Crystal structure of methyl (3RS,4SR,4aRS,11aRS,11bSR)-5-oxo-3,4,4a,5,7,8,9,10,11,11a-deca-hydro-3,11b-ep-oxy-azepino[2,1-a]iso-indole-4-carboxyl-ate.

The title compound, C15H19NO4, is the a product of the esterification of the corresponding carbonic acid with methanol. The mol-ecule comprises a fused tetra-cyclic system containing three five-membered rings (2-pyrrolidinone, tetra-hydro-furan and di-hydro-furan) and one seven-membered ring (azepane). The five-membered rings have the usual envelope conformations, with the quaternary C atom being the flap atom for the 2-pyrrolidinone ring, and the ether O atom being the common flap atom for the remaining rings. The seven-membered azepane ring adopts a chair conformation with the methine and middle methyl-ene C atoms lying above and below the mean plane defined by the remaining five atoms. The carboxyl-ate substituent is rotated by 77.56 (5)° with respect to the base plane of the tetra-hydro-furan ring. In the crystal, the mol-ecules are bound by weak C-H⋯O hydrogen-bonding inter-actions into puckered layers parallel to (001).