Structure of the Reductase Domain of a Fungal Carboxylic Acid Reductase and Its Substrate Scope in Thioester and Aldehyde Reduction.

The synthesis of aldehydes from carboxylic acids has long been a challenge in chemistry. In contrast to the harsh chemically driven reduction, enzymes such as carboxylic acid reductases (CARs) are considered appealing biocatalysts for aldehyde production. Although structures of single- and didomains of microbial CARs have been reported, to date no full-length protein structure has been elucidated.

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 (VCPO) generated hypobromite from HO and bromide, which then spontaneously reacted with a broad range of unsaturated carboxylic acids and yielded the corresponding vinyl bromide products. Selectivity issues arising from the (here undesired) addition of water to the intermediate bromonium ion could be solved by reaction medium engineering.

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 be subjected to nucleophilic ring opening, yielding non-racemic trans-disubstituted cyclohexadiene derivates, which in turn can be used for further chemical transformations.

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 enantiomerically pure secondary fatty alcohols.

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.

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

Invited for this month's cover is the group of Prof. Dr. Frank Hollmann at Delft University of Technology in the Netherlands.

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 biocatalyst.

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

An increasing number of biocatalytic oxidation reactions rely on H O as a clean oxidant. The poor robustness of most enzymes towards H O , however, necessitates more efficient systems for in situ H O generation. In analogy to the well-known formate dehydrogenase to promote NADH-dependent reactions, we here propose employing formate oxidase (FOx) to promote H O -dependent enzymatic oxidation reactions.

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 reaction components was demonstrated.

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 these reactions, no "classical" chemical counterpart is known.

Identification of some Bioactive Metabolites in a Fractionated Methanol Extract from Ipomoea aquatica (Aerial Parts) through TLC, HPLC, UPLC-ESI-QTOF-MS and LC-SPE-NMR Fingerprints Analyses.

Introduction: The plant species Ipomoea aquatica contains various bioactive constituents, e.g. phenols and flavonoids, which have several medical uses.

Rapid chemoenzymatic route to glutamate transporter inhibitor l-TFB-TBOA and related amino acids.

The complex amino acid (l-threo)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate (l-TFB-TBOA) and its derivatives are privileged compounds for studying the roles of excitatory amino acid transporters (EAATs) in regulation of glutamatergic neurotransmission, animal behavior, and in the pathogenesis of neurological diseases. The wide-spread use of l-TFB-TBOA stems from its high potency of EAAT inhibition and the lack of off-target binding to glutamate receptors. However, one of the main challenges in the evaluation of l-TFB-TBOA and its derivatives is the laborious synthesis of these compounds in stereoisomerically pure form.

Crystal structure of (4-meth-oxy-phen-yl)[(4-meth-oxy-phen-yl)phospho-nato]dioxidophosphate(1-) 2-amino-6-benzyl-3-eth-oxy-carbon-yl-4,5,6,7-tetra-hydro-thieno[2,3-c]pyridin-6-ium.

The asymmetric unit of the title mol-ecular salt, C17H21N2O2S(+)·C14H15O7P2 (-), comprises two cations and two anions. Each cation features an intra-molecular N-H⋯O hydrogen bond, which closes an S(6) ring; in each case the hydro-pyridine ring adopts a half-chair conformation. In the anions, the dihedral angles between the aromatic rings are 64.

Crystal structure of (5Z)-5-(2-hy-droxy-benzyl-idene)-1,3-thia-zolidine-2,4-dione.

The title compound, C10H7NO3S, crystallizes with four independent mol-ecules in the asymmetric unit with slightly different conformations; the dihedral angles between the six- and five-membered rings are 2.6 (1), 1.09 (9), 8.

Crystal structure of (5Z)-5-(5-bromo-2-hy-droxy-benzyl-idene)-1,3-thia-zolidine-2,4-dione.

In the title compound, C10H6BrNO3S, the dihedral angle between the thia-zolidine ring (r.m.s.

Crystal structure of 2-amino-4-(4-meth-oxy-phen-yl)-4H-benzo[g]chromene-3-carbo-nitrile.

In the title compound, C21H16N2O2, the naphthalene fragment is twisted slightly, as indicated by the dihedral angle of 3.2 (2)° between the two six-membered rings. The pendant 4-meth-oxy-phenyl ring makes a dihedral angle of 86.

Crystal structure of 2-oxo-N'-phenyl-2H-chromene-3-carbohydrazide.

In the title compound, C16H12N2O3, the 2H-chromene moiety is essentially planar, with an r.m.s.

