Scheme 1. Synthesis of Compounds 8–13a.

a Reagents and conditions: (i) succinic anhydride, DMAP, dry CH2Cl2, reflux; (ii) DCC/DMAP, dry CH2Cl2, 1 for 8–10, 2 for 11–13. The definitions of X and Y are indicated in Chart 1.

a Reagents and conditions: (i) succinic anhydride, DMAP, dry CH2Cl2, reflux; (ii) DCC/DMAP, dry CH2Cl2, 1 for 8–10, 2 for 11–13. The definitions of X and Y are indicated in Chart 1.