N-Fluoro Ammonium Salts of Cinchona Alkaloids in Enantioselective Electrophilic Fluorination

Difluoroenoxysilanes in Catalytic Asymmetric Allylic Alkylation

An allylic substitution with difluoroenoxysilanes as the nucleophile is accomplished for the enantioselective synthesis of α-allylic α,α-difluoroketones. With racemic branched allylic alcohols as the easily accessible allylic electrophile, this branched-selective and enantioconvergent allylic alkylation reaction is catalyzed by an Ir(I)/(P,olefin) complex and overcomes the low nucleophilicity of difluoroenoxysilanes to furnish β-chiral α,α-difluoroketones in moderate to good yields with high enantioselectivity (up to >99.9:0.1 er).

Picking Two out of Three: Defluorinative Annulation of Trifluoromethyl Alkenes for the Synthesis of Monofluorinated Carbo- and Heterocycles

The increasing demand of organofluorine compounds in medicine, agriculture, and materials sciences makes sophisticated methods for their synthesis ever more necessary. Nowadays, not only the C-F bond formation but also the selective C-F bond cleavage of readily available poly- or perfluorine-containing compounds have become powerful tools for the effective synthesis of organofluorine compounds. The defluorinative cross-coupling of trifluoromethyl alkenes with various nucleophiles or radical precursors in an SN 2' manner is a convergent route to access gem-difluoroalkenes, which in turn react with nucleophiles or radical precursors via an SN V-type reaction. If the SN V reactions occur intramolecularly, the dual C-F bond cleavage of trifluoromethyl alkenes allows facile assembly of monofluorinated cyclic skeletons with structural complexity and diversity. In this personal account, we summarized the advances in this field on the basis of coupling and cyclization partners, including binucleophiles, alkynes, diradical precursors and radical precursors bearing a nucleophilic site. Accordingly, the annulation reactions can be achieved by base-mediated sequential SN 2'/SN V reactions, transition metal catalyzed or mediated reactions, photoredox catalysis, and the combination of photocatalytic reactions with SN V reaction. In the context of seminal works of others in this field, a concise summary of the contributions of the authors is also offered.