Asymmetric Synthesis of (1-Ferrocenylalkyl)amine and 1,1′-Bis(1-aminoalkyl)ferrocene Derivatives

The aldehydes 1 and 5 were converted to the corresponding SAMP hydrazones 2 and 6, respectively. Subsequent nucleophilic 1,2-addition of organolithium reagents to the C−N double bonds and cleavage of the N−N hydrazine bond using an excess of BH3·THF afforded (1-ferrocenylalkyl)amines (N-protection → 4) and 1,1′-bis(1-aminoalkyl)ferrocenes (N-protection → 8) in good overall yields (32−88%), with very high enantiomeric excesses (ee = 90−98%) and dl/meso ratios of up to 95:5.