New antibiotics, enaminomycins A, B and C. III. The structures of enaminomycins A, B and C.

The structures of enaminomycins A and B were determined by their physico-chemical properties and X-ray crystallographic analyses to be 4-amino-2,5-dioxo-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid and 2-oxo-4-amino-5-hydroxy-5-acetonyl-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid, respectively. The structure of enaminomycin C was also determined by the analysis of NMR spectrum and other physico-chemical properties to be 2-oxo-4-amino-5-hydroxy-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid.