“Highly Selective Synthesis of Z-Unsaturated Esters by Using New Horner−Emmons Reagents, Ethyl (Diarylphosphono)acetates”
K. Ando, J. Org. Chem. 1997, 62, 1934. DOI: 10.1021/jo970057c
New Horner−Emmons reagents, ethyl (diarylphosphono)acetates 1, were prepared from triethyl phosphonoacetate, PCl5, and the corresponding phenols. The reaction of 1 with several kinds of aldehydes in the presence of Triton B or NaH in THF solvent revealed that these reagents are useful for the synthesis of Z-unsaturated esters. Among the reagents examined, ethyl(di-o-tolylphosphono)-, [bis(o-ethylphenyl)phosphono]-, and [bis(o-isopropylphenyl)phosphono]acetates (1k−m) were found to be the most effective, giving Z-unsaturated esters with 93−99% selectivity.