A system consisting of catalytic amounts of [(p-cym)RuCl ] /PEt ⋅HBF , K CO as the base, and NMP as the solvent efficiently mediates the ortho-C-H arylation of benzoic acids with aryl bromides at 100 °C. Replacing the phosphine ligand with the amino acid dl-pipecolinic acid enables the analogous transformation with aryl chlorides. The key advantage of this broadly applicable transformation is the use of an inexpensive ruthenium catalyst in combination with simple carboxylates as directing groups, which can either be tracelessly removed or used as anchor points for decarboxylative ipso substitutions.

As ystem consisting of catalytic amounts of [(p-cym)RuCl 2 ] 2 /PEt 3 ·HBF 4 ,K 2 CO 3 as the base,a nd NMP as the solvent efficiently mediates the ortho-CÀHa rylation of benzoic acids with aryl bromides at 100 8 8C. Replacing the phosphine ligand with the amino acid dl-pipecolinic acid enables the analogous transformation with aryl chlorides.The key advantage of this broadly applicable transformation is the use of an inexpensive ruthenium catalyst in combination with simple carboxylates as directing groups,w hich can either be tracelessly removed or used as anchor points for decarboxylative ipso substitutions.

In the presence of a[Cp*RhCl 2 ] 2 catalyst, the Lewis acid In(OTf) 3 ,a nd the mild base Na 2 CO 3 ,a romatic carboxylates and a,b-unsaturated ketones undergo au nique hydroarylation/Claisen/retro-Claisen process to give the corresponding indanones.I nt his carboxylate-directed ortho-CÀHa nnelation, the C À COR bond of the ketone and the CO À OH group of the aromatic carboxylate are cleaved, and the hydroxy group is transferred from the aromatic to the aliphatic acyl residue. This reactivity is synthetically useful, particularly when starting from cyclic ketones,w hich are converted into indanones bearing aliphatic carboxylate side chains,thus greatly increasing the molecular complexity of aromatic carboxylates in asingle step.Scheme 3. Preferential formation of diketones at incomplete conversion. Scheme 4. Mechanistic investigations. Angewandte Chemie Communications

Trihalide salts were found to efficiently promote photochemical dediazotizing halogenations of diazonium salts. In contrast to classical Sandmeyer reactions, no metal catalysts are required to achieve high yields and outstanding selectivities for halogenation over competing hydridodediazotization. Convenient protocols are disclosed for synthetically meaningful brominations, iodinations, and chlorinations of diversely functionalized derivatives.

In the presence of [p-cymene)­RuCl2]2, (E)-configured alkenyl bromides couple with aromatic carboxylates to form ortho-vinylbenzoic acids. This C–H vinylation proceeds in high yields without any activating phosphine ligands and has an excellent functional group tolerance. Starting from commonly available (E/Z )-mixtures of alkenyl bromides, (E)-configured vinyl arenes or dienes are formed exclusively. Mechanistic studies show that this selectivity is achieved because the (E)-configured alkenyl bromides undergo a smooth coupling, whereas the (Z)-isomers are rapidly eliminated with the formation of alkynes.