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The mechanism and enantiochemistry of non-C2-symmetric BINOLate titanium (1 : 1) catalyzed cyanation of aldehydes have been investigated using density functional theory (DFT). Calculation results suggest that the mononuclear titanium–BINOLate complex might be the dominant catalyst structure of this cyanation reaction. Using benzaldehyde as the substrate, the cyanation reaction could be completed via the bifunctional LALB mechanism or the Ti-HCN mechanism. For the bifunctional LALB mechanism, HCN needs to be isomerized to HNC under the catalysis of the imine N atom of imidazole firstly, then it attacks the carbonyl C atom to form the C–C bond, followed by a hydrogen transfer step to yield product cyanohydrins. For the Ti-HCN mechanism, following the formation of catalyst–HCN complexes is a decomposition step of HCN, and then the decomposed HCN directs the aldehyde to generate the final product via a concerted transition state. Computational results demonstrate that both isomerization and decomposition of HCN are predicted as the rate-determining steps of two reaction mechanisms. The enantioselectivity of the title reaction is mainly controlled by the energetic performance of the C–C bond-forming transition states, which is influenced greatly by the solvent effects. The calculation results show that the (S)-configuration product would be the predominant product in CH2Cl2, which is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Asymmetric cyanosilylation serves as an important tool to convert easily available ketones into cyanohydrins of diverse reactivity. Whereas a large library of organocatalysts and transition-metal catalysts have been identified for monoketones, cyanosilylation of more-complex substrates, particularly those giving enantioenriched vicinal stereocenters, is underexplored in comparison. Here, a pair of recently published kinetic resolution and desymmetrization methods are highlighted for their success in constructing complex vicinal stereocenters by cyanosilylation using tailored aluminum and magnesium catalysts, respectively. 1 Introduction 2 Kinetic Resolution of α-Branched Ketones 3 Desymmetrization of 1,3-Diketones 4 Conclusion [ABSTRACT FROM AUTHOR]

The release of cyanide from cyanogenic precursors is the central core of the plant defences based on the cyanogenesis process. Although cyanide is formed as a coproduct of some metabolic routes, its production is mostly due to the degradation of cyanohydrins originating from cyanogenic glycosides in cyanogenic plants and the 4-OH-ICN route in Brassicaceae. Cyanohydrins are then hydrolysed in a reversible reaction generating cyanide, being both, cyanohydrins and cyanide, toxic compounds with potential defensive properties against pests and pathogens. Based on the production of cyanogenic-derived molecules in response to the damage caused by herbivore infestation, in this review, we compile the actual knowledge of plant cyanogenic events in the plant–pest context. Besides the defensive potential, the mode of action, and the targets of the cyanogenic compounds to combat phytophagous insects and acari, special attention has been paid to arthropod responses and the strategies to overcome the impact of cyanogenesis. Physiological and behavioural adaptations, as well as cyanide detoxification by β-cyanoalanine synthases, rhodaneses, and cyanases are common ways of phytophagous arthropods defences against the cyanide produced by plants. Much experimental work is needed to further understand the complexities and specificities of the defence–counter-defence system to be applied in breeding programs. [ABSTRACT FROM AUTHOR]

Hydroxynitrile lyases (HNLs) primarily catalyze the stereoselective synthesis of cyanohydrins, but some of them also carry out asymmetric nitroaldol synthesis (Henry reaction). By virtue of the importance of asymmetric C−C bond formation, and the wide application of chiral cyanohydrins and β‐nitroalcohols, HNLs have gained significance in organic synthesis. Over the years new HNLs have been discovered and their synthetic scope are evaluated. Engineering of HNLs has contributed towards increasing not only the catalytic toolbox but also broad substrate selectivity, stereoselectivity, enzyme stability, and application of the enzymes for different transformations other than the conventional ones. This review describes the recent discoveries of diverse hydroxynitrile lyases (HNLs) and the developments to date since 2016, with respect to their biocatalytic applications in the asymmetric synthesis using both natural and promiscuous reactions. [ABSTRACT FROM AUTHOR]

