Methoxy-acetic acid 2-[(2S,4S,6R,8S,10S)-4-acetoxy-8-((3R,4S,5R)-4-acetoxy-6-hydroxy-3,5-dimethyl-2-methylene-hexyl)-10-hydroxy-10-methyl-1,7-dioxa-spiro[5.5]undec-2-yl]-ethyl ester