ENANTIOSELECTIVE ADDITION OF ALKYLLITHIUM REAGENTS TO ALDEHYDES INDUCED BY CHIRAL LITHIUM ALKOXIDES

Enantioselective induction by some chiral lithium alkoxides in the addition of methyllithium to benzaldehyde has been examined. A detailed study of 2-substituted lithium 1-phenyl-2-(N,N-dimethylamino)ethoxides in the addition of achiral alkyllithium reagents to aldehydes in THF and diethyl ether at -78 degrees C has been carried out. The ee's are generally higher in the former solvent. The configuration of the newly formed chiral center is opposite to that of the 1-carbon of the alkoxide and independent of that of its 2-carbon atom. The ee of the product is generally increased by increasing the size of 2-substituent Enantioselectivity is decreased by the addition of LiCl and LiClO4 but is little affected by the presence of the predominant enantiomer of the lithium alkoxide produced in the reaction.