[(1AS,8S,8AR,8BS)-6,8A-DIMETHOXY-1,5-DIMETHYL-4,7-DIOXO-1,1A,2,4,7,8,8A,8B-OCTAHYDROAZIRENO[2',3':3,4]PYRROLO[1,2-A]INDOL-8-YL]METHYL CARBAMATE