Josamycin; Josamycin Propionate EP Impurity E

(2S,3S,4R,6S) -6- (((2R,3S,4R,5R,6S) -6- (((4R,5S,6S,7R,9R,10R,11E,13E,16R) -4-acetoxy-10-hydroxy-5-methoxy-9,16-dimethyl-2-oxo-7- (2-oxoethyl) oxacyclohexadeca-11,13-dien-6-yl) oxy) -4- (dimethylamino) -5-hydroxy-2-methyltetrahydro-2H-pyran-3-yl) oxy) -4-hydroxy-2,4-dimethyltetrahydro-2H-pyran-3-yl 3-methylbutanoate