Trifluoro‐ and trichloroacetamides serving as pronucleophiles undergo enantioselective Lewis base catalyzed N ‐allylation with Morita‐Baylis‐Hillman carbonates to produce enantioenriched β‐amino acid derivatives. The reactions proceed as a kinetic resolution to give the allylation products and the remaining carbonates in good yields and high enantioselectivity. The obtained products are amenable to diastereoselective derivatization to produce a library of spiro‐isoxazoline lactams.