STRUCTURAL STUDIES OF MITOMYCINS .4. STRUCTURE OF ALBOMITOMYCIN-A

[1S-(1-alpha,2-alpha,4-beta,5-beta,6-alpha,6a-alpha,10aR)]-2,3,6,6a,7,10-Hexahydro-1,2,5-metheno-5,8-dimethoxy-9-methyl-7,10-Hexahydro-1,2,5-metheno-5,8-dimethoxy-9-methyl-7,10-dioxo-1H,5H-imidazo[2,1-i]indol-6-ylmethyl carbamate, C16H19N3O6, M(r) = 351.36, monoclinic, P2(1), a = 10.605 (1), b = 8.342 (2), c = 9.4889 (7) angstrom, beta = 106.416 (7)-degrees, V = 805.2 (3) angstrom-3, Z = 2, D(x) = 1.45 g cm-3, Mo K-alpha, lambda = 0.71073 angstrom, mu = 1.296 cm-1, F(000) = 372, T = 293 K, wR = 0.044 for 1427 observed reflections with F > 3-sigma-(F). The title compound is one of the minor constituents from the fermentation broth of mitomycin A. The structure has a quite unusual fused-ring system for mitomycins. The quinone ring which is one of the important structural characteristics of the mitomycin family is reduced to a dihydroquinone in the title compound.