The reactivity-centered component of the Sorensen Lab is driven by the search for new strategies for the activation of unreactive C–H bonds in an efficient, sustainable manner. As part of our involvement with the NSF Center for Selective C-H Functionalization (NSF-CCHF), we aim to expand the menu of catalytic transformations available to organic chemists through careful design of processes that may or may not have close neighbors in the chemical literature.
Palladium-Catalyzed Cyclizations using Transient Directing Groups (TDGs) – C(sp3)–H functionalization by Pd(II) catalysis offers an expedient route to access polycyclic molecular cores. Our lab aims to develop strategic disconnections to enable creative applications of C–H functionalization logic. To this end, we have adopted a strategy utilizing transient directing groups to direct palladium to traditionally unreactive alkyl C–H bonds and induce subsequent arylative cyclizations.
Relevant References
- Provencher, P. A.‡; Hoskin, J. F.‡; Wong, J. J.; Chen, X.; Yu, J.-Q.; Houk, K. N.; Sorensen, E. J. J. Am. Chem. Soc. 2021, 143, 20035–20041.
- Provencher, P. A.; Bay, K. L.; Hoskin, J. F.; Houk, K. N.; Yu, J.-Q.; Sorensen, E. J. ACS Catal. 2021, 11, 3115–3127.
Transition Metal-Catalyzed Functionalization of Benzaldehydes using TDGS – The wide variety of commercially-available benzaldehydes makes them attractive substrates for complexity-increasing C-H functionalization. Our group has developed a suite of transition-metal catalyzed transformations to introduce various functionality ortho– to aromatic aldehydes via transient directing elements.
Relevant References
- Chen, X.-Y.; Ozturk, S.; Sorensen, E.J. Org. Lett. 2017, 19, 1140–1143.
- Chen, X.-Y.; Ozturk, S.; Sorensen, E.J. Org. Lett. 2017, 19, 6280–6283.
- Chen, X.-Y.; Sorensen, E.J. J. Am. Chem. Soc. 2018, 140, 2789–2792.
- Chen, X.-Y.; Sorensen, E. J. Chem. Sci. 2018, 9, 8951–8956.
Cooperative Hydrogen Atom Transfer (cHAT) – Enzymatic desaturation is thought to occur through sequential hydrogen atom transfer reactions to a single, high-valent metal catalyst which is then regenerated via reoxidation from a stoichiometric electron acceptor. Using this low-temperature desaturation as an inspiration, we have designed a system where each hydrogen atom is accepted by a different catalyst; these two reduced complexes can then be regenerated via a hydrogen evolution step, obviating the need for a stoichiometric oxidant. This stepwise, cooperative hydrogen atom transfer mechanism using base metal catalysts is currently being applied to a variety of dehydrogenative transformations.
Relevant References
- Julian G. West, David Huang & Erik J. Sorensen Nat. Commun. 2015, 6, 10093.
- Abrams, D.J.; West, J.G.; Sorensen, E.J. Chem. Sci. 2016.