem. 1996, 108, 419–439.
Angew. Chem., Int. Ed. Engl. 1996, 35, 367–385.
Supporting Information
12.Woolley, G. A. Acc. Chem. Res. 2005, 38, 486–493.
Full Experimental procedures, characterization data and
copies of spectra for 1–6, 8b and 9–14. Description of the
time-resolved measurements and X-ray analysis of
compounds 1, 3 and 5a.
13.Fujimoto, K.; Amano, M.; Horibe, Y.; Inouye, M.
14.Queiroz, M.-J. R. P.; Abreu, A. S.; Ferreira, P. M. T.; Oliveira, M. M.;
Dubest, R.; Aubard, J.; Samat, A. Org. Lett. 2005, 7, 4811–4814.
Supporting Information File 1
Experimental Part
15.Mao, S.; Benninger, R. K. P.; Yan, Y.; Petchprayoon, C.; Jackson, D.;
Easley, C. J.; Piston, D. W.; Marriott, G.
16.Sakata, T.; Yan, Y.; Marriott, G. J. Org. Chem. 2005, 70, 2009–2013.
17.Lenoble, C.; Becker, R. S. J. Photochem. 1986, 33, 187–197.
Acknowledgments
18.van Gemert, B. Benzo and Naphthopyrans (Chromenes). In Organic
Photochromic and Thermochromic Compounds: Main Photochromic
Families; Crano, J. C.; Guglielmetti, R. J., Eds.; Plenum Press: New
York, NY, USA, 1999; Vol. 1.
This paper is dedicated to Professor Hans-Ulrich Reißig on the
occasion of his 60th birthday. This work was supported by the
Volkswagen Foundation, the Deutsche Forschungsge-
meinschaft (SFB 658, SFB 749, Cluster of Excellence 314 and
Munich-Centre for Advanced Photonics) and the Fonds der
Chemischen Industrie. We thank Prof. Dr. M. Beller, Leibniz-
Institut für Katalyse e. V. an der Universität Rostock (LIKAT),
for the use of his autoclave equipment. Part of this work was
supported by the Alexander von Humboldt-Stiftung through a
research grant to Dr. Saleh A. Ahmed.
Chapter 3.
19.Kodama, Y.; Nakabayashi, T.; Segawa, K.; Hattori, E.; Sakuragi, M.;
Nishi, N.; Sakuragi, H. J. Phys. Chem. A 2000, 104, 11478–11485.
20.Nakabayashi, T.; Nishi, N.; Sakuragi, H. Sci. Prog. 2001, 84, 137–156.
21.Delbaere, S.; Micheau, J.-C.; Vermeersch, G.
22.Delbaere, S.; Micheau, J.-C.; Vermeersch, G.
Page 6 of 7
(page number not for citation purposes)