Vinorelbine EP Impurity F/(2S,6R,8S)-8-((3aR,3a1R,4R,5S,5aR,10bR)-4-acetoxy-3a-ethyl-5-hydroxy-8-methoxy-5-(methoxycarbonyl)-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-4-ethyl-8-(methoxycarbonyl)-2-methyl-2,3,6,7,8,9-hexa
