CC[C@H]1[O:18][C:16](=[O:17])[C@H:15](C)[C@@H:14]([O:20][C@@H]2O[C@@H](C)[C@H](O)[C@@](OC)(C)C2)[C@H:13](C)[C@@H:12]([O:33][C@@H]2O[C@H](C)C[C@H](N(C)C)[C@H]2O)[C@@:11](O)(C)C[C@@H](C)CN(C)[C@H](C)[C@@H](O)[C@@]1(O)C.O.O.CC(OC(C)=O)=O.N#N.C(Cl)(Cl)Cl>N1C=CC=CC=1>[CH3:11][C:12]([CH2:13][C:14]([CH2:15][C:16]([OH:18])=[O:17])=[O:20])=[O:33]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.
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