Crystal structure of methyl (3RS,4SR,4aRS,11aRS,11bSR)-5-oxo-3,4,4a,5,7,8,9,10,11,11a-decahydro-3,11b-epoxyazepino[2,1-a]isoindole-4-carboxylate

Abstract

The title compound, C15H19NO4, is the a product of the esterification of the corresponding carbonic acid with methanol. The molecule comprises a fused tetracyclic system containing three five-membered rings (2-pyrrolidinone, tetrahydrofuran and dihydrofuran) 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 methylene C atoms lying above and below the mean plane defined by the remaining five atoms. The carboxylate substituent is rotated by 77.56(5)° with respect to the base plane of the tetrahydrofuran ring. In the crystal, the molecules are bound by weak C - H⋯O hydrogen-bonding interactions into puckered layers parallel to (001).