Construction of intermediate 87 Continued ( Construction of Intermediate 103) Br Et, N,4-DMAP (cat ) CHCl2,25℃C Nal (excess), 18-crown (CH32CO.25℃C 2C2,-30℃C 103O Me O SOBr2 ZnBr2 , 55 oC Br O Me Br O Me OH Et3N, 4-DMAP (cat.), CH2Cl2 , 25 oC O O Me Me Br O 142 143 144 NaI (excess), 18-crown-6, (CH3 )2CO, 25 oC O O Me Me I O 145 BF3 OEt2 , CH2Cl2 , -30 oC O O O Me I Me 103 Construction of Intermediate 87 Continued (Construction of Intermediate 103)