Abstract

Photocatalysis is an emerging field that offers sustainable and efficient alternatives to traditional synthetic methods in organic chemistry. This dissertation explores three innovative photochemical strategies for C–C and C–Se cross-coupling and C(sp3)–F bond functionalization. The first chapter presents a novel mono-defluorinative cross-coupling of trifluorotoluenes using multiphoton photoredox catalysis. This method selectively produces difluorobenzyl radicals, enabling the alkylation of styrenes with high chemoselectivity and broad substrate scope. Mechanistic studies, including Stern-Volmer quenching and irradiation experiments, support a quenching pathway involving reduction and protonation. The second chapter focuses on light-induced iron-catalyzed reductive alkylation of imines via ligand-to-metal charge transfer (LMCT) catalysis. Utilizing earth-abundant iron catalysts, this method advances sustainable chemistry by generating chlorine radicals under visible light, facilitating C–H activation and C–C bond formation. Mechanistic insights emphasize the role of iron-catalyzed hydrogen atom transfer (HAT) in the catalytic cycle. The final chapter introduces a metal-free C–Se cross-coupling strategy enabled by photoinduced electron donor-acceptor (EDA) catalysis. This approach, which forms a transient EDA complex under visible light, offers excellent functional group tolerance and operational simplicity, providing a green alternative for constructing C–Se bonds. Detailed mechanistic investigations reveal the photoinduced electron transfer (PET) process central to EDA catalysis. Collectively, these studies contribute to the advancement of photochemical methodologies, offering new tools for the sustainable synthesis of complex organic molecules.