The HNL from the defatted meal of the seeds of Pouteria sapota (PsHNL) was extracted with water, and the aqueous extract was immobilized over celite or lyophilized and used as semi-purified PsHNL. The aqueous extract was mixed with celite, ratios 1:1, 1:2 and 1:4, and lyophilized. The immobilized PsHNLdir-celite catalysed the addition of HCN to 1b in buffer saturated-DIPE (microaqueous system) with high enantioselectivity in the first cycle but diminished in the next two cycles, best results were obtained with the ratio 1:4. The reaction with PsHNLdir-celite in biphasic medium (5% citrates buffer) improved the conversion compared with the microaqueous system, but it was still lower to that obtained with the PsHNL. Other way of immobilization studied was the precipitation of the enzyme with acetone and immobilization on celite, the PsHNLpp-celite catalysed the enantioselective addition of HCN to 2-fluoro (1a), 2-chloro (1b), 2-bromo (1c), 2-methyl (1d) and 2-nitro (1e) benzaldehydes, in the biphasic medium (1:4 ratio, 5% citrates buffer). The enantiomeric excess (ee) of (R)-2a, (R)-2b, (R)-2c and (R)-2d were >98% and remained during the three cycles. The ee of 2-nitromandelonitrile was 82% and was raised to 95% in the third cycle. Compared with the PsHNL, the conversion of 1a and 1b diminished 6% and 40%, respectively, after third cycle; for 2c, conversion was almost 10% higher in the first two cycles and diminished 19% in the third; for 2d and 2e the conversion was between 18–13% and 31–18% higher, respectively. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed cross-coupling of the lithium anion of aryl tert -butyldimethylsilyl-protected cyanohydrins with aryl bromides followed by in situ deprotection with fluoride ion provides a convenient and versatile approach to biaryl ketones. This protocol represents the first example of a palladium-catalyzed arylation of a cyanohydrin, which functions as an acyl anion equivalent. Hence, in contrast to classical cross-coupling reactions, the pronucleophile component is incorporated in the product to permit further functionalization. We then highlight the synthetic utility of the new method with applications to bioactive biaryl ketones and the construction of a triaryl diketone that has been used to prepare an extended tetrathiafulvalene. [ABSTRACT FROM AUTHOR]

Two well‐defined novel binuclear cobalt (II) [Co(H2L1)]2 and [Co(H2L2)]2 compounds are presented. Binuclear cobalt (II) complexes (1–2) containing 1,1′‐binaphthyl derived tetradentate (N2O2) donor ligands H2L1 and H2L2, namely 3,3‐bis[((2,6‐diisopropylphenyl)imino)methyl]‐[1,1′‐binaphthalene‐2,2′‐dioxodicobalt(II) and 3,3′‐bis‐[((2,6‐diethyl‐phenyl)imino)‐ethyl]‐[1,1′]‐binaphtyl‐2,2′‐dioxocobalt(II) complexes were synthesized and isolated for the first time. Various spectroscopic techniques, including UV‐visible spectra, magnetic susceptibility, cyclic voltammetry, elemental analysis, mass spectrometry, and single‐crystal X‐ray diffraction were used to structurally characterize these binuclear cobalt(II) complexes. The binuclear cobalt (II) [Co(H2L1)]2 and [Co(H2L2)]2 complexes (1–2) demonstrated excellent catalytic activity in the cyanosilylation reaction of various aryl aldehydes to value‐added cyanohydrins at room temperature under solvent‐free conditions. [ABSTRACT FROM AUTHOR]

Chiral phosphoric acids (CPAs) and their salts are the privileged catalysts in a plethora of asymmetric transformations. All of the scaffolds of efficient CPAs rely on C2‐symmetry and axial chirality, while the only examples of punctually chiral CPAs are TADDOL derivatives. Herein, we present the design and the synthesis of C2‐symmetric cycloglycerophosphates (cGPAs) and their application throughout the addition of trimethylsilyl cyanide (TMSCN) to aldehydes and ketones, to obtain the corresponding cyanohydrins in yields between 77 and 99% and ee between 84.2 and 99.5% (27 examples). A DFT computational model is moreover performed to rationalize the reaction mechanism and its stereochemical outcome. [ABSTRACT FROM AUTHOR]

Plants and phytophagous arthropods have coevolved in a long battle for survival. Plants respond to phytophagous feeders by producing a battery of antiherbivore chemical defences, while herbivores try to adapt to their hosts by attenuating the toxic effect of the defence compounds. Cyanogenic glucosides are a widespread group of defence chemicals that come from cyanogenic plants. Among the non-cyanogenic ones, the Brassicaceae family has evolved an alternative cyanogenic pathway to produce cyanohydrin as a way to expand defences. When a plant tissue is disrupted by an herbivore attack, cyanogenic substrates are brought into contact with degrading enzymes that cause the release of toxic hydrogen cyanide and derived carbonyl compounds. In this review, we focus our attention on the plant metabolic pathways linked to cyanogenesis to generate cyanide. It also highlights the role of cyanogenesis as a key defence mechanism of plants to fight against herbivore arthropods, and we discuss the potential of cyanogenesis-derived molecules as alternative strategies for pest control. [ABSTRACT FROM AUTHOR]

