Engineered Enzymes Enable Selective N‐Alkylation of Pyrazoles With Simple Haloalkanes. Issue 10 (21st January 2021)

• Record Type: Journal Article
• Authors: Bengel, Ludwig L.; Aberle, Benjamin; Egler‐Kemmerer, Alexander‐N.; Kienzle, Samuel; Hauer, Bernhard; Hammer, Stephan C.
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 10(2021)
• Page Start: 5554
• Page End: 5560
• Publication Date: 2021-01-21
• Subjects: alkylation -- biocatalysis -- enzyme cofactors -- enzyme engineering -- pyrazoles; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202014239
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Selective alkylation of pyrazoles could solve a challenge in chemistry and streamline synthesis of important molecules. Here we report catalyst‐controlled pyrazole alkylation by a cyclic two‐enzyme cascade. In this enzymatic system, a promiscuous enzyme uses haloalkanes as precursors to generate non‐natural analogs of the common cosubstrate S‐adenosyl‐l ‐methionine. A second engineered enzyme transfers the alkyl group in highly selective C−N bond formations to the pyrazole substrate. The cosubstrate is recycled and only used in catalytic amounts. Key is a computational enzyme‐library design tool that converted a promiscuous methyltransferase into a small enzyme family of pyrazole‐alkylating enzymes in one round of mutagenesis and screening. With this enzymatic system, pyrazole alkylation (methylation, ethylation, propylation) was achieved with unprecedented regioselectivity (>99 %), regiodivergence, and in a first example on preparative scale. Abstract : Biological alkylation is highly selective, yet it depends on complex leaving groups. Now, promiscuous and engineered enzymes achieve selective enzymatic alkylation using simple haloalkanes.