O CH 3 H 3 C OH O H 3 C HO CH 3 O N H 3 C CH 3 CH 3 N O O O CH 3 CH 3 O H 3 C CH 3 H 3 C CH 3 OH HO CH 3 (R) (S) (R) (S) (R) (R) O (S) (R) (R) (R) (S) (R) O (S) (R) (R) O (R) (S) (S) (E)