(Arene)ruthenium complexes with bis(oxazolines): Synthesis and applications as asymmetric catalysts for Diels-Alder reactions

Reaction of the dimers [RuCl2(arene)](2) (arene = benzene, p-cymene, mesity lene) with bis-(oxazolines) (N-N = bis(2-oxazoline) (box), 2,2-bis(2-oxazol inyl)propane (bop), 1,2-bis(2-oxazolinyl)benzene (benbox)) in the presence of NaSbF6 gives the complexes [RuCl(N-N)(arene)][SbF6] (1-8), which have be en fully characterized. Treatment of these cations with AgSbF6 generates di cations which in some cases are enantioselective catalysts for Diels-Alder reaction of methacrolein and cyclopentadiene. Two complexes, [RuCl(Pr-i-ben box)(p-cymene)][SbF6] (5) and [Ru(OH2)(Pr-i-bop)(mes)][SbF6](2) (10; mes = mesitylene), have been characterized by X-ray crystallography.