The synthesis of a large number of β- and β,β-substituted keto esters was successful by the use of the Knoevenagel condensation reaction. The stereoselectivity of these reactions was improved by alteration of various substituent groups. Although there were few examples of complete Z selectivity, the use of tert-butyl acetoacetate with either aromatic or aliphatic aldehydes afforded Z selectivity. The selective reductions of these substituted keto esters was successfully achieved by using a combination of NaBH4 and CeCl3·7H2O or Yb(OTf)3, which allowed a facile synthesis of a large number of stereochemically pure substituted Morita–Baylis–Hillman adducts, including β,β-substituted adducts.
大量β-和β,β-取代酮酯的合成成功地通过Knoevenagel缩合反应实现。通过改变各种取代基团来改善这些反应的立体选择性。尽管完全Z选择性的例子很少,但是使用叔丁基乙酰乙酸酯与芳香族或脂肪族醛可以获得Z选择性。这些取代酮酯的选择性还原成功地通过使用NaBH4和CeCl3·7H2O或Yb(OTf)3的组合实现,从而实现了大量立体化纯净的取代Morita–Baylis–Hillman加合物的简便合成,包括β,β-取代加合物。