NOVEL METALLAPHOTOREDOX PLATFORMS FOR THE CONSTRUCTION OF SATURATED SCAFFOLDS

Abstract

Over the past decade, photoredox catalysis brought up a renaissance of organic synthesis based on the reactivity of free radicals. Harnessing visible light with photoactive compounds enabled the mild conversion of readily available building blocks into versatile open-shell intermediates. Furthermore, merging these catalysis modes with transition metal catalysis radically expanded the scope of the fragment-coupling logic onto terrains challenging for conventional thermal chemistry, such as cross-coupling of aliphatic systems. This dissertation describes research efforts toward applying photoredox catalysis in developing methods that enable the construction of saturated scaffolds. Chapter 2 describes a dual photo/nickel catalytic manifold that performs cross-coupling via an unconventional sequence involving free radical generation, radical sorting via selective binding to a Ni(II) center, and bimolecular homolytic substitution (SH2) at a high-valent nickel–alkyl complex. This catalytic manifold enables the hitherto elusive cross-coupling of diverse aliphatic carboxylic acids to generate valuable C(sp³)–C(sp³)-products. Chapter 3 describes a copper metallaphotoredox manifold for an open shell deoxygenative coupling of alcohols with N-nucleophiles forging C(sp³)–N bonds, a linkage highly sought in pharmaceutical agents but challenging to access via conventional cross-coupling techniques.