(R)-5-((S)-3-Benzenesulfonyl-6-{(6S,7R)-7-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-6,7-dimethyl-1,4-dioxa-spiro[4.5]dec-6-yl}-2-methyl-4-oxo-hexyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid benzyl ester

(-)-3,5-dinitro-benzoic acid (2R,4S,5S,6R,7S)-7-methoxymethoxymethyl-4,7-dimethyl-6-(2-oxoethyl)-1-oxaspiro[4.4]non-2-ylmethyl ester

(+)-3,5-dinitrobenzoic acid (2R,4S,5S,6S,7S)-7-methoxymethoxymethyl-4,7-dimethyl-6-(2-oxoethyl)-1-oxaspiro[4.4]non-2-ylmethyl ester

(+)-3,5-dinitrobenzoic acid (2R,4S,5R,6R,7S)-7-methoxymethoxymethyl-4,7-dimethyl-6-(2-oxoethyl)-1-oxaspiro[4.4]non-2-ylmethyl ester

(-)-3,5-dinitro-benzoic acid (2R,4S,5S,6R,7S)-6-(2-hydroxyethyl)-7-methoxymethoxymethyl-4,7-dimethyl-1-oxaspiro[4.4]non-2-ylmethyl ester