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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 transdisubstituted cyclohexadiene synthons. Here we show that naphthalene epoxides generated by fungal peroxygenases can be subjected to nucleophilic ring opening yielding non-racemic trans-disubstituted cyclohexadiene derivates, which in turn can be used for further chemical transformations. Following the ring-opening reactions, the synthetic possibility of cyclohexadiene derivates also demonstrated by four examples yielding functional compounds. This novel approach may represent a promising shortcut for the synthesis of natural products and APIs.

Versatile bio-derived catalysts have been under dynamic investigation as potential substitutes to conventional chemical catalysts for sustainable biodiesel production. This is because of their unique, low-cost benefits and production processes that are environmentally and economically acceptable. This critical review aspires to present a viable approach to the synthesis of environmentally benign and cost-effective heterogeneous solid-base catalysts from a wide range of biological and industrial waste materials for sustainable biodiesel production. Most of these waste materials include an abundance of metallic minerals like potassium and calcium. The different approaches proposed by researchers to derive highly active catalysts from large-scale waste materials of a re-usable nature are described briefly. Finally, this report extends to present an overview of techno-economic feasibility of biodiesel production, its environmental impacts, commercial aspects of community-based biodiesel production and potential for large-scale expansion.

The oxidation of alkanes into valuable chemical products is a vital reaction in organic synthesis. This reaction, however, is challenging, owing to the inertness of C−H bonds. Transition metal catalysts for C−H functionalization are frequently explored. Despite chemical alternatives, nature has also evolved powerful oxidative enzymes (e. g., methane monooxygenases, cytochrome P450 oxygenases, peroxygenases) that are capable of transforming C−H bonds under very mild conditions, with only the use of molecular oxygen or hydrogen peroxide as electron acceptors. Although progress in alkane oxidation has been reviewed extensively, little attention has been paid to small alkane oxidation. The latter holds great potential for the manufacture of chemicals. This Minireview provides a concise overview of the most relevant enzyme classes capable of small alkanes (C) oxyfunctionalization, describes the essentials of the catalytic mechanisms, and critically outlines the current state-of-the-art in preparative applications.

Bioelectrochemical technologies such as electro-fermentation and microbial CO2 electrosynthesis are emerging interdisciplinary technologies that can produce renewable fuels and chemicals (such as carboxylic acids). The benefits of electrically driven bioprocesses include improved production rate, selectivity, and carbon conversion efficiency. However, the accumulation of products can lead to inhibition of biocatalysts, necessitating further effort in separating products. The recent discovery of a new photoenzyme, capable of converting carboxylic acids to bio-alkanes, has offered an opportunity for system integration, providing a promising approach for simultaneous product separation and valorisation. Combining the strengths of photo/bio/electrochemical catalysis, we discuss an innovative circular cascading system that converts biomass and CO2 to value-added bio-alkanes (CnH2n+2, n = 2 to 5) whilst achieving carbon circularity.

Selective oxyfunctionalizations of inert C−H bonds can be achieved under mild conditions by using peroxygenases. This approach, however, suffers from the poor robustness of these enzymes in the presence of hydrogen peroxide as the stoichiometric oxidant. Herein, we demonstrate that inorganic photocatalysts such as gold–titanium dioxide efficiently provide H2O2 through the methanol‐driven reductive activation of ambient oxygen in amounts that ensure that the enzyme remains highly active and stable. Using this approach, the stereoselective hydroxylation of ethylbenzene to (R)‐1‐phenylethanol was achieved with high enantioselectivity (>98 % ee) and excellent turnover numbers for the biocatalyst (>71 000)., F.H and W.Z. gratefully acknowledge financial support by the European Research Council (ERC Consolidator Grant No. 648026). B.O.B. and J.Z.B. are grateful for financial support from the German Research Foundation (DFG, Grant No. BL 1425/1‐1). We thank Ben Norder (Delft University of Technology) for XRD, Dr. Wiel H. Evers (Delft University of Technology) for TEM, and Prof. Fred Hagen (Delft University of Technology) for EPR measurements.

