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