ERYTHROMYCIN A DERIVATIVE AND ITS PRODUCTION

PROBLEM TO BE SOLVED: To obtain an erythromycin A derivative useful as an intermediate for producing an antibiotic medicine 6-O-methylerythromycin A by protecting the 9-position of erythromycin A and selectively methylating the hydroxyl group at the 6-position. SOLUTION: This new erythromycin derivative is shown by formula I [R1 is H or a 1-6C alkyl; R2 is a 1-6C alkyl or a (substituted) alkyl; R1 and R7 are bonded to form a 3-10C alkylene ring or the like; R4 is H or a substituted silyl group] and is usefulas an intermediate for producing an antibiotic medicine 6-O-methylerythromycin A (clarithromycin), etc. This compound is obtained by converting erythromycin A into erythromycin A 9-hydrazone, converting the hydrazone into an erythromycin A 9-azine derivative of formula II, protecting the hydroxyl groups at the 2'- and the 4'-positions by silylation and methylating the hydroxyl group at the 6-position of the resultant substance.