Cyanide ion was derivatized with o -phthalaldehyde and 3-mercaptopropionic acid for high-performance liquid chromatography-diode array detector analysis. The structure was elucidated using nuclear magnetic resonance spectroscopy and ultra-high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry. Method validation was conducted for three distillation methods to analyze cyanogenic glycosides, cyanohydrins, and free cyanide in fruit syrup. Acid-aided distillation only detected free cyanide, while direct distillation detected both free cyanide and cyanohydrins, and enzyme-aided distillation reflected all three types. These approaches were applied to stone fruit syrups in South Korean markets and households. Among tested, maesil (Prunus mume) syrup contained the highest amount of total cyanide, reaching a maximum of 21.9 mg/kg (cyanide ion equivalent), compared to other syrups. Investigation of cyanide composition changes during maesil syrup production revealed that free cyanide occupies the lowest proportion. Cyanogenic glycosides degraded gradually during aging, while cyanohydrins remained the majority after 12 months aging. • Development and structural identification of a novel cyanide derivative. • Validating 3 ways to analyze cyanogenic glycosides, cyanohydrins and free cyanide. • The highest total cyanide level in maesil syrup compared with other tested syrups. • Elucidation of cyanide composition changes during maesil syrup production. [ABSTRACT FROM AUTHOR]

Crystallization‐Induced Diastereomer Transformation (CIDT) of α‐bromo‐α'‐(R)‐sulfinylketones is reported. The utility of these 1,2‐difunctionalized synthons is convincingly demonstrated by their facile conversion into cyanohydrins and bromohydrins. Furthermore, bromohydrins can be converted into complex arrangements of functionality and stereochemistry through SN2‐like inter and intramolecular transformations. [ABSTRACT FROM AUTHOR]

An electrochemical method for the azidocyanation of alkenes via 1,4-nitrile migration has been developed. This organic oxidant free method is applicable across various alkene containing cyanohydrins, and provides access to a broad range of synthetically useful 1,2-azidonitriles (28 examples). This methodology was extended to an electrochemical alkene sulfonylcyanation procedure, as well as to access a trifunctionalized hexanenitrile from a malononitrile starting material. The orthogonal derivatization of the products was also demonstrated through chemoselective transformations. [ABSTRACT FROM AUTHOR]

Herein we describe the reaction of cyanohydrins with α‐functionalized sulfonyl chlorides and discuss the reactivity of target α‐functionalized β‐enamino γ‐sultones. Depending on electron‐withdrawing activity of α‐functionality of given sulfonyl chlorides the reaction with cyanohydrins either accomplished in one‐pot manner (tandem sulfonylation–CSIC reaction) affording β‐enamino γ‐sultones (α‐functionality=CO2Me, CN, p‐C6H4‐CO2Me) or resulted in sulfonylated cyanohydrins, which can be converted into target β‐enamino γ‐sultones through the t‐BuOK‐mediated CSIC reaction (α‐functionality=Ph). The nature of α‐functionality drastically affects the reactivity of α‐functionalized β‐enamino γ‐sultones. Specifically, α‐CO2Me and α‐CN β‐enamino γ‐sultones are less reactive toward electrophiles and tolerate the nucleophiles. This is the consequence of high degree of conjugation between amino group and EWG within the sultone framework. At the same time, α‐aryl β‐enamino γ‐sultones possess significantly lower degree of conjugation (due to steric hindrance between aryl core and sultone framework) and therefore retain reactivity of the enamine fragment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Selenium-containing cyanohydrin acetates were crucial intermediates in synthesizing polyfunctionalized selenides. • Se-containing diesters and diols have shown cytotoxic activity in non-tumoral cells (fibroblast BALB/3T3). • Se-containing α-hydroxy ester and α-hydroxy acids have shown selective antitumor activity in the B16-F10 tumoral cell line. A series of seleno-containing polyfunctionalized compounds was synthesized exploring cyanohydrin chemistry, including α-hydroxy esters, α-hydroxy acids, 1,2-diols, and 1,2-diacetates, with yields ranging from 26 up to 99 %. The cytotoxicity of all synthesized compounds was then evaluated using a non-tumor cell line (BALB/3T3 murine fibroblasts), and those deemed non-cytotoxic had their anti-melanoma activity evaluated using B16-F10 murine melanoma cells. These assays identified two compounds with selective cytotoxic activity against the tested melanoma cell line, showing a potential anti-melanoma application. [ABSTRACT FROM AUTHOR]

