Synthesis of iridium complexes with novel planar chiral chelating imidazolylidene ligands

New planar chiral imidazolium salts such as (S-p)-1-[4-(4 4-dimethyl-4,5-dihydrooxazolyl)[2.2]paracyclophane-12-ylmethyl]-3-methyl imidazolium bromide (S-p)-8a have been synthesized starting from enantiopure 4,12-dibromo[2.2]paracyclophane (S-p)-4. Deprotonation of these salts followed by reaction with [Ir(COD)Cl](2) yielded chelating iridium imidazolylidene complexes 9a-c, which were applied in asymmetric hydrogenations of alkenes. The solid-state structure of (S-p)-9c was determined by single-crystal X-ray structure analysis. (C) 2003 Elsevier Science Ltd. All rights reserved.