2H-​Oxacyclotetradecino[​4,​3-​d]​oxazole-​2,​6,​8,​14(1H,​7H,​9H)​-​tetrone, 4-​ethyloctahydro-​11-​methoxy-​3a,​7,​9,​11,​13,​15-​hexamethyl-​1-​[1-​[(1R)​-​1-​(1,​8-​naphthyridin-​4-​yl)​ethyl]​-​3-​azetidinyl]​-​10-​[[3,​4,​6-​trideoxy-​3-​(dimethylam