(4R,5R,6S)-6-(tert-Butyl-dimethyl-silanyloxy)-2,2,4-trimethyl-1,3-dioxa-spiro[4.4]nonan-7-one

(1S,4R,7R,8R)-8-Hydroxymethyl-7-((4R,5R)-2,2,5-trimethyl-[1,3]dioxolan-4-yl)-bicyclo[2.2.2]oct-5-en-2-one

2,2-Dimethyl-propionic acid (1R,2R,3R,4S)-8-oxo-3-((4R,5R)-2,2,5-trimethyl-[1,3]dioxolan-4-yl)-bicyclo[2.2.2]oct-5-en-2-ylmethyl ester

2,2-Dimethyl-propionic acid (1S,2R,3R,4S,7R)-7-hydroxy-5-oxo-3-((4R,5R)-2,2,5-trimethyl-[1,3]dioxolan-4-yl)-bicyclo[2.2.2]oct-2-ylmethyl ester

(1S,4R,7R,8R)-8-(4-Methoxy-benzyloxymethyl)-7-((4R,5R)-2,2,5-trimethyl-[1,3]dioxolan-4-yl)-bicyclo[2.2.2]oct-5-en-2-one