https://pure.rug.nl/ws/files/49577911/Bacterial_enzymes_involved_in_lignin_degradation.pdf

Bacterial enzymes involved in lignin degradation.

Exploiting and engineering hemoproteins for abiological carbene and nitrene transfer reactions.

This Review is aimed at synthetic organic chemists who may be familiar with organometallic catalysis but have no experience with biocatalysis, and seeks to provide an answer to the perennial question: if it is so attractive, why wasn't it extensively used in the past? The development of biocatalysis in industrial organic synthesis is traced from the middle of the last century. Advances in molecular biology in the last two decades, in particular genome sequencing, gene synthesis and directed evolution of proteins, have enabled remarkable improvements in scope and substantially reduced biocatalyst development times and cost contributions. Additionally, improvements in biocatalyst recovery and reuse have been facilitated by developments in enzyme immobilization technologies. Biocatalysis has become eminently competitive with chemocatalysis and the biocatalytic production of important pharmaceutical intermediates, such as enantiopure alcohols and amines, has become mainstream organic synthesis. The synthetic space of biocatalysis has significantly expanded and is currently being extended even further to include new-to-nature biocatalytic reactions.

Broadening the Scope of Biocatalysis in Sustainable Organic Synthesis

We report an efficient strategy for the asymmetric synthesis of trifluoromethyl-substituted cyclopropanes by means of myoglobin-catalyzed olefin cyclopropanation reactions in the presence of 2-diazo-1,1,1-trifluoroethane (CF3CHN2) as the carbene donor. These transformations were realized using a two-compartment setup in which ex situ generated gaseous CF3CHN2 is processed by engineered myoglobin catalysts expressed in bacterial cells. This approach was successfully applied to afford a variety of trans-1-trifluoromethyl-2-arylcyclopropanes in high yields (61–99%) and excellent diastereo- and enantioselectivity (97–99.9% de and ee). Furthermore, mirror-image forms of these products could be obtained using myoglobin variants featuring stereodivergent selectivity. These reactions provide a convenient and effective biocatalytic route to the stereoselective synthesis of key fluorinated building blocks of high value for medicinal chemistry and drug discovery. This work expands the range of carbene-mediated trans...

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Highly Diastereo- and Enantioselective Synthesis of Trifluoromethyl-Substituted Cyclopropanes via Myoglobin-Catalyzed Transfer of Trifluoromethylcarbene.

In industries and academic laboratories, several late transition metal-catalyzed prerequisite reactions are widely performed during single and multistep synthesis. However, besides the desired products, these reactions lead to the generation of numerous chemical waste materials, by-products, hazardous gases, and other poisonous materials, which are discarded in the environment. This is partly responsible for the creation of global warming, resulting in climate adversities. Thus, the development of environmentally benign, cheap, easily accessible, and earth-abundant metal catalysts is desirable to minimize these issues. Certainly, iron is one of the most important metals belonging to this family. The field of iron catalysis has been explored in the last two-three decades out of its rich chemistry depending on its oxidation states and ligand cooperation. Moreover, this field has been enriched by the promising development of iron-catalyzed reactions namely, C–H bond activation, including organometallic C–H activation and C–H functionalization via outer-sphere pathway, cross-dehydrogenative couplings, insertion reactions, cross-coupling reactions, hydrogenations including hydrogen borrowing reactions, hydrosilylation and hydroboration, addition reactions and substitution reactions. Thus, herein an inclusive overview of these reaction have been well documented.

Organic synthesis with the most abundant transition metal–iron: from rust to multitasking catalysts

The base metal complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the rearrangement of vinyl and arylcyclopropanes both under thermal or photochemical conditions to give the corresponding vinyl or aryldihydrofurans in good to excellent yields. Under photochemical conditions the reaction is performed at room temperature. Spectroscopic investigations show that the metal carbonyl catalyst is not decarbonylated. The best performance was observed at a wavelength of 415 nm. icMRCI+Q analysis of the excited singlet and triplet states of the [Fe(CO)3(NO)] anion was performed and used to calculate the vertical excitation energies which are in good agreement with the experimental data. CASSCF analysis indicates that the Fe center in all excited states of the ferrate becomes more electrophilic while adopting a distorted tetrahedral configuration. Both aspects have a positive synergistic effect on the formation of the initial π-complex with the incoming organic substrate.

/pdf/non-decarbonylative-photochemical-versus-thermal-activation-2bhewz4c91.pdf

Non-decarbonylative photochemical versus thermal activation of Bu4N[Fe(CO)3(NO)] – the Fe-catalyzed Cloke–Wilson rearrangement of vinyl and arylcyclopropanes

The Wittig-type carbonyl olefination reaction has no biocatalytic equivalent. To build complex molecular scaffolds, however, C−C bond-forming reactions are pivotal for biobased economy and synthetic biology. The heme-containing E. coli protein YfeX was found to catalyze carbonyl olefination by reaction of benzaldehyde with ethyl diazoacetate under aerobic conditions in the absence of a triphenylphosphine oxophile. The reaction was performed in whole cells and showed a product formation of 440 mg L−1 in 1 h. It was, moreover, shown that the reaction could be performed under Wittig-analogue conditions in the presence of triphenylphosphine or triphenylarsine.

Enzyme‐Catalyzed Carbonyl Olefination by the E. coli Protein YfeX in the Absence of Phosphines

Hydroboration of internal alkynes catalyzed by FeH(CO)(NO)(PPh3)2: a case of boron-source controlled regioselectivity

Tetraaryladamantanes have proven useful as chaperones for the co-crystallization of small molecules that do not readily crystallize by themselves. The co-crystals are often useful for structure elucidation. Usually, the small molecules are encapsulated in the crystal lattice of the aryladamantane that forms during rapid thermal crystallization. Thus far, co-crystallization has been limited to liquids as guest molecules. Here we report the co-crystal structures of phenol, which is solid at room temperature, with both 1,3,5,7-tetrakis(2,4-dimethoxyphenyl)adamantane (TDA) and 1,3,5,7-tetrakis(2,4-diethoxyphenyl)adamantane (TEO). The co-crystals were obtained from solutions in dichloromethane by slow evaporation or diffusion. The implications for generating other co-crystals of two solids are briefly discussed.

https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-17-103.pdf

Co-crystallization of an organic solid and a tetraaryladamantane at room temperature.

The Fe-catalyzed Cloke—Wilson rearrangement of vinylcyclopropanes (I), (IV), and (VI) under photochemical conditions proceeds in a shorter time and with similar or higher yields compared to the reaction under thermal conditions.

Non-decarbonylative Photochemical versus Thermal Activation of Bu4N[Fe(CO)3(NO)] — The Fe-Catalyzed Cloke—Wilson Rearrangement of Vinyl and Arylcyclopropanes.

Fabian Rami

Papers

Non-decarbonylative photochemical versus thermal activation of Bu4N[Fe(CO)3(NO)] – the Fe-catalyzed Cloke–Wilson rearrangement of vinyl and arylcyclopropanes

Enzyme‐Catalyzed Carbonyl Olefination by the E. coli Protein YfeX in the Absence of Phosphines

Hydroboration of internal alkynes catalyzed by FeH(CO)(NO)(PPh3)2: a case of boron-source controlled regioselectivity

Co-crystallization of an organic solid and a tetraaryladamantane at room temperature.

Non-decarbonylative Photochemical versus Thermal Activation of Bu4N[Fe(CO)3(NO)] — The Fe-Catalyzed Cloke—Wilson Rearrangement of Vinyl and Arylcyclopropanes.