An ester exchange reaction of β-butoxy-β-acyloxyvinyl-λ3-iodane with lithium bases (ROLi and nBuLi) efficiently generates highly labile monoester iodonium ylide at low temperature. The iodonium ylide generated in situ cleanly undergoes Darzens condensation with aromatic aldehydes to afford trans-epoxy ester selectively.
β-丁氧基-β-酰氧基
乙烯基-λ3-
碘与
锂碱(ROLi 和 nBuLi)的酯交换反应可在低温下有效地生成高度不稳定的单酯
碘鎓叶立德。原位产生的
碘鎓叶立德与芳香醛完全进行 Darzens 缩合,以选择性地提供反式环氧酯。