Trimethylammonium-containing rhodacarborane [(9-NMe3-7,8-C2B9H10)RhCl2]2 as a catalyst for the annulation of arylcarboxylic acids with alkynes

Abstract

Rhodacarborane [(9-NMe 3 -7,8-C 2 B 9 H 10 )RhCl 2 ] 2 exhibited moderate catalytic activity in the reaction of annulation of arylcarboxylic acids with alkynes, giving naphthalenes as the major products. Eff ects of the substituent at the carborane ligand, as well as the nature of organic substrates, on the catalytic activity and selectivity of the reaction were estimated. In particular, it was revealed that a replacement of the NMe 3 group at the carborane ligand with the SMe 2 one leads to a signifi cantly decreased activity of the catalyst.

Triphenylcyclopentadienyl Rhodium Complexes in Catalytic C–H Annulations. Application for Synthesis of Natural Isocoumarins

“…For example, naphthalene 8ca was isolated as a mixture of regioisomers with the 6-isomer predominating. Anthracene 8ga was isolated as the only product; isomeric phenanthrene was not detected. , We were also able to involve benzo­[ b ]­thiophene-2-carboxylic and terephthalic acids in annulation with diphenylacetylene to give the corresponding isocoumarins and naphthalenes in low to moderate yields. Thus, when iodide 1b is used under mild conditions, isocoumarin 7ha is formed in a higher yield than when using the classical [Cp*RhCl 2 ] 2 catalyst in our hands (37 vs 28%).…”

Interligand Interactions in Half-Sandwich Nickelacarboranes with Phosphine Ligands: Away from Skeletal Rearrangements

“…Despite its more than 50 year history, the chemistry of nickelacarboranes has received much less development compared to the chemistry of cobalta- and ferracarboranes, which are characterized by the formation of extremely stable bis­(dicarbollide) complexes, − as well as the chemistry of rhoda- and ruthenacarboranes, , which are widely studied as catalysts for various processes. − This is largely due to the increased tendency of nickelacarboranes to skeletal rearrangements, − as well as the often uninformative 11 B NMR spectra of nickelacarboranes, which makes their identification problematic. Certain problems are also associated with the lack of methods for modifying nickel bis­(dicarbollide) and its reduced stability , compared to iron and cobalt bis­(dicarbollides).…”