First representative of 6b,9-epoxyisoindolo-[2,1-a]quinazoline-10-carboxylic acids

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).

Crystal strucutre of rac-methyl (11aR*,12S*,13R*,15aS*,15bS*)-11-oxo-11,11a,12,13-tetra-hydro-9H,15bH-13,15a-ep-oxy-isoindolo[1,2-c]pyrrolo[1,2-a][1,4]benzodiazepine-12-carboxyl-ate

The title compound, C₂₁H₁₈N₂O₄, obtained as a racemate, contains a novel heterocyclic system, viz. isoindolo[1,2-c]pyrrolo­[1,2-a][1,4]benzodiazepine. The central diazepane ring has a distorted boat conformation with two phenyl­ene-fused and one methine C atom deviating by 0.931 (1), 0.887 (1) and 0.561 (1) Å, respectively, from the mean plane of the rest of the ring. The γ-lactone ring has an envelope conformation, with the C atom opposite to amide bond deviating by 0.355 (1) Å from its plane. In the crystal, mol­ecules form centrosymmetric dimers through pairs of C—H⋯O hydrogen bonds.