Phosphorus(V) Lewis acids for element-hydrogen and element-halogen bond activation - Application to reductions and to the synthesis of valuable organic building blocks
Organic Molecular Chemistry - Synthesis and Characterisation
Final Report Abstract
The proposed asymmetric hydrosilylation for carbonyl compounds catalyzed by chiral fluorophosphonium salts could not be achieved. With a variety of conditions, reagents and substrates no marked enantiomeric excesses could be detected. These results, however, triggered a detailed study of substitution effects on Lewis acidity and reactivity in catalysis. This project was carried out in collaboration with Dr. T. vom Stein. The catalysts from the latter project were then used to find a new metal-free, catalytic hydroboration protocol for terminal alkynes with pinacol borane. An in-depth study of catalytically active species and decomposition products led to the development of a simple, more general hydroboration method for both terminal and internal alkynes with readily accessible borane catalysts. This project was carried out in collaboration with Dr. T. vom Stein and M. Fleige. The two other projects that were proposed in the fellowship application, the activation of hydridoborates and element-halogen bonds by fluorophosphonium catalysts, were investigated but proved unsuccessful. Nonetheless, the results obtained from thorough analysis of the reaction outcomes and the decomposition products were used to gauge the limitations of the class of fluorophosphonium Lewis acids. The discussion of these results in weekly meetings with fellow coworkers from the Stephan lab provided useful information to several PhD and MSc projects.
Publications
- Chem. Commun. 2016, 52, 10830-10833
J. Möbus, M. Fleige, T. v. Stein, F. Glorius, D. W. Stephan
(See online at https://doi.org/10.1039/c6cc05360b) - Chem. Commun. 2016, 52, 6387-6390
J. Möbus, T. v. Stein, D. W. Stephan
(See online at https://doi.org/10.1039/c6cc02607a)
