ADDITIONS OF CARBON NUCLEOPHILES TO ACYCLIC IMINE COMPLEXES OF THE CHIRAL RHENIUM LEWIS-ACID [(ETA(5)-C5H5)RE(NO)(PPH3)](- CONTROLLING FACTORS IN 1,3-ASYMMETRIC INDUCTION AND SYNTHESES OF NON-RACEMIC ORGANIC AMINES() )
Ga. Stark et Ja. Gladysz, ADDITIONS OF CARBON NUCLEOPHILES TO ACYCLIC IMINE COMPLEXES OF THE CHIRAL RHENIUM LEWIS-ACID [(ETA(5)-C5H5)RE(NO)(PPH3)](- CONTROLLING FACTORS IN 1,3-ASYMMETRIC INDUCTION AND SYNTHESES OF NON-RACEMIC ORGANIC AMINES() ), Inorganica Chimica Acta, 269(1), 1998, pp. 167-180
Reactions of the racemic or enantiomerically pure benzaldehyde-derived
imine complex eta(5)-C5H5)Re(NO)(PPh3)(eta(1)-N-(CH3)=C(H)C6H5)] +TfO
- (1(+)TfO(-); 95:5 E/Z N=C isomers) and RLi (THF, -100 degrees C) giv
e amido complexes (eta(5)-C5H5)Re(NO)(PPh3)(N(CH3)CH(R)C6H5) (5) (R =
a/CH3, b/C = CSi(CH2CH3)(3), c/CH2Si(CH3)(3)) in quantitative NMR yiel
ds as 74-72:26-28 mixtures of Re,C configurational diastereomers. Thes
e labile adducts and TfOH react to give amine complexes [(eta(5)-C5H5)
Re(NO)(PPh3)(NH(CH3)CH(R)C6H5)] +TfO- (6(+)TfO(-)). Reaction of 6a(+)T
fO(-) (prepared from (R)-1(+)TfO(-)) and Et4N+CN- yields the cyanide c
omplex (R)-(eta(5)-C5H5)Re(NO)(PPh3)(CN) (85%, >98% ee) and amine (R)-
NH(CH3)CH(CH3)C6H5 (81%, 46% ee). Reactions of 1(+)TfO(-) and CN- give
similar amido complexes (85-84:15-16 Re,C diastereomers), but appear
reversible, with additions of CH3OTf affording 1(+)TfO(-). Reactions o
f the acetophenone-derived complex -C5H5)Re(NO)(PPh3)(eta(1)-N(CH3)=C(
CH3)C6H5)]+TfO- (4(+)TfO(-)) with C6H5CH2MgCl and (CH3)(3) SiCH2Li giv
e 41 and >99% deprotonation to the enamido complex (eta(5)-C5H5)Re(NO)
(PPh3)(N(CH3)C(C6H5)=CH2). Some addition occurs with C6H5CH2MgCl, and
CN-. NMR spectra (-100 degrees C) show Re-N=rotamers of 1,4(+)TfO(-),
and mechanisms of 1,3-asymmetric induction are analyzed in detail. (C
) 1998 Elsevier Science S.A.