4-Fluoro-β-(4-fluorophenyl)-l-phenylalanine 1 was synthesized by the asymmetric phase-transfer catalyzed alkylation of tert-butyl glycinate-benzophenone Schiff base using the cinchona alkaloid derived catalyst 6. Upon scaling, it was observed that to achieve high levels of enantioselectivity, it was necessary to add the catalyst or base last. From these studies, insight into the stability of the catalyst 6 under the reaction conditions was gained.

中文翻译：

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不对称相转移催化烷基化合成4-氟-β-（4-氟苯基）-1-苯基丙氨酸：规模合成和催化剂稳定性

通过使用金鸡纳生物碱衍生催化剂6通过甘氨酸叔丁酯-二苯甲酮席夫碱的不对称相转移催化烷基化反应合成了4-氟-β-（4-氟苯基）-1-苯丙氨酸1。在结垢时，观察到要实现高水平的对映选择性，必须最后添加催化剂或碱。从这些研究中，获得了在反应条件下催化剂6的稳定性的见解。