The development of catalysts serves as the cornerstone of innovation in synthesis, as exemplified by the recent discovery of photoenzymes. However, the repertoire of naturally occurring enzymes repurposed by direct light excitation to catalyze new-to-nature photobiotransformations is currently limited to flavoproteins and keto-reductases. Herein, we shed light on imine reductases (IREDs) that catalyze the remote C(sp³)–C(sp³) bond formation, providing a previously elusive radical hydroalkylation of enamides for accessing chiral amines (45 examples with up to 99% enantiomeric excess). Beyond their natural function in catalyzing two-electron reductive amination reactions, upon direct visible-light excitation or in synergy with a synthetic photoredox catalyst, IREDs are repurposed to tune the non-natural photoinduced single-electron radical processes. By conducting wet mechanistic experiments and computational simulations, we unravel how engineered IREDs direct radical intermediates toward the productive and enantioselective pathway. This work represents a promising paradigm for harnessing nature’s catalysts for new-to-nature asymmetric transformations that remain challenging through traditional chemocatalytic methods.

中文翻译：

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通过基于亚胺还原酶的光酶催化模块化获得手性胺


催化剂的开发是合成创新的基石，最近光酶的发现就是例证。然而，通过直接光激发重新利用以催化新的自然光生物转化的天然存在的酶目前仅限于黄素蛋白和酮还原酶。在此，我们揭示了亚胺还原酶（IRED）催化远程 C(sp ³ )–C(sp ³ ) 键形成，为烯酰胺提供了以前难以捉摸的自由基加氢烷基化反应。获得手性胺（45 个实例，对映体过量高达 99%）。除了催化双电子还原胺化反应的天然功能外，在直接可见光激发或与合成光氧化还原催化剂协同作用下，IRED 还被重新用于调节非天然光诱导的单电子自由基过程。通过进行湿机械实验和计算模拟，我们揭示了工程 IRED 如何将自由基中间体引导至生产和对映选择性途径。这项工作代表了利用自然催化剂进行新的自然不对称转化的有前景的范例，而传统的化学催化方法仍然具有挑战性。