(S) (S) O (R) (R) H 3 C (R) CH 3 O (R) O O O (S) CH 3 OH (R) (S) (R) (R) O (R) (S) O H 3 C CH 3 (S) (S) OH (R) CH 3 OH H 3 C (R) H 3 C HO H 3 C N CH 3 (S) N OH CH 3 H 3 C (E) O O O CH 3 NO