Novel rhodium N-heterocyclic carbene catalysed arylation of aldehydes with phenylboronic acid

Reaction of 1,3-dialkylperhydrobenzimidazolinylidene, 1,3-dialkyl-4-methylimidazolinylidene and 1,3-dialkylimidazolinylidene with [RhCl(COD)](2) yields {1,3-dialkylperhydrobenzimidazolin- 2-ylidene}-, {1,3-dialkyl-4-methylimidazolin- 2-ylidene}- {1,3-dialkylimidazolin-2-ylidene} chloro(eta(4)- 1,5- cyclooctadiene) rhodium(I) complexes (2a-c) and ( 4a, b). All compounds synthesised were characterised by elemental analysis, n.m.r. spectroscopy. Phenylboronic acid reacts with aldehydes in the presence of a catalytic amount of the new rhodium(I)-carbene complexes (2a-c) and (4a, b), to give the corresponding aryl secondary alcohols in good yield (73-99%).