Method for synthesizing telithromycin key intermediate 5-deoaminyl-6-O-methylerythromycin

The invention provides a method for synthesizing a telithromycin key intermediate 5-deoaminyl-6-O-methylerythromycin. The method comprises the following steps of: adding a precursor, namely an oxime protected object of clarithromycin into a solvent, adding a certain amount of acid, and removing cladinose at a certain temperature; maintaining a certain pH value and certain temperature, dripping a deoximation agent and acid, and controlling the pH value and maintaining for certain time; and finally, regulating the pH value by using alkali to obtain the 5-deoaminyl-6-O-methylerythromycin. In the process, the pH values during acidolysis and deoximation are controlled respectively, and the acidolysis and deoximation are continuously finished; the process is simple, the yield and the purity are high, and the cost is low; and the precursor of the clarithromycin is taken as a raw material, and the intermediate and the clarithromycin can be coproduced, so the method has industrialized prospect.