This work was generously supported by the Deutsche
Forschungsgemeinschaft (Li 556/9-1).
Notes and references
z CCDC 674791 and 674792. For crystallographic data in CIF or
other electronic format see DOI: 10.1039/b719637g
1 (a) R. G. Harvey, Polycyclic Aromatic Hydrocarbons, Wiley, New
York, 1997; (b) M. Bendikov, F. Wudl and D. F. Perepichka,
Chem. Rev., 2004, 104, 4891.
2 J.-M. Aubry, C. Pierlot, J. Rigaudy and R. Schmidt, Acc. Chem.
Res., 2003, 36, 668.
3 (a) N. J. Turro and M.-F. Chow, J. Am. Chem. Soc., 1979, 101,
1300; (b) N. J. Turro, M.-F. Chow and J. Rigaudy, J. Am. Chem.
Soc., 1981, 103, 7218.
4 (a) R. Schmidt, W. Drews and H.-D. Brauer, J. Photochem., 1982,
18, 365; (b) R. Schmidt, K. Schaffner, W. Trost and H.-D. Brauer,
J. Phys. Chem., 1984, 88, 956.
5 (a) W. Fudickar, A. Fery and T. Linker, J. Am. Chem. Soc., 2005,
127, 9386; (b) W. Fudickar and T. Linker, Chem.–Eur. J., 2006, 12,
9276.
Fig. 1 Thermolyses of the endoperoxides 2a–h at 100 1C.
6 G. R. Martinet, J.-L. Ravant, M. H. Medeiros, J. Cadet and P. D.
Mascio, J. Am. Chem. Soc., 2000, 122, 10212.
7 E. L. Clennan, Tetrahedron, 1991, 47, 1343.
8 (a) M. Bobrowski, A. Liwo, S. Oldziej, D. Jeziorek and T.
Ossowski, J. Am. Chem. Soc., 2000, 122, 8112; (b) A. G. Leach
and K. N. Houk, Chem. Commun., 2002, 1243.
9 A. R. Reddy and M. Bendikov, Chem. Commun., 2006, 1179.
10 D. Zehm, W. Fudickar and T. Linker, Angew. Chem., Int. Ed.,
2007, 40, 7689.
11 Experimental details are included in the electronic supplementary
informationw.
12 H.-D. Becker, V. Langer, J. Sieler and H.-C. Becker, J. Org.
for the thermolysis of endoperoxides previously,3 we found
new sterical remote effects on the thermolysis of anthracene
endoperoxides. Thus, the diarylanthracenes 1a–h represent
interesting mechanistic probes, which allow to distinguish
between two different reaction pathways in the oxidation
and cleavage step.
The reaction of 1O2 with the methyl derivative 1f merits
special attention since, compared to the other anthracenes,
subsequent singlet oxygen addition and thermolysis are fast-
est. It is therefore an interesting candidate for a photochromic
system with tolerable fast write and excellent fast erasing
characteristics.5
Chem., 1992, 57, 1883.
13 (a) U. Svanholm and V. D. Parker, J. Am. Chem. Soc., 1976, 98,
2942; (b) M. S. Workentin, V. D. Parker, T. L. Morkin and D. D.
M. Wayner, J. Phys. Chem. A, 1998, 102, 6503; (c) M. Oyama, M.
Yamanuki, T. Sasaki and S. Okazaki, J. Chem. Soc., Perkin Trans.
2, 2000, 1745.
14 (a) F. Wilkinson, W. P. Helman and A. B. Ross, J. Phys. Chem.
Ref. Data, 1995, 24, 663; (b) J.-M. Aubry, B. Mandard-Cazin, M.
Rougee and R. V. Bensasson, J. Am. Chem. Soc., 1995, 117, 9159.
15 (a) J. Erikson, C. S. Foote and T. L. Parker, J. Am. Chem. Soc.,
1977, 99, 6455; (b) R. L. Clough, J. Am. Chem. Soc., 1980, 102,
5242.
16 (a) J. Fossey, D. Lefort and J. Sorba, Free Radicals in Organic
Chemistry, John Wiley & Sons, Chichester, 1995; (b) D. A. Pratt, J.
S. Wright and K. U. Ingold, J. Am. Chem. Soc., 1999, 121, 4877; (c)
H. Zipse, Top. Curr. Chem., 2006, 263, 163.
17 (a) A. Caspar, S. Altenburger-Combrisson and F. Gobert, Org.
Magn. Reson., 1978, 11, 603; (b) P. J. Marriott and Y.-H. Lai, J.
Chromatogr., A, 1988, 447, 29.
In summary, we have shown that the reactivity of 9,10-
diarylanthracenes towards singlet oxygen and the rate of
cycloreversion of the corresponding endoperoxides is strongly
controlled by stereoelectronic remote substituent effects. The
results support zwitterionic intermediates in a stepwise addi-
tion of singlet oxygen and biradical intermediates for the
thermolysis. This change in the pathways of singlet oxygen
reactions was hitherto unknown and should be of interest for
future mechanistic discussions. Finally, the anthracenes are
easily accessible and mark important examples of photochro-
mic materials, whose performance can be tuned by a targeted
choice of the substitution pattern.
ꢀc
This journal is The Royal Society of Chemistry 2008
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