Marrying the advantages of chemical catalysts with the selectivity and evolvability of biocatalysts in chemoenzymatic reactions has recently garnered a lot of attention to access highly sought after chemicals. [[1], [2], [3], [4]] However, challenges remain in finding optimal reaction conditions (buffer, pH, substrate loading) for enzymatic and chemical compatibility. [1,5] C-X (X = C, O, N or S) bond formation and CH functionalization are the cornerstone of recent synthetic methodology and are at the forefront of chemical synthesis. Albeit recent advances using first row transition metals, palladium still remains the metal of choice for C-X bond formation. [6]

Regarding CH activation, monooxygenases such as cytochrome P450 enzymes or unspecific peroxygenases have been attractive biocatalysts with their unique synthetic potential in CH bond oxyfunctionalization of a myriad of organic substrates. [[7], [8], [9], [10], [11]] Several strategies have been put forth to employ monooxygenases in enzymatic cascades as well as in chemoenzymatic reactions, [12] albeit with seldom examples of one-pot chemoenzymatic reactions.

Following the recent work from the Reetz and Hollman groups leveraging Pd catalysis and biocatalysis [13,14] and the development of aqueous Pd catalysis conditions, [[15], [16], [17]] we sought to identify conditions to combine CC bond formation and selective CH activation using the unique regio and stereo oxyfunctionalization of the well-studied cytochrome P450 BM3 enzyme. We report herein the development of a one-pot chemoenzymatic strategy leveraging Pd catalysis and a peroxygenase mutant of the P450 BM3 heme domain to access a series of biarylalkanoic acid derivatives. We rationalized that those compounds could be suitable substrates since this monooxygenase enzyme is known to primarily oxidize long chain fatty acids.

Noteworthy, biaryl alkanoic acids have been a valuable scaffold for non-steroidal anti-inflammatory drugs (NSAIDs), one of the most commonly prescribed pain and inflammation medications [18]. Derivatives bearing various functionalities could have potential therapeutic applications to overcome the challenges and limitations associated with the current drugs on the market [19].

A diverse series of 38 compounds was accessed by Pd-catalyzed cross-coupling reactions using commercially available starting materials and subsequently enzymatically oxyfunctionalized. Furthermore, in order to increase the overall enzymatic product conversion, a substrate engineering approach was employed involving the introduction and subsequent removal of a bulky amino acid such as L-Tryptophan or L-Phenylalanine to the carboxylic acid moiety.