This communication describes the rational design and synthesis of a remarkably stable Pd IV monoaryl fluoride complex (t-Bu-bpy)Pd IV (p-FC 6 H 4 )(F) 2 (FHF) (t-Bu-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine). This and related complexes undergo Ar-F bond formation in the presence of "F + " sources. This work serves as a foundation for the development of a Pd II/IV catalyzed coupling reactions to form aryl fluorides.Aryl fluorides are important components of many biologically active molecules, including pharmaceuticals, agrochemicals, and PET imaging agents. 1,2 While a variety of synthetic approaches are available for generating sp 3 C-F bonds, 2 there are relatively few general and practical methods for the formation of aryl fluorides. 2-4 To date, the most common routes to these molecules involve fluorination of aryl diazonium salts (the Balz-Schiemann reaction) 3a and other nucleophilic aromatic substitution reactions with F − . 3b,4 However, these transformations have significant limitations (e.g., modest scope, the requirement for potentially

This communication describes oxidatively-induced Ar-CF 3 bond-forming reductive elimination from new Pd II complexes of general structure (L~L)Pd II (Ar)(CF 3 ). The electrophilic fluorinating reagent N-fluoro-2,4,6-trimethylpyridinium triflate promotes these reactions in good to excellent yields. The palladium(IV) intermediate ( t

The reaction of [(bzq)Pd(OAc)]2 (bzq = benzo[h]quinoline) with “CF3+” reagents to afford the monomeric PdIV aquo complex (bzq)Pd(CF3)(OAc)2(OH2) is demonstrated. Heating this PdIV adduct at 60 °C for 12 h leads to highly chemoselective Aryl–CF3 bond-forming reductive elimination. The rate and yield of this transformation are both significantly enhanced by the addition of Brønsted and Lewis acidic additives. The mechanism of C–CF3 bond-formation from (bzq)Pd(CF3)(OAc)2(OH2) has been studied, and the major pathway is proposed to involve pre-equilibrium acetate dissociation followed by C–CF3 coupling. Finally, this monomeric PdIV complex is shown to be a kinetically competent intermediate for C–H trifluoromethylation with “CF3+” reagents. Collectively, these studies provide valuable insights about the speciation, nuclearity, and reactivity of Pd intermediates in catalytic C–H trifluoromethylation reactions.

A one-pot Pd-catalyzed conversion of aryl iodide to aryl sulfonyl fluorides using DABSO and Selectfluor has been developed generating aryl sulfonyl fluorides in good to excellent yields. The reaction results in the generation of electronically and sterically diverse sulfonyl fluorides. Additionally, sulfonyl fluorides can be converted to aryl sulfonamides and sulfonic esters using CsCO under mild conditions.

This communication describes the first observation and study of C–H activation at a PdIV center. This transformation was achieved by designing model complexes in which the rate of reductive elimination is slowed relative to that of the desired C–H activation process. Remarkably, the C–H activation reaction can proceed under mild conditions and with complementary site selectivity to analogous transformations at PdII. These results provide a platform for incorporating this new reaction as a step in catalytic processes.