Enantioselective Synthesis of α-Trifluoromethyl Amines via Biocatalytic N–H Bond Insertion with Acceptor-Acceptor Carbene Donors

Abstract

The biocatalytic toolbox has recently been expanded to include enzyme-catalyzed carbene transfer reactions not occurring in Nature. Herein, we report the development of a biocatalytic strategy for the synthesis of enantioenriched α-trifluoromethyl amines through an asymmetric N–H carbene insertion reaction catalyzed by engineered variants of cytochrome c 552 from Hydrogenobacter thermophilus . Using a combination of protein and substrate engineering, this metalloprotein scaffold was redesigned to enable the synthesis of chiral α-trifluoromethyl amino esters with up to >99% yield and 95:5 er using benzyl 2-diazotrifluoropropanoate as the carbene donor. When the diazo reagent was varied, the enantioselectivity of the enzyme could be inverted to produce the opposite enantiomers of these products with up to 99.5:0.5 er. This methodology is applicable to a broad range of aryl amine substrates, and it can be leveraged to obtain chemoenzymatic access to enantioenriched β-trifluoromethyl-β-amino alcohols and halides. Computational analyses provide insights into the interplay of protein- and reagent-mediated control on the enantioselectivity of this reaction. This work introduces the first example of a biocatalytic N–H carbenoid insertion with an acceptor–acceptor carbene donor, and it offers a biocatalytic solution for the enantioselective synthesis of α-trifluoromethylated amines as valuable synthons for medicinal chemistry and the synthesis of bioactive molecules.

Copper‐Catalyzed Boroaminomethylation of Olefins to γ‐Boryl Amines with CO as C1 Source

“…Unambiguously, the carbene intermediate was utilized to generate α ‐boryl vinyl esters, cyclopropane motifs, and ketenes by α −C−H insertion, [32] β −C−H insertion, [33] and CO insertion, [34] respectively (Figure c). On the other hand, carbene insertion into the nitrogen‐hydrogen (N−H) bond has been well developed [35–38] . Therefore, we speculate that the application of N−H insertion of the amine to the carbene intermediate would provide an opportunity to achieve straightforward γ ‐boryl amines production.…”

Synthesis of Pincer type carbene and their Ag(I)-NHC complexes, and their Antimicrobial activities

“…Cyclic diamine carbenes allow the provision of σ-donor-π-receiver complexes [1,2] that have powerful chemical stability in terms of water and oxygen tolerance accord-ing to complexes relying on phosphine ligands and they have generally lower toxicity [3]. After sporadic studies, concerning the cellular toxicity of these kind NHC compounds, the cytotoxic effects [4] and mechanisms of action against bacteria it was identified [5,6].…”

Co-Crystal Structure-Guided Optimization of Dual-Functional Small Molecules for Improving the Peroxygenase Activity of Cytochrome P450BM3

“…Cytochrome P450 enzymes (P450s) are a superfamily of heme proteins involved in drug metabolism, xenobiotic detoxification, and steroid biosynthesis [ 1 , 2 ]. P450s are promising biocatalysts for organic synthesis, drug discovery, and bioremediation because of their versatile catalytic oxyfunctionalizations of a variety of substrates [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. However, one of the limitations of applying P450s as in vitro biocatalysts is that most P450s require reduced nicotinamide cofactors NAD(P)H and a complex system of electron transport partners (redox partners) to activate molecular oxygen for the formation of active species.…”