Related Experiment Video
Updated: Feb 28, 2026

Preparation of Enantiopure Non-Activated Aziridines and Synthesis of Biemamide B, D, and epiallo-Isomuscarine
Published on: June 13, 2022
Reprogramming Imine Reductases for Enantioselective Reduction of Electron-Rich Enamides
Xiao-Qi Liu1,2, Ru Li1,2, Jun-Liang Chen1,2
1Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, Department of Biopharmaceutics, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
Researchers reprogrammed imine reductases (IREDs) to enantioselectively reduce enamides, creating chiral amines. This breakthrough expands biocatalyst capabilities for synthesizing valuable amine compounds.
Area of Science:
- Biocatalysis
- Enzyme Engineering
Background:
- Imine reductases (IREDs) are biocatalysts for chiral amine synthesis via imine reduction.
- Direct reduction of electron-rich alkenes by IREDs is biologically unprecedented and challenging.
Purpose of the Study:
- To reprogram an IRED for the enantioselective reduction of enamides.
- To expand the substrate scope and catalytic versatility of IREDs.
Main Methods:
- Directed evolution of an IRED from *Sinorhizobium* (SinIRED).
- Enzymatic assays to evaluate the activity and selectivity of engineered variants.
- Mechanistic studies to elucidate the reaction pathway.
Main Results:
- Developed the SinIRED-V5 variant with enhanced activity towards enamides.
- Achieved high yields (up to 97%) and excellent enantioselectivity (>99:1 e.r.) for diverse protected chiral amines.
- Identified a novel synergistic mechanism involving enamine-imine tautomerization and NADPH-dependent hydride transfer.
Conclusions:
- Demonstrated the first successful IRED-catalyzed reduction of electron-rich enamides.
- Expanded the catalytic repertoire of IREDs beyond imine reduction.
- Provided a new biocatalytic route for synthesizing valuable chiral amines from enamides.
Related Concept Videos
Preparation of Amines: Reductive Amination of Aldehydes and Ketones
Amides to Amines: LiAlH4 Reduction
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
Preparation of Amines: Reduction of Oximes and Nitro Compounds
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Nitriles to Amines: LiAlH4 Reduction
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
Preparation of Amines: Reduction of Amides and Nitriles
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...

![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)