... OR, OR, OSiPh,t-Bu e OTH P f Br - B r Ph3P+ g phcH20fi +phTfloR - , P h CH 2 0 g H 3 l2 + l4 chrom- RO OTHP E a: Z b: E E E a: Z b: E ... 78OC to rt (e) DHP, PPTS, CH2C12, rt (82%) (f) (i) BrPh3P+CH2CH3, HMDSK, toluene, THF, 0°C (ii) 13, THF, 48 h, rt (81%) (g) (i) 14 ...