(S)-2-Oxotetra­hydro­furan-3-aminium bromide

In the title HBr salt of (S)-homoserine lactone, C(4)H(8)NO(2) (+)·Br(−), the five-membered ring has an envelope conformation, with the –CH(2)– C atom adjacent to the N-substituted C atom at the flap position. The four-atom mean plane (r.m.s. deviation = 0.005 Å) of the envelope forms a dihedral angle of 32.12 (9)° with the three-atom flap plane. The distorted square-pyramidal coordination about the anion involves five surrounding cations, with the square base defined by three N—H⋯Br hydrogen bonds [Br⋯N = 3.3046 (10), 3.3407 (12) and 3.3644 (13) Å] and near-contact with an H atom attached to C [Br⋯C = 3.739 (1) Å]. Another Br⋯C contact of 3.427 (1) Å defines the apex. There is also an N—H⋯O hydrogen bond present linking the cations.