Pr Thorsten Bach

Technische Universität München

Chirality and Light: Enantioselective Catalysis of Photochemical Reactions

[2+2] Photocycloaddition reactions belong undisputedly to the most important reaction classes in photochemistry. The creation of up to four new stereogenic centers in a single step and the further use of the formed cyclobutane rings – either directly or after appropriate ring opening – are hallmarks of this powerful transformation. In our group, we have studied two different approaches to achieve a catalytic enantioselective reaction course in [2+2] photocycloaddition reactions. The first approach is based on a triplet energy transfer by hydrogen-bonding chiral catalysts, which in turn are derived from a previously described template (1,2). The second approach relies on the use of Brønsted or Lewis acids, which change the photophysical properties of the chromophore and ideally allow for a selective excitation in the chiral environment which they provide (3,4). Beyond [2+2] photocycloaddition chemistry our studies are directed towards photochemical rearrangement and isomerization reactions with a potential for synthetic applications. The presentation discusses the background of the above-mentioned experiments and provides the latest results of our research efforts in this area.

(1)   C. Müller, M. M. Maturi, A. Bauer, M. C. Cuquerella, M. A. Miranda, T. Bach, J. Am. Chem. Soc. 2011, 133, 16689-16697.

(2)   A. Tröster, R. Alonso, A. Bauer, T. Bach, J. Am. Chem. Soc. 2016, 138, 7808-7811.

(3)   R. Brimioulle, T. Bach, Science 2013, 342, 840-843.

(4)   C. Brenninger, A. Pöthig, T. Bach, Angew. Chem. Int. Ed. 2017, 56, 4337-4341.