Absolute configuration amine metal complexes

Absolute configuration amine metal complexes, 26 Acetaldehyde oximes... 

Unfortunately, the complexes underwent facile epimerization under the condi tions of catalytic hydroamination via reversible protolytic cleavage of the metal cyclopentadienyl bond (Scheme 11.7) [36, 38 40]. Thus, the product enantioselec tivity was limited by the catalyst s epimeric ratio in solution and the absolute configuration of the hydroamination product was independent of the diastereomeric purity of the precatalyst. Complexes with a (+) neomenthyl substituent on the cyclopentadienyl ligand generally produced the R) ( ) pyrrolidines, whereas ( ) menthyl and ( ) phenylmenthyl substituted complexes yielded the (S) (+) pyrrolidines, which is in agreement with the proposed stereomodel and solution studies on the equilibrium epimer ratios in the presence of simple aliphatic amines. 

The atropisomeric dinaphthophosphepins ( )-(35) (R = Me, Ph) can be prepared from 2,2 -dimethyl-l,r-dinaphthyl by lithiation and addition of the respective dichlorophosphine <94TA5ll, 94JOC6363>. The resolutions of ( )-(35) (R = Me, Ph) were accomplished by the method of metal complexation with use of an optically active ortho-metallated palladium(II)-amine complex. The absolute configuration of (S)-(—)-(35) (R = Ph) was determined from the x-ray crystal structure of (36). The optically active phosphepin in conjunction with rhodium(I) is an effective auxiliary for the asymmetric hydroformylation of styrene. 

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