(R)- and (S)-enantioselective lithiation of (arene)tricarbonylchromium acetal complexes with chiral alkyllithiums
作者:Michael J. Siwek、James R. Green
DOI:10.1039/cc9960002359
日期:——
The lithiation of (arene)tricarbonylchromium acetal complexes with the organolithium reagents derived from (1R)-menthyl chloride and (1R)-8-phenylmenthyl chloride occurs at the pro-R site (up to 70% ee) and the pro-S(up to 80% ee), respectively.
addition reactions with eight chiral Li-amide bases, 1 - 8, and five [Cr(arene)(CO)3] complexes, 9 - 13, were investigated. Restriction of conformational freedom in the chiral Li-amide base Li-1, in general, did not result in an increase in asymmetric induction. A new route to enantiomerically enriched (75 - 92%) planarchiral ortho-substituted benzaldehyde complexesvia enantioselective lithiation of