Unspecific Peroxygenases for the Enzymatic Removal of Alkyl Protecting Groups in Organic Synthesis

Abstract

Selective protection and deprotection of hydroxyl groups is pivotal in multistep organic synthesis to circumvent undesired side reactions. Alkyl ethers are highly stable and atomeconomic protecting groups (PGs), but demand harsh and hazardous conditions for removal, limiting their utility. Consequently, there is a high demand for biocatalysts as milder, selective, and scalable alternatives, which can be met by a class of heme-thiolate enzymes: unspecific peroxygenases (UPOs). Herein, we report the identification of UPO23 in a commercial enzyme panel as a robust iocatalyst for O-dealkylation reactions. UPO23 exhibited a broad substrate scope and efficiently removed methyl, ethyl, propyl, or allyl groups from protected primary, secondary, tertiary, and benzylic alcohols under ambient conditions.Mechanistic investigations revealed dual reaction pathways for UPO23, hydroxylating either the α-carbon of the alkyl chain of the PG or the substrate scaffold, explaining the formation of deprotected target alcohols as well as further oxidized products. Optimized reaction conditions reduced reaction times from 4 h to 15 min for methyl protected key substrates. Preparative scale reactions with protected benzyl ethers yielded up to 92% of the isolated alcohol products. These findings highlight the versatility of UPO23 and offer scalable, environmentally benign, and enzyme-based deprotection strategies for multistep organic synthesis.