Em. Cayuela et al., Synthesis of enantiopure 1,1 '-(1-dimethylamino-propanediyl)ferrocene via a highly diastereoselective imine reduction, TETRAHEDR-A, 11(4), 2000, pp. 861-869
1,1'-(1-Oxo-propanediyl)ferrocene 4 reacts with (S)-(-)-1-(1-naphthylethyl)
amine to give the corresponding syn imine exclusively which undergoes a hig
hly diastereoselective reduction with sodium borohydride to give the diaste
reomerically pure (R,S)-(+)-amine 6. Conversion of 6 leads in three steps t
o the final product (R)-(+)-1,1'-(1-dimethylamino-propanediyl)ferrocene 2 i
n 53% overall yield (based on J) and in >98% e.e. Use of (S)-(-)1-phenyleth
ylamine as the chiral auxiliary leads to an 84: 16 mixture of syn),) and an
ti imines. After reduction and separation of the resulting diastereomers th
e major isomer (R,S)-(-)-10 can also be converted to the final product (R)-
(+)-2 in 55% overall yield (based on 4) and in >98% e.e. (C) 2000 Elsevier
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