7TNB image
Entry Detail
PDB ID:
7TNB
Keywords:
Title:
Caulobacter segnis arene reductase (CSAR) - WT
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2022-01-20
Release Date:
2022-08-24
Method Details:
Experimental Method:
Resolution:
1.79 Å
R-Value Free:
0.18
R-Value Work:
0.15
Space Group:
C 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:NADH:flavin oxidoreductase/NADH oxidase
Chain IDs:A (auth: AAA)
Chain Length:366
Number of Molecules:1
Biological Source:Caulobacter segnis
Primary Citation
An asymmetric sp 3 -sp 3 cross-electrophile coupling using 'ene'-reductases.
Nature 610 302 307 (2022)
PMID: 35952713 DOI: 10.1038/s41586-022-05167-1

Abstact

The catalytic asymmetric construction of Csp3-Csp3 bonds remains one of the foremost challenges in organic synthesis1. Metal-catalysed cross-electrophile couplings (XECs) have emerged as a powerful tool for C-C bond formation2-5. However, coupling two distinct Csp3 electrophiles with high cross-selectivity and stereoselectivity continues as an unmet challenge. Here we report a highly chemoselective and enantioselective Csp3-Csp3 XEC between alkyl halides and nitroalkanes catalysed by flavin-dependent 'ene'-reductases (EREDs). Photoexcitation of the enzyme-templated charge-transfer complex between an alkyl halide and a flavin cofactor enables the chemoselective reduction of alkyl halide over the thermodynamically favoured nitroalkane partner. The key C-C bond-forming step occurs by means of the reaction of an alkyl radical with an in situ-generated nitronate to form a nitro radical anion that collapses to form nitrite and an alkyl radical. An enzyme-controlled hydrogen atom transfer (HAT) affords high levels of enantioselectivity. This reactivity is unknown in small-molecule catalysis and highlights the potential for enzymes to use new mechanisms to address long-standing synthetic challenges.

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