Construction of intermediate 86 Continued NaH, THF, 25C Me0C Dibal-H(1.5 eq), C. 78 C then MeO2C O (75% overall) 89 1. Dibal-H (2.2 eq). CH2C278°c 2. mCPBA, CH2Ch2,0C 31B2邮19)多 1.(COCI)2, DMSO, CH2Ch 78C, then Et3N 2. Ph P=CHCO, Me, PhH, 25C (75% overall) MeO2C CSA(cat ) CH2CL, 25C (ca. 10: 1 mixture of epoxide stereoisomers in favor (71%) 0f119 0Bn1.0:CH2Ch78℃c 1. TBAF. THF. 25oC then Ph3P: ther 2. (COCI)2, DMsO, NaBH4MeOH,25°C then Et3N 2. 2-methoxypropene, COmE MeO2c OTPS CSA(cat ) CH2Cl2, 25C 3. Ph3P=CHCO2 M (85% overall) CH2Ch2,25°C 93% overall (Eza.4:1)Construction of Intermediate 86 Continued O HO OTPS 90 Me OBn K TPSO H H CO2Me NaH, THF, 25 oC (92%) O OTPS 89 Me OBn K TPSO H H MeO2C O H Dibal-H (1.5 eq),CH2Cl2 , -78 oC; then Ph3P=CHCO2Me (75% overall) J O OTPS 118 Me OBn K H H O H J O TPS MeO2C 1. Dibal-H (2.2 eq), CH2Cl2 , -78 oC 2. mCPBA, CH2Cl2 , 0 oC (77% overall) O OTPS 119 Me OBn K H H O H J O TPS O HO (ca. 10:1 mixture of epoxide stereoisomers in favor of 119) 1. (COCl)2 , DMSO, CH2Cl2 , -78 oC, then Et3N 2. Ph3P=CHCO2Me, PhH, 25 oC 3. TBAF (1.2 equiv.), THF, 25 oC (75% overall) O OTPS 88 Me OBn K H H O H J HO O MeO2C O OTPS 120 Me OBn K H H O H J O MeO2C HO H I H CSA (cat.), CH2Cl2 , 25 oC (71%) 1. O3 , CH2Cl2 , -78 oC; then Ph3P; then NaBH4, MeOH, 25 oC 2. 2-methoxypropene, CSA (cat.), CH2Cl2 , 25 oC (85% overall) O OTPS 121 Me OBn K H H O H J O H I H O O O 122 Me OBn K H H O H J O H I H O O CO2Me 1. TBAF, THF, 25 oC 2. (COCl)2, DMSO, CH2Cl2, -78 oC; then Et3N 3. Ph3P=CHCO2Me, CH2Cl2, 25 oC (93% overall) (E:Z ca. 4:1)