A solvent-free synthesis of (thio)ester derivatives using FeCl₃ as a heterogeneous catalyst

A simple, solvent-free method for the synthesis of (thio)esters from simple acid chlorides at room temperature is reported. Simple FeCl₃ (5 mol%) enables facile, near complete conversion of equimolar starting materials in high selectivity. Recycling of the catalyst has been demonstrated.

Chemoenzymatic Hunsdiecker-Type Decarboxylative Bromination of Cinnamic Acids

In this contribution, we report chemoenzymatic bromodecarboxylation (Hunsdiecker-type) of α,ß-unsaturated carboxylic acids. The extraordinarily robust chloroperoxidase from Curvularia inaequalis (CiVCPO) generated hypobromite from H2O2 and bromide, which then spontaneously reacted with a broad range of unsaturated carboxylic acids and yielded...

Biocatalytic Aromaticity-Breaking Epoxidation of Naphthalene and Nucleophilic Ring-Opening Reactions

Aromatic hydroxylation reactions catalyzed by heme-thiolate enzymes proceed via an epoxide intermediate. These aromatic epoxides could be valuable building blocks for organic synthesis giving access to a range of chiral trans-disubstituted cyclohexadiene synthons. Here, we show that naphthalene epoxides generated by fungal peroxygenases can...

Chemoenzymatic Halocyclization of 4-Pentenoic Acid at Preparative Scale

The scale-up of chemoenzymatic bromolactonization to 100 g scale is presented, together with an identification of current limitations. The preparative-scale reaction also allowed for meaningful mass balances identifying current bottlenecks of the chemoenzymatic reaction.

Photobiocatalytic synthesis of chiral secondary fatty alcohols from renewable unsaturated fatty acids

En route to a bio-based chemical industry, the conversion of fatty acids into building blocks is of particular interest. Enzymatic routes, occurring under mild conditions and excelling by intrinsic selectivity, are particularly attractive. Here we report photoenzymatic cascade reactions to transform unsaturated fatty acids into...

Efficient Aerobic Oxidation of trans-2-Hexen-1-ol using the Aryl Alcohol Oxidase from Pleurotus eryngii

The selective oxidation of trans-2-hexen-1-ol to the corresponding aldehyde using a recombinant aryl alcohol oxidase from Pleurotus eryngii (PeAAOx) is reported. Especially using the two liquid phase system to overcome solubility and product inhibition issues enabled to achieve more than 2.200.000 catalytic turnovers for the production enzyme...

Chemoenzymatic Halocyclization of γ,δ-Unsaturated Carboxylic Acids and Alcohols

A chemoenzymatic method for the halocyclization of unsaturated alcohols and acids by using the robust V-dependent chloroperoxidase from Curvularia inaequalis (CiVCPO) as catalyst has been developed for the in situ generation of hypohalites. A broad range of halolactones and cyclic haloethers are formed with excellent performance of the...

Formate Oxidase (FOx) from Aspergillus oryzae: One Catalyst Enables Diverse H ₂ O ₂ -Dependent Biocatalytic Oxidation Reactions

An increasing number of biocatalytic oxidation reactions rely on H ₂ O ₂ as a clean oxidant. The poor robustness of most enzymes towards H ₂ O ₂ , however, necessitates more efficient systems for in situ H ₂ O ₂ generation. In analogy to the well-known formate dehydrogenase to...

Deazaflavins as photocatalysts for the direct reductive regeneration of flavoenzymes

Deazaflavins are potentially useful redox mediators for the direct, nicotinamide-independent regeneration of oxidoreductases. Especially the O₂-stability of their reduced forms have attracted significant interest for the regeneration of monooxygenases. In this contribution we further investigate the photochemical properties of...

Selective Synthesis of the Human Drug Metabolite 5′-Hydroxypropranolol by an Evolved Self-Sufficient Peroxygenase

Propranolol is a widely used beta-blocker that is metabolized by human liver P450 monooxygenases into equipotent hydroxylated human drug metabolites (HDMs). It is paramount for the pharmaceutical industry to evaluate the toxicity and activity of these metabolites, but unfortunately, their synthesis has hitherto involved the use of severe...

Biocatalytic Oxidation Reactions: A Chemist's Perspective

Oxidation chemistry using enzymes is approaching maturity and practical applicability in organic synthesis. Oxidoreductases (enzymes catalysing redox reactions) enable chemists to perform highly selective and efficient transformations ranging from simple alcohol oxidations to stereoselective halogenations of non‐activated C−H bonds. For many of...

A Photoenzymatic NADH Regeneration System

A photoenzymatic NADH regeneration system was established. The combination of deazariboflavin as a photocatalyst with putidaredoxin reductase enabled the selective reduction of NAD⁺ into the enzyme-active 1,4-NADH to promote an alcohol dehydrogenase catalysed stereospecific reduction reaction. The catalytic turnover of all the...

Alcohol Dehydrogenases Catalyze the Reduction of Thioesters

Alcohol dehydrogenases are well-established catalysts for various reduction reactions. However, the reduction of carboxylic acid derivatives has not yet been reported with these enzymes. In this contribution, we demonstrated that carboxylic acid thioesters could be readily reduced by a range of alcohol dehydrogenases, albeit at significantly...

A Biocatalytic Aza-Achmatowicz Reaction

A catalytic, enzyme-initiated (aza-) Achmatowicz reaction is presented. The involvement of a robust vanadium-dependent peroxidase from Curvularia inaequalis allows the simple use of H₂O₂ and catalytic amounts of bromide.