Smith Amos B 3rd; Cox Jason M; Furuichi Noriyuki; Kenesky Craig S; Zheng
Junying; Atasoylu Onur; Wuest William M Total synthesis of (-)-2-epipeloruside A. Organic letters (2008), 10(24), 5501-4.
BPS = tert-butyldiphenylsilyl
Horner-Wadsworth-Emmons Olefination
Mechanism
Stereochemical Outcome of HWE reaction
Usually favors formation of E-alkene
However….
Still and Gennari found that Z-alkenes could be produced if the highly
electron withdrawing trifluoroethylphosphonate is used as shown below.
SEMCl = trimethysilylethoxymethyl chloride
Brook Rearrangement