Hot Paper in Angewandte Chemie International Edition: Engineered enzymes enable selective N-alkylation of pyrazoles with simple haloalkanes

January 22, 2021

Paper by Ludwig L. Bengel, Benjamin Aberle, Alexander-N. Egler-Kemmerer, Samuel Kienzle, Bernhard Hauer and Stephan C. Hammer

Selective alkylation of pyrazoles could solve a challenge in chemistry and streamline synthesis of important molecules. A pyrazole-methylating enzyme family that transfers alkyl groups in catalyst-controlled highly selective C-N bond formations to the pyrazole substrate was created using a computational enzyme library design tool. A second, promiscuous enzyme generates non-natural-analogues of the common cofactor S-adenosyl-l-methionine utilizing simple haloalkanes as precursors. These enzymes were combined in a bienzymatic cascade where the cofactor is recycled and only used in catalytic amounts. With this enzymatic system, selective pyrazole alkylation (methylation, ethylation and propylation) was achieved with unprecedented regioselectivities (>99%), regiodivergence and in a first example on preparative scale.

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