(R)-(pivaloyloxy)methyl 2-((R,Z)-4-(2-aminothiazol-4-yl)-13,13-dimethyl-5,8,12-trioxo-2,9,11-trioxa-3,6-diazatetradec-3-en-7-yl)-5-((Z)-2-(4-methylthiazol-5-yl)vinyl)-3,6-dihydro-2H-1,3-thiazine-4-carboxylate