The title compound, (1aS)-6-amino-8-{[(aminocarbonyl)-oxy]methyl}-1, b
-hexahydro-8a-methoxy-5-(phenylthiomethyl)azirino [2',3':3,4]pyrrolo[1
,2-a]indole-4,7-dione, C21H22N4O5S, is a C6-substituted methyl mitomyc
in C which possesses potent antitumor activities. The N4 atom is more
pyramidal than the corresponding atom in both mitomycin C anhydride an
d mitomycin C dihydrate.