Enantioselective Lithiation of N -Benzyl Ureas with a Chiral Lithium Amide: Dicyclopropylmethyl (Dcpm) as an Organolithium-Resistant Nitrogen Protecting Group

-benzyl urea derivatives with a chiral lithium amide base leads to enantioselective deprotonation, generating benzyllithiums that can be trapped by reactive electrophiles, giving products in good enantiomeric excess. Sterically hindered nitrogen substituents were necessary for good enantioselectivity, and using the dicyclopropylmethyl (Dcpm) group as a new organolithium-resistant, acid-labile protecting group both facilitated the enantioselective deprotonation and enabled the synthesis of carbamate-protected primary chiral benzylamines after deprotection and solvolysis.