Triclinic and monoclinic polymorphs of meso-(E,E)-1,1'-[1,2-bis(4-chlorophenyl)ethane-1,2-diyl]bis(phenyldiazene): the high-yield synthesis of an unexpected product, concomitant polymorphism and configurational disorder.

Pyrazolidine-3,5-diones and their derivatives exhibit a wide range of biological activities. Seeking to explore the effect of combining a hydrocarbyl ring substituent, as present in sulfinpyrazone (used to treat gout), with a chlorinated aryl ring, as present in muzolimine (a diuretic), we explored the reaction between 1-phenylpyrazolidine-3,5-dione and 4-chlorobenzaldehyde under mildly basic conditions in the expectation of producing the simple condensation product 4-(4-chlorobenzylidene)-1-phenylpyrazolidine-3,5-dione. However, the reaction product proved to be meso-(E,E)-1,1'-[1,2-bis(4-chlorophenyl)ethane-1,2-diyl]bis(phenyldiazene), C26H20Cl2N4, and a tentative mechanism is proposed.

The interplay of solvation, molecular conformation and supramolecular assembly in 1,1'-({[(ethane-1,2-diyl)dioxy](1,2-phenylene)}bis(methanylylidene))bis(thiosemicarbazide) and its N,N-dimethylformamide disolvate.

The wide diversity of applications of thiosemicarbazones and bis(thiosemicarbazones) has seen them used as anticancer and antitubercular agents, and as ligands in metal complexes designed to act as site-specific radiopharmaceuticals. Molecules of 1,1'-({[(ethane-1,2-diyl)dioxy](1,2-phenylene)}bis(methanylylidene))bis(thiosemicarbazide) {alternative name: 2,2'-[ethane-1,2-diylbis(oxy)]dibenzaldehyde bis(thiosemicarbazide)}, C18H20N6O2S2, (I), lie across twofold rotation axes in the space group C2/c, with an O-C-C-O torsion angle of -59.62 (13)° and a trans-planar arrangement of the thiosemicarbazide fragments relative to the adjacent aryl rings.

Crystal structure of 2-amino-7-hy-droxy-4-(4-hy-droxy-phen-yl)-4H-chromene-3-carbo-nitrile.

In the title compound, C16H12N2O3, the chromene ring system is nearly planar [maximum deviation from the mean plane = 0.057 (1) Å], and is almost perpendicular to the benzene ring, with a dihedral angle of 85.29 (5)°.

Crystal structure of 3-amino-1-(4-hy-droxy-phen-yl)-1H-benzo[f]chromene-2-carbo-nitrile.

In the title compound, C20H14N2O2, the hy-droxy-benzene ring is almost perpendicular to the mean plane of the naphthalene ring system, making a dihedral angle of 85.56 (4)°. The 4H-pyran ring fused with the naphthalene ring system has a flattened boat conformation.

Crystal structure of [(E)-({2-[3-(2-{(1E)-[(carbamo-thioyl-amino)-imino]-meth-yl}phen-oxy)prop-oxy]phen-yl}methyl-idene)amino]-thio-urea with an unknown solvate.

The title mol-ecule, C19H22N6O2S2, has crystallographically imposed C 2 symmetry, with the central C atom lying on the rotation axis. The O-C-C-C torsion angle for the central chain is -59.22 (16)° and the dihedral angle between the planes of the benzene rings is 75.

Crystal structure of ethyl (4R)-2-amino-7-hy-droxy-4-phenyl-4H-chromene-3-carboxyl-ate.

In the title compound, C18H17NO4, the dihedral angle between the phenyl ring and the fused six-membered ring is 77.65 (4)°. The conformation of the mol-ecule is determined in part by an intra-molecular N-H⋯O hydrogen bond between the amino H atom and the carbonyl O atom, forming an S(6) motif.

Crystal structure of 2-amino-4-phenyl-4H-benzo[h]chromene-3-carbo-nitrile.

In the title compound, C20H14N2O, the plane of the phenyl ring is almost normal to that of the naphthalene ring system, forming a dihedral angle of 83.15 (8)°. The 4H-pyran ring fused with the naphthalene ring system has a flattened boat conformation.

Crystal structure of 3-amino-1-(4-chloro-phen-yl)-1H-benzo[f]chromene-2-carbo-nitrile.

In the title compound, C20H13ClN2O, the chloro-benzene ring is almost perpendicular to the mean plane of the naphthalene ring system, making a dihedral angle of 81.26 (8)°. The 4H-pyran ring fused with the naphthalene ring system has a flattened boat conformation.