A one‐pot two‐step enzymatic strategy has been designed for the production of optically active γ‐ and δ‐lactams in aqueous medium under mild conditions. The approach is based on the biotransamination of ethyl or methyl keto esters bearing different alkyl or aryl substitution patterns at α‐position to the ketone functionality. In this manner, the keto esters were transformed into the corresponding amino esters with excellent conversions, which underwent spontaneous cyclisation in the reaction medium without addition of external reagents. Depending on the transaminase selectivity, both lactam enantiomers can be obtained, so initial enzyme screenings were performed using commercially available and made in house enzymes. Reaction conditions were optimised focusing on the substrate concentration, temperature and ratio of amine donor vs acceptor. Thus, ten γ‐ and δ‐lactams were obtained in good to high isolated yields (70–90%) and excellent selectivities (94–99%) after one or two days at 30 or 45 °C.

中文翻译：

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将γ-和δ-酮基酯转化为旋光内酰胺。级联过程中的转氨酶

设计了一种一锅两步的酶促策略，用于在温和条件下在水性介质中生产旋光性γ-和δ-内酰胺。该方法基于乙基或甲基酮酯的生物转氨作用，该酯在酮官能团的α位置带有不同的烷基或芳基取代模式。以这种方式，将酮酯以优异的转化率转化为相应的氨基酯，其在反应介质中自发环化而无需添加外部试剂。根据转氨酶的选择性，可以获得两种内酰胺对映体，因此使用市售的并在内部进行的初始酶筛选酶。优化反应条件，着重于底物浓度，温度和胺供体与受体的比例。因此，在30或45°C下经过1天或2天后，获得了十种γ-和δ-内酰胺，分离收率良好至高（70-90％），选择性极好（94-99％）。