THE OLEFIN SYNTHESIS FROM BETA-HYDROXYALKYLPHOSPHONATES INDUCED BY FLUORIDES OR RELATIVELY WEAK BASES

beta-Hydroxyalkylphosphonates, which were prepared readily from alkylp hosphonates and carbonyl compounds, were treated with a fluoride ion s uch as CsF or with relatively weak bases such as K2CO3 in N,N-dimethyl formamide 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 ana lysis. Use of threo-isomer gave (E)-olefin exclusively, while that of erythro-enriched isomer afforded predominantly (Z)-olefin, indicating that the present olefination proceeds stereospecifically in a manner o f syn-elimination.