8-Methoxy-1',3',3'-trimethyl-6-nitro-spiro[chromen-2,2'-indolin], Spiro[2H-1-benzopyran-2,2'-indoline],8-methoxy-1',3',3'-trimethyl-6-nitro, 8-methoxy-1',3',3'-trimethyl-6-nitro-spiro[chromene-2,2'-indoline], 1',3'-dihydro-8-methoxy-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-(2H)-indole], 8-methoxy-1',3',3'-trimethyl-6-nitro-1',3'-dihydrospiro[chromene-2,2'-indole], 1',3',3'-trimethyl-6-nitro-8-methoxyspiro-{2H-1}-benzopyran-2,2'-(2H)indole