Abstract
AbstractA chemical method for the treatment of harmful halogenated compounds that has recently become of interest is the reductive dehalogenation of carbon‐halogen bonds. In the case of a fluorine atom, this process is called hydrodefluorination. While many transition metal‐based approaches now exist to reductively defluorinate aromatic fluoroarenes, the cleavage of C−F bonds in aliphatic compounds is not so well‐developed. Here we propose a biocatalytic approach exploiting a promiscuous activity exhibited by transaminases (TAs). Hence, a series of α‐fluoroketones have been defluorinated with excellent conversions using Chromobacterium violaceum and Arthrobacter sp. TAs under mild conditions and in aqueous medium, using a stoichiometric amount of an amine (e. g. 2‐propylamine) as reagent and formally releasing its oxidized form (e. g. acetone), with ammonia and hydrogen fluoride as by‐products. It is also demonstrated that this process can be performed in a regio‐ or stereoselective fashion.
Highlights
Organic halides are very important compounds due to their high synthetic versatility as reagents, solvents, and intermediates in organic synthesis
The selective hydrodefluorination of α-fluoroketones or aldehydes is a difficult transformation as these carbonyl compounds are highly reactive, and apart from the CÀF bond reduction, the C=O bond can be reduced
Most of the reported catalytic hydrodefluorination protocols rely on the use of transition metal complexes over fluoroarene or alkenyl substrates under harsh reaction conditions
Summary
Organic halides are very important compounds due to their high synthetic versatility as reagents, solvents, and intermediates in organic synthesis On one hand, their occurrence as drug candidates and other biologically active compounds is prominent,[1] but on the other they can present adverse properties from an environmental point of view, as they are slowly degraded. Compounds, as fluorine is currently recognized as one of the most relevant heteroatoms when included in drug molecules This is due to its capacity to modify molecular properties such as lipophilicity, metabolic stability or acidity, among others,[2] and because of its role as a fundamental constituent of pollutants such chlorofluorocarbons (CFCs).[3] The special properties that fluorine confers to organic molecules is to a large extent due to the small size of this atom and the strength of the CÀF bonds. The increasing interest around this halogen has gone in hand with the development of very efficient and selective synthetic pathways to obtain fluorinated compounds.[4]
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