Free radical chemistry have been extensively use in synthetic organic chemistry since their reactivity offers unconventional routes to build chemical complexity. Over the years, the synthetic chemistry community has witnessed the development of many ingenious radical generation strategies which exploited the redox behaviour of the radical precursor or the low bond dissociation energy of one or more bonds within the substrate’s scaffold.
The objective of this doctoral thesis was to use dithiocarbamate and xanthate anions as organocatalysts for the generation of radicals under photochemical conditions. Interestingly, this new class of catalysts could use distinct and complementary mechanisms to activate different substrates towards radical formation. In particular, the high nucleophilicity of our dithiocarbamate catalyst allowed us to generate open-shell intermediates from readily available alkyl (pseudo)halides through an SN2 pathway. The ensuing radicals have been trapped by silyl enol ethers to deliver a wide variety of α-alkylated ketones. In addition, the redox neutral conditions of this process made it tolerant of a cinchona-based amine catalyst, which was used to develop an effective protocol for the asymmetric alkylation of cyclic ketones. On the other hand, the high electron-donicity of dithiocarbamate and xanthogenate donors have been exploited to activate redox active radical precursors through a catalytic electron donor-acceptor (EDA) complex manifold. Excitation with visible light granted access to open-shell intermediates, including non-stabilized carbon radicals and nitrogen-centered radicals. The radicals generated under this regime have been exploited in redox-neutral and net-reductive transformations.
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