Gravar-mail: Crystal strucutre of rac-methyl (11aR*,12S*,13R*,15aS*,15bS*)-11-oxo-11,11a,12,13-tetra­hydro-9H,15bH-13,15a-ep­oxy­isoindolo[1,2-c]pyrrolo[1,2-a][1,4]benzodiazepine-12-carboxyl­ate