New cinchonium salts bearing 5,5′-bis(methyl)-2,2′-bipyridine 1 group show solvent/substitution-dependent reversal of enantioselectivity. When used as chiral phase transfer catalyst in the asymmetric Michael addition of chalcones with diethylmalonate within two hours these catalysts result in high chemical yield (up to 98%) and enantiomeric excess (up to 99%) under lower concentrations of base and cold
带有5,5'-双(甲基)-
2,2'-联吡啶1基团的新菊苣盐显示出对溶剂/取代基的对映选择性逆转。当在两个小时内将
查尔酮与
丙二酸二乙酯不对称迈克尔加成
查耳酮时用作手性相转移催化剂时,这些催化剂在较低的碱和冷条件下会导致较高的
化学收率(最高98%)和对映体过量(最高99%)。