Study of Photoactivatable Processes


Peter Šebej,[ ]Petr Klán

sebej@mail.muni.cz


Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A8, 625 00, Brno, Czech
Republic and Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk
University, Kamenice 126/3, 625 00 Brno, Czech Republic


Photoactivatable processes have been of interest not only for synthetic applications but also for
many promising applications in biologically related areas.[1]

Photoremovable protecting groups (PPG) have been intensively studied in last few decades because
they are an excellent tool for protection and easy deprotection of various functionalities.[2]
o-Nitrobenzyl (oNB),[3] p-hydroxyphenacyl (pHP)[4] and o-methylphenacyl (oMP)[5] chromophores are
among the most widely used PPGs.[6] To determine the scope and limitations of their utilization, we
carried out a series of projects on their mechanistic and synthetic photochemical behavior.

oNB has been shown as a promising and useful PPG for both aliphatic and aromatic diols, as well as
mercaptoalcohols along with a study of the mechanism of its two-step deprotection.[7]

A clean bifurcation between a Type II photochemistry[8] and photo-Favorskii rearrangement[9] has
been discovered in a chromophore combining pHP and oMP functionalities depending on water content
in media.[10] In addition an analogous reactivity of a o-hydroxy-o’-methylphenacyl PPG has been
examined.

                The desyl chromophore[11] is analogous to that of phenacyl, but contains an
asymmetric carbon. We employed this chromophore as a “photoremovable chiral auxiliary” to introduce
a new reagentless method for cleaving-off the chiral auxiliary.[12]
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[1] Dynamic Studies in Biology, Phototriggers, Photoswitches, and Caged Compounds, Goeldner, M.;
Givens, R. S., Eds. Wiley-VCH: Weinheim, 2005.

[2] Klán, P.; Wirz, J., Photochemistry of Organic Compounds: From Concepts to Practice. 1^st ed.;
John Wiley & Sons Ltd.: Chichester, UK, 2009; p 584.

[3] Kloxin, A. M.; Kasko, A. M.; Salinas, C. N.; Anseth, K. S., Science, 2009, 324, 59.

[4] Givens, R. S.; Park, C. H., Tetrahedron Lett. 1996, 37, 6259.

[5] Klán, P.; Zabadal, M.; Heger, D., Org. Lett. 2000, 2, 1569.

[6] Pelliccioli, A. P.; Wirz, J. Photochem. Photobiol. Sci. 2002, 1, 441.

[7] Šebej, P.; Šolomek, T.; Hroudná, Ľ.; Brancová, P.; Klán, P., J. Org. Chem. 2009, 74, 8647.

[8] Pelliccioli, A. P.; Klán, P.; Zabadal, M.; Wirz, J., J. Am. Chem. Soc. 2001, 123, 7931.

[9] Conrad, P. G.; Givens, R. S.; Hellrung, B.; Rajesh, C. S.; Ramseier, M.; Wirz, J., J. Am. Chem.
Soc. 2000, 122, 9346.

[10] Šebej, P.; Lim, B. H.; Park, B. S.; Givens, R. S.; Klán, P., Org. Lett. 2011, 13, in press.

[11] Rajesh, C. S.; Givens, R. S.; Wirz, J., J. Am. Chem. Soc. 2000, 122, 611.

[12] Kammath, V. B.; Šebej, P.; Slanina, T., Kříž, Z.; Klán, P., unpublished results