Abstract: Photoactivatable compounds, also called caged compounds, are those which, upon photoactivation, irreversibly release a species possessing desirable physical, chemical, or biological qualities. Short-wavelength UV radiation is not compatible with many biological and medical applications because it can induce adverse side-reactions. Photorelease induced by red or NIR light is most desired, as the tissue absorption is limited by the absorption of hemoglobin below 600 nm and absorption of water over 900 nm.

Only a few known photoactivatable (caged) molecules can be activated directly by visible/NIR light because the delivered excitation energy is in principle too low for a covalent bond cleavage. In the past 5 years, we have introduced several new chromophores absorbing in the region of 600-1100 nm that can release biologically relevant species,^1-3 for example, H₂S or CO as gaseous signaling molecules. The design, photoreaction mechanisms, spectroscopy and biological applications of these systems will be presented.

References:
[1] Palao E., Slanina T., Muchová L., Šolomek T., Vítek L., Klán P.: J. Am. Chem. Soc. 2016, 138, 126-133.
[2] Slanina T., Shrestha P., Palao E., Kand D., Peterson J., Dutton A., Rubinstein N., Weinstain R., Winter A., Klán P.: J. Am. Chem. Soc. 2017, 139, 15168-15175.
[3] Šolomek T., Wirz J., Klán P.: Acc. Chem. Res. 2015, 48, 3064-3072.

Abstract: Chiral organic molecules are essential to our society so the development of efficient and selective methods to build such molecules is highly important. In this regard, enantioselective catalysis represents a powerful and industrially-relevant tool to access enantioenriched chiral compounds without using stoichiometric chiral reagents. Despite continuous advances in this field, the enantioselective conversion of simple chemicals into relevant chiral molecules remains a formidable challenge. Indeed, contemporary enantioselective methods still routinely require elaborated or pre-activated starting materials as the use of readily available but unactivated substrates often leads to poor reactivity and/or low selectivities. In this lecture, I will present the development of catalytic systems enabling a streamlined access to complex and valuable chiral molecules starting from simple and unactivated substrates.

References:
[1] T. Saget, S. J. Lemouzy, N. Cramer, Angew. Chem. Int. Ed. 2012, 51, 2238.
[2] B. M. Trost, C.-I. Hung, T. Saget, E. Gnanamani, Nat. Catal. 2018, 1, 523.

Abstract: Natural products often embody desirable properties of bioactive molecules and have a long history in basic research and human medicine. Few drugs, however, are themselves natural products and the semisynthetic derivatives predominate. Fully synthetic approaches have the exciting potential to deliver novel analogs inaccessible by semisynthesis (or other means) but are confronted with the intrinsic complexity of natural products. In this lecture, I will describe the chemistry effort ongoing in our laboratory that attempts to respond to these challenges and explore the newly created opportunities.