contiguous quaternary and tertiary stereogenic centers has been efficiently constructed via domino asymmetric Michael addition/transesterification reactions of azlactones with o‐hydroxychalcones using a quinine‐derived thiourea as bifunctional organocatalyst. Under mild reaction conditions, the optically active 3,4‐dihydrocoumarins were generally obtained in 63–96% yields with >20:1 dr and 81–96% ee.
通过
奎宁衍生的
硫脲作为双功能有机催化剂,通过氮杂内酰胺与邻羟基
查尔酮的多米诺不对称迈克尔加成/酯交换反应,已经有效地构建了一系列包含对映体的3,4-二氢
香豆素,这些连续的季
铵和叔立体构型中心。在温和的反应条件下,通常以63-96%的产率获得旋光的3,4-二氢
香豆素,dr > 20:1 ,ee达到81-96%。