SYNTHESIS OF CHIRAL HALF-SANDWICH RHODIUM OXAZOLINE COMPLEXES AND THEIR USE AS ASYMMETRIC DIELS-ALDER CATALYSTS

The reaction of [(eta-C5Me5)RhCl2](2) with bidentate oxazoline contain ing ligands provides the cations [(eta-C5Me5)RhClL](+) 1-3, of which { 1, L = 2,2'-isopropylidenebis[4-isopropyl-2-oxazoline] and 3, L = 4-is opropyl-2-(2-pyridyl)-1,3-oxazoline} are structurally characterised by X-ray diffraction; treatment of these with AgSbF6 gives dications whi ch are enantioselective catalysts for the asymmetric Diels-Alder react ion between methacrolein and cyclopentadiene.