(2R,5S)-5-Benzyl-2,3-dimethyl-4-oxo-2-phenyl-imidazolidin-1-ium chloride.

The title hydro-chloride salt, C(18)H(21)N(2)O(+)·Cl(-), is an imidazolidinone catalyst, which was derived from L-phenyl-alanine through cyclization with acetophenone. The imidazolidinone compound has a five-membered heterocyclic ring including two chiral centres. The imidazolidinone ring displays an envelope conformation, with the flap protonated N atom lying 0.497 (3) Å above the mean plane of the remaining four atoms. In the crystal structure, one-dimensional supra-molecular chains parallel to the crystallographic 2(1) screw axis are formed by N-H⋯Cl hydrogen bonds involving the NH(2) (+) and Cl(-) groups. Intra-molecular N-H⋯Cl inter-actions are also present.