Triruthenium carbonyl clusters derived from chiral aminooxazolines:: synthesis and catalytic activity

Treatment of [Ru-3(CO)(12)] with the chiral aminooxazolines (+)-2-amino-(4R)-phenyl-2-oxazoline (H(2)amphox), (+)-2-amino-(4R,5S)-indanyl-2-oxazoline (H(2)aminox) and (+)-2-(2'-anilinyl)-(4R,5S)-indanyl-2-oxazoline (H(2)aninox) in THF at reflux temperature, affords the complexes [Ru-3(mu-H)(mu(3)-kappa(2)-Hox-N,N)(CO)(9)] (H(2)ox = H(2)amphox, 1; H(2)aminox, 2) and [Ru-3(mu-H)(mu-kappa(2)-Haninox-N,N)(CO)(9)] (3). In all cases, the activation of an N-H bond has occurred and the resulting amido fragment spans an edge of the metal triangle, while the N atom of the oxazoline ring is attached to the remaining metal atom (as in 1 and 2), or to one of the metal atoms of the bridged edge (as in 3). The use of 1-3 as catalyst precursors in the asymmetric hydrogen-transfer reduction of acetophenone and in the asymmetric cycloaddition of cyclopentadiene and acroleine is reported.