Z選択的ホルナー－エモンズ試薬
ジフェニルホスホノ酢酸エチル, ジ-o-トリルホスホノ酢酸エチルは安藤が開発したホルナー－エモンズ試薬で, Z選択的にオレフィン化を行うことができます。このオレフィン化反応は, 安価な四級アンモニウム塩ヒドロキシドを始めとする多様な塩基を用いることができ, 経済的で簡便なZ-不飽和エステルの導入法です。
“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.
