Nitrogen → 3,5-Dioxohexanoic acid

To a solution of 1.5 g (0.002 mole) of N-methyl-11-aza-10-deoxo-10-dihydro erythromycin A in 20 ml of pyridine there were added 10 ml (0.106 mole) of acetanhydride and it was stirred in a N2 -stream for 36 hours while heating at 60° to 80° C. The reaction was stopped by the addition of approx. 100 cm3 of ice and the product was isolated by the extraction with chloroform (4×30 ml) at a pH of 8.5. The combined chloroform extracts were washed with a 5% w./w. NaHCO3 solution (2×50 ml) and dried over K2CO3. Subsequently to the evaporation of chloroform the residual precipitate was dried with benzene, whereupon it was purified by chromatography on a silica gel column, system chloroform:methanol=9:1. There were obtained 0.89 g (51%) of analytically pure triacetate.