An Intramolecular [2 + 2] Photocycloaddition Approach to Conformationally Restricted Bis-Pyrrolidines

With N-Boc-protected 4-(allylaminomethyl)-2­(5H)­furanones as starting materials, a photochemical approach is presented to give 3,9-diazatricyclo­[5.3.0.01,5]­decanes as conformationally restricted bis-pyrrolidines. The products are orthogonally protected at the two nitrogen atoms and exhibit, depending on the substitution pattern at positions C5, C6, and C7, latent C2 symmetry. When the furanones had a phenyl group at the 3-position (X3), alternative photochemical pathways were observed.