Aqueous suspensions of lanthanide exchsanged zeolite LTL have been investigated by 1H, 17O NMR, and EPR relaxivity studies. Both the longitudinal and the transverse relaxivity of these Gd3+ loaded materials are strongly pH dependent and therefore, they have great potential as pH responsive contrast agents. For example, LTL-nanocrystals loaded with 3.5 wt % Gd show a dramatic decrease in the longitudinal relaxivity from 32 to 7 s(-1) mM(-1) (7.5 T and 25 degrees C) when going from pH 4 to 9. 1H and O-17 NMR show that this phenomenon can be rationalized by a decrease in proton mobility between the zeolite interior and the exterior due to a change from a fast prototropic exchange to a 3 orders of magnitude slower water exchange mechanism. The same material also has a high transverse relaxivity (98 s(-1) mM(-1) at 7.5 T, 25 degrees C, and pH 5 as measured with the CPMG pulse sequence), which is governed by proton exchange too, while water diffusion plays a minor role. The high relaxivities and pH dependence render Gd-loaded LTL materials promising pH responsive contrast agents. Since the r(2)/r(1) ratio of the designed probe strongly increases with the magnetic field strength, these materials are expected to be applicable for both T-1 and T-2 weighted imaging at low and high fields, respectively.

10 páginas.- 4 figuras.- 2 tablas.- 30 referencias.- Supporting information for this article is given via a link at the end of the document https://onlinelibrary.wiley.com/doi/10.1002/anie.202217372, he hydroxylation of fatty acids is an appealing reaction in synthetic chemistry, although the lack of selective catalysts hampers its industrial implementation. Here, we have engineered a highly regioselective fungal peroxygenase for the w-1 hydroxylation of fatty acids with quenched stepwise over-oxidation. One single mutation near the Phe catalytic tripod narrowed the heme cavity, promoting a dramatic shift toward sub-terminal hydroxylation with a drop in the over-oxidation activity. While crystallographic soaking experiments and molecular dynamic simulations shed light on this unique oxidation pattern, the selective biocatalyst was produced by Pichia pastoris at 0.4 g/L in a fed-batch bioreactor and used in the preparative synthesis of 1.4 g of (w-1)-hydroxytetradecanoic acid with 95% regioselectivity and 83% ee through the (S)-enantiomer.The hydroxylation of fatty acids is an appealing reaction in synthetic chemistry, although the lack of selective catalysts hampers its industrial implementation. Here, we have engineered a highly regioselective fungal peroxygenase for the w-1 hydroxylation of fatty acids with quenched stepwise over-oxidation. One single mutation near the Phe catalytic tripod narrowed the heme cavity, promoting a dramatic shift toward sub-terminal hydroxylation with a drop in the over-oxidation activity. While crystallographic soaking experiments and molecular dynamic simulations shed light on this unique oxidation pattern, the selective biocatalyst was produced by Pichia pastoris at 0.4 g/L in a fed-batch bioreactor and used in the preparative synthesis of 1.4 g of (w-1)-hydroxytetradecanoic acid with 95% regioselectivity and 83% ee through the (S)-enantiomer., This work was supported by the European Union Project grant H2020-BBI-PPP-2015-2-720297-ENZOX2, the I+D+I PID2019-106166RB-I00-OXYWAVE Spanish project funded by the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (AEI)/doi: 10.13039/501100011033/, the PID2020-118968RB-I00 LILI project from the Spanish MCIN/AEI/10.13039/501100011033, the ‘Comunidad de Madrid’ Synergy CAM project Y2018/BIO-4738-EVOCHIMERA-CMand the PIE-CSIC projects PIE-202040E185 and PIE-201580E042. PGS thanks the Ministry of Science, Innovation and Universities (Spain) for her FPI scholarship (BES-2017-080040) and to the Ministry of Science and Innovation for her contract as part of PTQ2020-011037 project funded by MCIN/AEI/10.13039/501100011033 within the NextGenerationEU/PRTR.DGP thanks Juan de la Cierva Incorporación contract Ref nº: IJC2020-043725-I, funded by MCIN / AEI / 10.13039/501100011033, and the EUNextGenerationEU/PRTR program. The authors thank the Synchrotron Radiation Source at Alba (Barcelona, Spain) for assistance with the BL13-XALOC beamline.