N-But­oxy­carbonyl-5-oxo-l-proline ethyl ester

The mol­ecular structure of the title compound, C(12)H(19)NO(5), may be visualized as made up of two nearly perpendicular planes [dihedral angle = 87.39 (12)°] and its crystal structure is a good example of C—H⋯O inter­actions assuming significance in optimizing supra­molecular aggregation in crystals in a mol­ecule which is severely imbalanced in terms of donors to acceptor atoms. The pyrrolidine ring adopts a ((3) T (2)) twist conformation with puckering parameters Q = 0.2630 (4) Å and ϕ = 59 (9)°. The crystal structure features R (2) (4)(10) and R (3) (4)(26) ring motifs formed by four weak C—H⋯O inter­actions, leading to supra­molecular sheets lying parallel to the bc plane.