Reaction Development
We seek to develop new chemical reactivity using organic photoredox catalysis that either 1) addresses longstanding problems in synthesis/catalysis or 2) introduces novel and useful reactivity using simple starting materials. Below are a few highlights from new reaction development that rely on reactive open-shell species generated via organic photoredox catalysis.
Alkene Cation Radicals
Alkene cation radicals accessed via one-electron oxidation of an olefin display unique reactivity. We have harnessed these reactive intermediates for a number of transformations including anti-Markovnikov alkene hydrofunctionalization and difunctionalization as well as polar radical crossover cycloadditions.
Arene Cation Radicals
We have developed a program on arene C-H and C-O bond functionalization via organic photoredox catalysis. Acridinium photocatalysts are capable of one-electron oxidation of a number of (hetero)aromatics with redox potentials <+2.0 V vs. SCE to accomplish a range of C-H bond functionalization reactions including the addition of azoles and ammonia, alkyl amines and cyanide. We have found that anaerobic conditions promote nucleophilic aromatic substitution of alkoxy groups where azoles, alkyl amines and cyanide can displace the alkoxy group.
Alkane C-H Functionalization
Alkane C-H functionalization is possible utilizing organic photoredox catalysis to generate alkyl radical species. We have demonstrated that oxygen-centered radicals, generated upon single electron oxidation of the requisite anions, can act as hydrogen atom abstracting species to accomplish C-H functionalization. Carbamate-protected amines can undergo single electron oxidation and deprotonation adjacent to the nitrogen to allow for alpha-functionalization of carbamate-protected amines and regioselective functionalization of piperizines.