2,2-dimethyl-propionic acid-(2R,4S,6S,8S,10S)-8-(2-acetoxy-butyl)-4-(tert-butyl-dimethyl-silanyloxy)-1-hydroxy-1,7-dioxa-spiro[5.5]undec-2-ylmethyl ester

(1R)-1-[(4S,6R,8R,10S)-1-(tert-butyl-dimethyl-silanyloxy)-8-(tert-butyl-dimethyl-silanyloxymethyl)-4-methoxy-1,7-dioxa-spiro[5.5]undec-2-yl]-butan-2-ol