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.

This article describes the rational design of 1st generation systems for oxidatively-induced Aryl–CF3 bond-forming reductive elimination from PdII. Treatment of (dtbpy)PdII(Aryl)(CF3) (dtbpy = di-tert-butylbipyridine) with NFTPT (N-fluoro-1,3,5-trimethylpyridium triflate) afforded the isolable PdIV intermediate (dtbpy)PdIV(Aryl)(CF3)(F)(OTf). Thermolysis of this complex at 80 °C resulted in Aryl–CF3 bond-formation. Detailed experimental and computational mechanistic studies have been conducted to gain insights into the key reductive elimination step. Reductive elimination from this PdIV species proceeds via pre-equilibrium dissociation of TfO− followed by Aryl–CF3 coupling. DFT calculations reveal that the transition state for Aryl–CF3 bond formation involves the CF3 acting as an electrophile with the Aryl ligand acting as a nucleophilic coupling partner. These mechanistic considerations along with DFT calculations have facilitated the design of a 2nd generation system utilizing the tmeda (N,N,N’,N’-tetramethylethylenediamine) ligand in place of dtbpy. The tmeda complexes undergo oxidative trifluoromethylation at room temperature.

The past decade has witnessed remarkable growth of catalytic transformations in organic sulfur(VI) fluoride chemistry. This Perspective concentrates exclusively on foundational examples that utilize catalytic strategies to synthesize and react S(VI) fluorides. Key mechanistic studies that aim to provide insight toward future catalytic systems are emphasized.

A method using calcium triflimide [Ca(NTf)] as a Lewis acid to activate sulfonyl fluorides toward nucleophilic addition with amines is described. The reaction converts a wide array of sterically and electronically diverse sulfonyl fluorides and amines into the corresponding sulfonamides in good yield.