New chiral ferrocenyloxazolines: The first planar chiral triferrocenylmethane derivative and its use in asymmetric catalysis

New planar chiral enantiopure ferrocenyloxazolines have been prepared including ferrocenyldiphenylmethanol, diferrocenylphenylmethanol and triferrocenylmethanol derivatives (S,pR)-10 – (S,pR)-12, the latter being the first chiral triferrocenylmethanol derivative. The ferrocenyldiphenylmethanol derivative (S,pR)-10 has been crystallographically characterized. Asymmetric ethylation of some arylaldehydes using diethylzinc in the presence of the planar chiral triferrocenylmethanol derivative (S,pR)-12 afforded good yields and ees, which were higher than those obtained with related ferrocenyloxazolines.