No abstract

The usefulness of embedded CF3 substituents within organic substructures necessitates the development of diverse methods for incorporating this functional group. A recently reported route to α-trifluoromethylated alkylboron compounds by an α-transfer mechanism has now been extended to the synthesis of unprecedented, vicinally ditrifluoromethylated alkylboron compounds in a diastereoselective fashion. The utility of these products is highlighted by conversion of the C-B bond into other functional groups.

Novel methods for the incorporation of fluorinated subunits into organic frameworks are important in pharmaceutical, agrochemical, and materials science applications. Herein, the first method for the cross-coupling of benzylic α-trifluoromethylated alkylboron reagents with (hetero)aryl bromides is achieved through application of a photoredox/nickel dual catalytic system. The harsh conditions and high temperatures required by conventional Suzuki-coupling protocols are avoided by exploitation of an odd-electron pathway that permits room temperature transmetalation of these recalcitrant reagents. This method represents the first direct and general route for the synthesis of unsymmetrical 1,1-diaryl-2,2,2-trifluoroethanes, thereby providing efficient access to a previously unexplored chemical space.

The synthesis of potassium trifluoro(N-methylheteroaryl)borates and their use in cross-coupling reactions with various aryl and heteroaryl halides to construct N-methyl heteroaryl-substituted aromatic and heteroaromatic compounds are reported.

In this study we report that fac-[Pt(IV)(dach)(9-EtG)Cl(3)](+) (dach = d,l-1,2-diaminocyclohexane, 9-EtG = 9-ethylguanine) in high pH (pH 12) or phosphate solution (pH 7.4) produces 8-oxo-9-EtG and Pt(II) species. The reaction in H(2)(18)O revealed that the oxygen atom in hydroxide or phosphate ends up at the C8 position of 8-oxo-G. The kinetics of the redox reaction was first order with respect to both Pt(IV)-G and free nucleophiles (OH(-) and phosphate). The oxidation of G initiated by hydroxide was approximately 30∼50 times faster than by phosphate in 100 mM NaCl solutions. The large entropy of activation of OH(-1) (ΔS(‡) = 26.6 ± 4.3 J mol(-1) K(-1)) due to the smaller size of OH(-) is interpreted to be responsible for the faster kinetics compared to phosphate (ΔS(‡) = -195.5 ± 11.1 J mol(-1) K(-1)). The enthalpy of activation for phosphate reaction is more favorable relative to the OH(-) reaction (ΔH(‡) = 35.4 ± 3.5 kJ mol(-1) for phosphate vs. 96.6 ± 11.4 kJ mol(-1) for OH(-1)). The kinetic isotope effect of H8 was determined to be 7.2 ± 0.2. The rate law, kinetic isotope effect, and isotopic labeling are consistent with a mechanism involving proton ionization at the C8 position as the rate determining step followed by two-electron transfer from G to Pt(IV).