Oxazoline-imidazolylidene

Scheme 43 Synthesis of an iridium(I) complex bearing Burgess s chiral oxazoline-imidazolylidene ligand...

Bidentate oxazoline-imidazolylidene ligands, in which both units are linked by a chiral paracyclophane, have been studied in Bolm s group [129]. In this case, the planar chirality of the pseudo-orfho-paracyclophane is combined with the central chirality of an oxazoline (Scheme 48). Compounds 70 were tested in the asymmetric hydrogenation of olefins displaying moderate selectivity (ee s of up to 46% for dimethylitaconate in the presence of 70b). 

The most selective catalyst in this series, complex 32 c, with very bulky substituents at the oxazoline and the imidazolylidene moiety, was used to hydrogenate a range of trisubstituted alkenes with enantiomeric excesses of greater than... 

---