(2R,3R,4R,5R)-3,4-dibenzyloxy-N-benzyloxycarbonyl-2-tert-butyldiphenylsilyloxymethyl-5-[(1'S,2'R)-1'-2'-dihydroxy-3'-oxobutyl]pyrrolidine

(2R,3R,4R,5R)-3,4-dibenzyloxy-N-benzyloxycarbonyl-2-tert-butyldiphenylsilyloxymethyl-5-[(1'R,2'S)-1'-2'-dihydroxy-3'-oxobutyl]pyrrolidine

(1S,2R,5R,6R,7R,7aR)-6,7-dibenzyloxy-5-tert-butyldiphenylsilyloxymethyl-1,2-dihydroxypyrrolizidin-3-one

(1R,2S,5R,6R,7R,7aR)-6,7-dibenzyloxy-5-tert-butyldiphenylsilyloxymethyl-1,2-dihydroxypyrrolizidin-3-one

(1R,2R,5R,6R,7R,7aR)-1,2-dibenzyloxy-3-tert-butyldiphenylsilyloxymethyl-6,7-dihydroxypyrrolizidine