(S)-1,5-Dibenzyl-3-tert-butylimidazolidin-4-one

The title compound, C21H26N2O, was obtained as an unexpected by-product when attempting to prepare (S)-2-benzyl-N-tert-butyl-1,2,3,4-tetrahydroisoquinoline-3-carboxamide from (S)-2-benzylamino-N-tert-butyl-3-phenylpropanamide and dimethoxymethane. The molecules are linked by weak C—H...O hydrogen bonds, generating linear chains parallel to the b axis. C—H...π interactions provide further stability for the crystal structure. The planes of the two phenyl rings make a dihedral angle of 84.1 (1)°. The absolute configuration was known from the starting material.