Enantioselective preparation of substituted 2-hydroxypent-4-enes using optically-active catalysts

An enantioselective process for the preparation of homoallyl alcohol enantiomer of formula II ##STR15## wherein:

• X.sup.1, X.sup.2 and X.sup.3 are independently chosen from the group consisting of hydrogen, halogen, C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 haloalkyl, and haloaryl;
• and
• R.sup.1, R.sup.2, R.sup.3 and R.sub.4 are independently chosen from the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, phenyl, benzyl, substituted phenyl or benzyl wherein the substitution is C.sub.1 to C.sub.6 alkyl, halogen or C.sub.1 to C.sub.6 haloalkyl;
• and wherein R.sup.1 and R.sup.2 may be linked to form a 5 to 7 membered carbocyclic compound;
• which process comprises:
• reacting an aldehyde of formula III with an alkene of formula IV ##STR16## wherein X.sup.1, X.sup.2, X.sup.3 and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are as above, in the presence of an optically active organometallic catalyst complex comprising:
• a metal selected from the group consisting of titanoium, aluminum, zinc, iron, tin and zirconiunm and at least one ligand which is chiral and which is selected from the group consisting of halogens, alkyl groups, amines, alkoxy groups and aryloxy groups.