Highly Selective Synthesis of Z-Unsaturated Esters by Using New Horner-Emmons Reagents, Ethyl (Diarylphosphono)acetates.
New Horner-Emmons reagents, ethyl (diarylphosphono)acetates 1, were prepared from triethyl phosphonoacetate, PCl(5), 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.
Ando
Kaori
K
College of Education, University of the Ryukyus, Nishihara-cho, Okinawa 903-01, Japan.