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Copper-catalyzed radical C(sp³)‒N coupling has become a major focus in synthetic catalysis over the past decade. However, achieving this reaction manifold by using enzymes has remained elusive. In this study, we introduce a photobiocatalytic approach for radical benzylic C(sp³)‒N coupling using a copper-substituted nonheme enzyme. Using rhodamine B as a photoredox catalyst, we identified a copper-substituted phenylalanine hydroxylase that facilitates enantioconvergent decarboxylative amination betweenN-hydroxyphthalimide esters and anilines. Directed evolution remodeled the active site, resulting in high enantioselectivities for most substrates. On the basis of molecular modeling and mechanistic studies, we propose that the enzyme accommodates a copper-anilide complex that reacts with a benzylic radical. This study expands the scope of non-natural biocatalytic transition metal catalysis to copper-catalyzed radical coupling. 

Engineered nonheme iron enzymes perform enantioselective radical azidation on aryl N -fluoroamide substrates. 

Previous work has demonstrated that variants of a heme protein, Rhodothermus marinus cytochrome c (Rma cyt c), catalyze abiological carbene boron–hydrogen (B–H) bond insertion with high efficiency and selectivity. Here we investigated this carbon–boron bond-forming chemistry with cyclic, lactone-based carbenes. Using directed evolution, we obtained a Rma cyt c variant BORLAC that shows high selectivity and efficiency for B–H insertion of 5- and 6-membered lactone carbenes (up to 24,500 total turnovers and 97.1:2.9 enantiomeric ratio). The enzyme shows low activity with a 7-membered lactone carbene. Computational studies revealed a highly twisted geometry of the 7-membered lactone carbene intermediate relative to 5- and 6-membered ones. Directed evolution of cytochrome c together with computational characterization of key iron-carbene intermediates has allowed us to expand the scope of enzymatic carbene B–H insertion to produce new lactone-based organoborons. 

Abstract Trifluoromethyl‐substituted cyclopropanes (CF₃‐CPAs) constitute an important class of compounds for drug discovery. While several methods have been developed for synthesis oftrans‐CF₃‐CPAs, stereoselective production of correspondingcis‐diastereomers remains a formidable challenge. We report a biocatalyst for diastereo‐ and enantio‐selective synthesis ofcis‐CF₃‐CPAs with activity on a variety of alkenes. We found that an engineered protoglobin fromAeropyrnum pernix(ApePgb) can catalyze this unusual reaction at preparative scale with low‐to‐excellent yield (6–55 %) and enantioselectivity (17–99 % ee), depending on the substrate. Computational studies revealed that the steric environment in the active site of the protoglobin forced iron‐carbenoid and substrates to adopt a pro‐cisnear‐attack conformation. This work demonstrates the capability of enzyme catalysts to tackle challenging chemistry problems and provides a powerful means to expand the structural diversity of CF₃‐CPAs for drug discovery.