Catalytic asymmetric dihydroxylation of 1-substituted-1-ferrocenylethenes: an enantioselective entry to chiral tertiary ferrocenylcarbinols and ferrocenylalkylamines.

The Sharpless asymmetric dihydroxylation (AD) of 1-substituted-1-ferrocenylethenes takes place with good yields and with moderate to good enantioselectivities. The resulting 1-substituted-1-ferrocenyl-1,2-ethanediols are the first alpha-chiral tertiary ferrocenylcarbinols that have been prepared in optically active form. Their absolute configuration, ascertained by Induced Circular Dichroism (ICD), shows that in all cases the ferrocenyl moiety has the highest affinity for the SW binding pocket of the AD ligands. Depending upon the reaction conditions, significant racemization takes place during a side-chain azide nucleophilic substitution on 2-ferrocenyl-1,2-propanediol.