Abstract
Different protected C
2-symmetric
1,n-diamines (R,R)- or (S,S)-4 and 8 can be prepared in high diastereo- and
enantiomeric purity by nucleophilic 1,2-addition of organocerium
reagents to the CN double bond of bis-SAMP-hydrazones
(S,S)-2a∠c.
The chiral starting materials are readily available by reaction
of dialdehydes with the enantiopure hydrazine 1-amino-2-methoxymethylpyrrolidine
(SAMP). Reductive NN bond cleavage of the hydrazines (R,R,S,S)- or (S,S,S,S)-3 and 7 afforded
the title compounds (de 72∠98%,
ee 96∠98%).
The novel entry for the asymmetric synthesis of N-protected C
2-symmetric diamines presented
here is highly flexible, as both the distance of the amino functions
and the introduced residues R can be varied.
Key words
amines - hydrazones - nucleophilic additions - asymmetric synthesis - cerium