The Olefin Synthesis from β-Hydroxyalkylphosphonates Induced by Fluorides or Relatively Weak Bases

Article abstract of DOI:10.1246/bcsj.71.209

β-Hydroxyalkylphosphonates, which were prepared readily from alkylphosphonates and carbonyl compounds, were treated with a fluoride ion such as CsF or with relatively weak bases such as K₂CO₃ in N,N-dimethylformamide to give the corresponding olefins in good yields. One molar equivalent of water to bases is effective for increasing the yields of olefins. The stereochemistry of erythro-dimethyl (2-hydroxy-1-methyl-2-phenyl)ethylphosphonate was determined by X-ray crystallographic analysis. Use of threo-isomer gave (E)-olefin exclusively, while that of erythro-enricned isomer afforded predominantly (Z)-olefin, indicating that the present olefination proceeds stereospecifically in a manner of syn-elimination.