Tulathromycin synthesis method of the marker residue

The present invention belongs to the technical field of chemical synthesis, in particular to a residue Tulathromycin marker, entitled 3-descladinosyl -9a- aza-9-deoxo-9-dihydro-homoerythromycin A -9a- synthetic chemical methods. Feature of the present invention is erythromycin A (E) oxime as a raw material, obtained after Beckmann rearrangement reaction A6,9- imino ether of erythromycin, i.e., by sodium borohydride reduction to give azithromycin, then off cladinose hydrolysis under acidic conditions to give 3-descladinose -9a- aza-9-deoxo-9-dihydro -9a- crude homoerythromycin A, prepared by repeated recrystallization after obtaining pure , HPLC purity of 99.5%. Simple process of the present invention, the reaction yields, high product purity, as indicated Tulathromycin residue candidate was the standard substance.