Stereodivergent Synthesis of β-Lactams Using Thermal Rearrangement of Aminocyclobutenones

In the present study, the stereodivergent synthesis of both cis- and trans-beta-lactams is presented using the following three reactions: iminocyclobutenone formation, chemoselective reduction of imino groups, and thermal rearrangement of aminocyclobutenones as crucial steps, in which the starting materials, iminocyclobutenones, were readily synthesized using conjugate addition reactions of alkynyl imines with ketene silyl acetals in good yields.