Understanding the complex interactions between plants and herbivores is essential for improving crop resistance. Aiming to expand the role of cyanogenesis in plant defence, we investigated the response of the cyanogenic Phaseolus lunatus (lima bean) and the non-cyanogenic Phaseolus vulgaris (common bean) to Tetranychus urticae (spider mite) infestation. Despite mite infesting both legumes, leaf damage infringed by this feeder was reduced in lima bean. Comparative transcriptome analyses revealed that both species exhibited substantial metabolic and transcriptional changes upon infestation, although alterations in P. lunatus were significantly more pronounced. Specific differences in amino acid homeostasis and key genes associated with the cyanogenic pathway were observed in these species, as well as the upregulation of the mandelonitrile lyase gene (PlMNL1) following T. urticae feeding. Concomitantly, the PIMNL1 activity increased. Lima bean plants also displayed an induction of β-cyanoalanine synthase (PlCYSC1), a key enzyme for cyanide detoxification, suggesting an internal regulatory mechanism to manage the toxicity of their defence responses. These findings contribute to our understanding of the legume-herbivore interactions and underscore the potential role of cyanogenesis in the elaboration of specific defensive responses, even within the same genus, which may reflect distinctive evolutionary adaptations or varying metabolic capabilities between species. • Cyanogenesis is a plant defense strategy involving the emission of poisonous hydrogen cyanide when plant tissues are disrupted by an herbivore. • The goal of this study was to compare the differential defense mechanisms triggered by Tetranychus urticae in two legume species, the cyanogenic Phaseolus lunatus (lima bean) and the non-cyanogenic Phaseolus vulgaris (common bean), by identifying which genes and metabolites are similar and different in these species. • Our findings demonstrate: i) leaf damage mediated by mites in P. lunatus was smaller than in P. vulgaris ; ii) both species exhibited substantial metabolic and transcriptional changes upon infestation, although alterations in P. lunatus were significantly more pronounced; iii) specific induction of genes linked to terpenoid and thiamine metabolism, changes in amino acid content and the induction of key genes linked to cyanogenesis were differentially produced in infested P. lunatus , suggesting the participation of these processes in the differential defense response; iv) a previously unannotated gene, PlMNL1 , encoding for mandelonitrile lyase in P. lunatus , was identified. PlMNL1 was mite-upregulated and the corresponding protein had mandelonitrile lyase activity; and v) A P. lunatus β-cyanoalanine synthase (PlCYSC1) is induced upon T. urticae infestation, suggesting a fine tuning mechanism between Cyanogenesis and HCN detoxification. [ABSTRACT FROM AUTHOR]

The asymmetric cyanation of acylsilanes affords densely functionalized tetrasubstituted chiral carbon centers bearing silyl, cyano, and hydroxy groups, which are of particular interest in synthetic and medicinal chemistry. However, this method has been limited to a few enzymatic approaches, which employ only one substrate because of substrate specificity. Here we show the non-enzymatic catalytic asymmetric cyanation of acylsilanes using a chiral Lewis base as an enantioselective catalyst, trimethylsilyl cyanide as a cyanating reagent, and isopropyl alcohol as an additive to drive catalyst turnover. High enantio- and site-selectivities are achieved in a catalytic manner, and a variety of functional groups are installed in optically active acylsilane cyanohydrins, thus overcoming the limitations imposed by substrate specificity in conventional enzymatic methods. A handle for the synthetic application of the products is also established through the development of a catalyst for protecting acylsilane cyanohydrins, which are unstable and difficult to protect alcohols. Catalytic asymmetric cyanation of ketones is a straightforward method to construct tetrasubstituted chiral carbon centers, but for acylsilanes this method has been limited to enzymatic approaches. Here, non-enzymatic catalytic asymmetric cyanation of acylsilanes is accomplished using a chiral Lewis base as an enantioselective catalyst. [ABSTRACT FROM AUTHOR]

