Strained, captodative benzylideneazetidinones were demonstrated to function as potent reaction partners in thermal [2+2] cycloadditions with nitro alkenes. The relief of strain during the cycloaddition could be leveraged to secure kinetic and thermodynamic stability for the aminonitrocyclobutane ring. Accordingly, this mild and robust procedure could be used to simplify the synthesis of azaspiro[3.3]heptanes, a motif that serves as a rigid piperidine bioisostere.