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[5.3.0.0(1,5)]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 (X(3)), alternative photochemical pathways were observed.