Addition of organolithium reagents to Ahc methyl ester. An approach to new α-amino ketones

We have developed a versatile methodology to obtain α-amino ketones by acylation of methyl N-benzoyl-7-azabicyclo[2.2.1]heptane-1-carboxylate () with organolithium reagents. The reaction proceeds via a stable tetrahedral intermediate. When methyl ester was treated under the same conditions but with a different work up procedure (careful addition of saturated NH4Cl), we observed by 1H NMR spectroscopy that a new compound had appeared in the crude reaction mixture corresponding to a hemiacetal.