Compound 46

8'-(tert-butyl) 1-ethyl 3,3-dimethyl-4-oxa-5,8'-diazaspiro[bicyclo[3.2.0]heptane-6,3'-bicyclo[3.2.1]octane]-1,8'-dicarboxylate

From: Synthesis of azetidines via visible-light-mediated intermolecular [2+2] photocycloadditions