Research in our group aims to develop new synthetic reactions that address important problems in organic synthesis. A major theme of these studies is a focus on powerful transformations employing easily accessed substrates and common molecular functionality. This research summary provides an overview of the areas currently under investigation in the group.

Site-selective aliphatic C–H functionalization using tuned heteroatom-centered radicals. Transformations that selectively functionalize aliphatic C−H bonds hold significant promise to streamline complex molecule synthesis. Despite the potential for site-selective C−H functionalization, few intermolecular processes of preparative value exist. We are currently developing reagents and catalysts for a range of practical, predictable, and site-selective aliphatic C–H functionalizations. These transformations proceed in useful chemical yields with substrate as the limiting reagent. The site selectivities of these radical-mediated C−H functionalizations are comparable (or superior) to the most selective intermolecular C−H functionalizations known.

Selected recent publications:

C-H Xanthylation: A Synthetic Platform for Alkane Functionalization
J. Am. Chem. Soc. 2016, 138, 13854–13857

A General Strategy for Aliphatic C-H Functionalization Enabled by Organic Photoredox Catalysis
J. Am. Chem. Soc. 2018, 140, 4213–4217

Reagent-Dictated Site Selectivity in Intermolecular Aliphatic C-H Functionalizations Using Nitrogen-Centered Radicals
Chem. Sci. 2018, 9, 5360–5365

Catalytic C–C bond-forming processes using alkyl electrophiles. Catalyzed cross-couplings are among the premier methods for the formation of C–C bonds in organic synthesis. Traditionally, these transformations have focused on the use of aryl or vinyl halides/sulfonates as electrophiles. We have developed a variety of new catalytic C–C bond-forming reactions involving alkyl electrophiles and fundamental building blocks such as alkenes or carbon monoxide (CO) to streamline the synthesis of a wide range of valuable functionalized small molecules. Our approach capitalizes on novel reactivity in organometallic catalysis to open the door to these unique C–C bond-forming reactions.

Selected recent publications:

Cobalt-Catalyzed Carbonylative Cross-Coupling of Alkyl Tosylates and Dienes: Stereospecific Synthesis of Dienones at Low Pressure
J. Am. Chem. Soc. 2017, 139, 12438-12440

Palladium-Catalyzed Carbocyclizations of Unactivated Alkyl Bromides with Alkenes Involving Auto-tandem Catalysis
J. Am. Chem. Soc. 2071, 139, 11595–11600

Palladium-Catalyzed Alkoxycarbonylation of Unactivated Secondary Alkyl Bromides at Low Pressure
J. Am. Chem. Soc. 2016, 138, 7520-7523

Late-stage C-H functionalization of polymers. Polyolefins that contain polar functionality are important materials for next‐generation lightweight engineering thermoplastics. Post‐polymerization modification is an ideal method for the incorporation of polar groups into branched polyolefins; however, it typically results in chain scission events, which have deleterious effects on polymer properties. In collaboration with the Leibfarth group at UNC, we are developing regioselective C–H functionalizations of a range of polymers that proceed without coincident polymer‐chain scission. Our goal is to achieve a tunable degree of polymer functionalization using new C−H transformations developed in our group.

Selected recent publications:

Regioselective C-H Xanthylation as a Platform for Polyolefin Functionalization
Angew. Chem. Int. Ed. 2018, 57, 6261-6265