The application of chiral group IV ansa-metallocenes to asymmetric synthesis

Ethylenebis(;The resolution of rac-57 and rac-66d with enantiomerically enriched binaphthol was examined. To demonstrate that the reaction of rac-66d with binaphthol was enantiospecific, the 1:1 reaction of rac-66d and rac-binaphthol was performed. A single product was obtained: rac-73, which crystallized from toluene/iso-octane as monoclinic crystals. A new direct route to enantiomerically enriched ansa-titanocenes was demonstrated.;The reactions of achiral, unbridged allyltitanocenes with aldehydes are explained by the six-membered cyclic, chairlike transition state model. The diastereoselectivity of the reaction increases with the increasing steric bulk of both the titanocene substituent and the aldehyde substituent. The diastereoselectivity of the reaction of crotyltitanocene 46b with substituted aromatic aldehydes shows a resonance effect and a change in mechanism.;The reaction of aldehydes with chiral ansa-titanocene allyl compounds yields homoallylic alcohols in low to moderate enantiomeric excess. Reagents without substituents at C3 of the ;The X-ray structures of racemic-ethylenebis(...