A synchrotron study of (2R,5′S)-5′-benzyl-5-bromo-6-methoxy- spiro-[indane-2,2′-piperazine]-3′,6′-dione dimethyl-formamide solvate

Synchrotron radiation was used to study the structure of the title compound, C₂₀H₁₉BrN₂O₃·C ₃H₇NO, which was obtained as fine fragile needle-shaped crystals by recrystallization from dimethyl-formamide (DMF), one mol-ecule of which is incorporated per asymmetric unit into the crystal. The compound adopts a compact closed conformation with the orientation of the benzyl group such that the aryl ring is positioned over the piperazinedione ring, resulting in a C_spiro⋯C_trans-C-C_Ph pseudo-torsion angle of-3.3 (3)°. The five-membered ring is present in an expected envelope conformation and the six-membered piperazinedione ring adopts a less puckered boat-like conformation. Reciprocal amide-to-amide hydrogen bonding between adjacent piperazinedione rings and C-H⋯O inter-actions involving DMF mol-ecules propagate in the crystal as a thick ribbon in the a-axis direction.