HH SR OH OHOH O OH OH O 2, 3-syn, 3, 4-syr H SR OHOH O 2, 3-syn 2,3-syn,3,4s SR 2,3-syn,3O O OH H O OH H H OH H OH OH O OH OH SR O 2,3-syn, 3,4-syn OH O H O OH OH SR O O H O H 2,3-syn O OH O H SR O 2,3-syn, 3,4-syn O O H O H 2,3-syn, 3,4-anti