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

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

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

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

(6R,8R,10R)-10-(tert-butyl-dimethyl-silanyloxy)-2-(2-hydroxy-butyl)-8-hydroxymethyl-1,7-dioxa-spiro[5.5]undec-2-en-4-one