Strained rings are traditionally difficult to functionalize because of unwanted ring-opening reactions that produce more thermodynamically stable forms. A major goal of the Hill group is to develop new functionalization reactions of strained compounds that proceed without delterious ring-opening reacitons. Doing so will enable late-stage functionalizations of strained rings. In this set of projects we study how boron can functionalize C–F and C–H bonds in cyclopropenes through the intermediacy of aromatic ion intermediates.

The development of new reactions is critical for advances in many fields such as agrochemical, pharmaceutical, biological, and material sciences because doing so permits access to unique chemical space. In the Hill lab, we are interested in using dialkylhydrazones to obtain orphaned cyclopropanes. In this set of projects we study how transition metals and ligand combinations impact the stability of cyclopropylcarbinyl intermediates.

Orphaned cyclopropanes are strained three membered rings that arise from the transfer of a non-stabilized carbene. Typically these are dialkylcarbenes, which provide dialkylcyclopropanes. These motifs are commonly found in drugs (e.g. nirmatrelvir) and pyrethroid agrochemicals (see below). A major challenge transfer non-stabilized carbenes to alkenes is the development of bench stable molecules that serve as carbene surrogates. In the Hill lab we have developed new sulfone reagents that transfer non-stabilized carbene groups to weakly activated alkenes.