The borylation of arenes leads to the formation of synthetically versatile products from unactivated arene reagents. We report that Ir(I) precursors in conjunction with bipyridine ligands catalyze in high yields the borylation of arenes under mild conditions. These reactions encompase arenes bearing both electron-withdrawing and electron-donating substituents. The temperatures required for the transformation are much lower than those previously reported for direct arene borylation. The combination of [Ir(COE)2Cl]2 and (4,4-di-t-butyl)bipyridine even allows for reaction at room temperature. The same catalyst system at 100 degrees C provides remarkably high turnover numbers for a hydrocarbon functionalization process. Mechanistic studies show that the reactions involve uncommon, Ir(II) tris-boryl complexes. An example of this type of complex ligated by di-t-butylbipyridine was isolated and structurally characterized. It reacted rapidly at room temperature to produce aryl boronate esters in high yields.

The first examples of palladium-catalyzed oxidative amination of unactivated alkyl olefins have been identified. To be successful, these reactions must be conducted under cocatalyst-free conditions that involve direct dioxygen-coupled turnover of the palladium catalyst. The oxidative amination products of norbornene and other cyclic alkenes implicate a cis-aminopalladation mechanism.

Bipyridine (bpy) ligands figure prominently in many areas of chemistry. Common precursors to many derivatives are the halomethyl-substituted analogues. This report describes a new, high yield route to these valuable compounds via a trimethylsilyl (TMS) intermediate. 4,4‘-Dimethyl-2,2‘-bpy was reacted with lithium diisopropylamide, and the dianion thus formed was trapped with TMSCl to generate 4,4‘-bis[(trimethylsilyl)methyl]-2,2‘-bpy (1). The TMS group was removed using dry F- sources (TBAF/SiO2 in THF or CsF in DMF) in the presence of BrF2CCF2Br or Cl3CCCl3 to produce the bromide 2 or chloride 3 analogues of 4,4‘-bis(halomethyl)-2,2‘-bipyridine, respectively. The CsF/DMF methodology extends to other electrophiles, including benzaldehyde to give 4,4‘-bis(2-hydroxy-2-phenethyl)-2,2‘-bpy, 6, as well as to alkyl halides. Benzyl Br, dodecyl Br, and α-chloroacetonitrile gave mixtures of di- and monoalkylated products along with the diprotonated product, 4,4‘-dimethyl-2,2‘-bpy.

Dioxygen-coupled oxidative amination of olefins is an attractive, but challenging, catalytic transformation. The present work describes the first general method for intermolecular oxidative amination of aryl olefins with molecular oxygen as the stoichiometric oxidant. This palladium-catalyzed reactivity is compatible with several different nitrogen nucleophiles, including oxazolidinone, phthalimide, pyrrolidinone, and p-toluenesulfonamide. The presence of a catalytic quantity of a Brønsted base in the reaction increases the catalytic activity and switches the reaction regioselectivity.

The synthesis of a series of bis(catecholato)diborane(4) compounds, B2(1,2-O2C6H4)2, B2(1,2-O2C6H3Me-4)2, B2(1,2-O2C6H2Me2-3,5)2, B2[1,2-O2C6H3Bu t -4)]2, and B2[1,2-O2C6H2Bu t 2-3,5]2, is reported. The compounds have been synthesized by reaction of 1% sodium/mercury amalgam with the corresponding halocatecholboranes, which are cleanly formed from the reaction of BCl3 or BBr3 and catechol. Combining these two steps in one pot, B2[1,2-O2C6H3Bu t -4)]2 was prepared from BCl3 and 4-tert-butylcatechol, and B2[1,2-O2C6H2Bu t 2-3,5]2 was prepared from 3,5-di-tert-butylcatechol and BBr3 on a multigram scale. Bis(pinacolato)diborane(4) was not formed from reaction of chloropinacolborane and Na/Hg, but it was formed by in situ addition of pinacol to either B2[1,2-O2C6H3Bu t -4)]2 or B2[1,2-O2C6H2Bu t 2-3,5]2. Cyclic voltammetry indicated that the reduction potentials of the chlorocatecholborane reactant and of the bis(catecholato)diborane(4) product are similar. These similar potentials make selective reduction of haloborane difficult and thus far unique to sodium−mercury amalgam.