Abstract
-Lithiation of -(4-chlorophenethyl)- and -(4-methylphenethyl)-N, N-dimethylureas occurs using t-butyllithium (3.3 molar equivalents) in dry tetrahydrofuran at 60 to 0 on NH and on the next to the aryl ring. The lithium reagents generated in situ are trapped with several electrophiles (benzophenone, cyclohexanone, 2-butanone, 4-anisaldehyde, and benzaldehyde) to afford the corresponding substituted ureas in 79-96% yields. The experimental results were sustained by density functional theory calculations, which show that the side chain on the adjacent to the aryl ring is the most favorable site for the -lithiation of -(4-chlorophenethyl)-N, N-dimethylurea and -(4-methylphenethyl)-N, N-dimethylurea.