A continuous flow cascade of multi-step catalytic reactions is a cutting-edge concept to revolutionize stepwise catalytic synthesis yet is still challenging in practical applications. Herein, a method for practical one-pot cascade catalysis is developed by combining Pickering emulsions with continuous flow. Our method involves co-localization of different catalytically active sub-compartments within droplets of a Pickering emulsion yielding cell-like microreactors, which can be packed in a column reactor for continuous flow cascade catalysis. As exemplified by two chemo-enzymatic cascade reactions for the synthesis of chiral cyanohydrins and chiral ester, 5 − 420 fold enhancement in the catalysis efficiency and as high as 99% enantioselectivity were obtained even over a period of 80 − 240 h. The compartmentalization effect and enriching-reactant properties arising from the biomimetic microreactor are theoretically and experimentally identified as the key factors for boosting the catalysis efficiency and for regulating the kinetics of cascade catalysis. A continuous flow cascade of multi-step catalytic reactions would provide significant advantages in faster reaction times, waste reduction, and lowered step-count of syntheses, yet this ideal remains challenging in practical applications. Here the authors describe continuous flow cascade catalysis through co-localization of two catalytically active subcompartments within Pickering emulsion droplets. [ABSTRACT FROM AUTHOR]

An interesting protocol for stereoselective synthesis of (−)‐cytoxazone and its unnatural stereoisomer (+)‐5‐epi‐cytoxazone from d‐4‐hydroxyphenylglycine in overall yields of 10% and 16%, respectively, is described. The stereoselective addition of cyanide to an N‐Boc protected aminoaldehyde (tert‐butyl ((R)‐1‐(4‐methoxyphenyl)‐2‐oxoethyl)carbamate) (5) constitutes the key step in this approach, producing a mixture of cyanohydrins 6a and b (1,2‐anti and 1,2‐syn tert‐butyl (2‐cyano‐2‐hydroxy‐1‐(4‐methoxyphenyl)ethyl)carbamate) in 89% yield, with reasonable stereoselectivity (1.0:1.8) in favor of the anti‐Felkin product (1,2‐syn). A one‐pot sequence of three successive steps from this mixture produced the oxazolidinone isomers 9a and b ((4R,5R)‐ and (4R,5S)‐4‐(4‐methoxyphenyl)‐2‐oxooxazolidine‐5‐carboxylate). Chromatographic column separation and reduction of the ester function of both precursors led to (−)‐cytoxazone and (+)‐5‐epi‐cytoxazone. [ABSTRACT FROM AUTHOR]

Synthesis and enzymatic resolution of a new class of alicyclic and heterocyclic mandelic acid derivatives was described. The method relied on the preparation of cyanohydrins from the commercially available aldehydes followed by hydrolysis to corresponding racemic hydroxy esters that were used in the resolution with the Amano PS enzyme. An alternative approach was proposed for compounds that were not suitable for this procedure. For the selected examples, synthesis of the corresponding mandelic acid analogs using the subsequent hydrolysis of esters followed by enantiomeric enrichment via recrystallization of the diastereomeric salt was performed. [Display omitted] [ABSTRACT FROM AUTHOR]

A metal‐free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β‐substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α‐functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β‐cyano esters, α‐aryl alkylnitriles, and TBS‐protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine). [ABSTRACT FROM AUTHOR]

Thermodynamic and kinetic control of a chemical process is the key to access desired products and states. Changes are made when a desired product is not accessible; one may manipulate the reaction with additional reagents, catalysts and/or protecting groups. Here we report the use of carbon dioxide to accelerate cyanohydrin synthesis under neutral conditions with an insoluble cyanide source (KCN) without generating toxic HCN. Under inert atmosphere, the reaction is essentially not operative due to the unfavored equilibrium. The utility of CO2‐mediated selective cyanohydrin synthesis was further showcased by broadening Kiliani–Fischer synthesis under neutral conditions. This protocol offers an easy access to a variety of polyols, cyanohydrins, linear alkylnitriles, by simply starting from alkyl‐ and arylaldehydes, KCN and an atmospheric pressure of CO2. [ABSTRACT FROM AUTHOR]

• Nanoceria catalyzes the cyanosilylation of different ketones at rt in high yields. • Nanoceria acts as a bifunctional acid-base solid catalyst. • The solid catalyst can be reused ten times with a simple calcination. • The catalytic activity of nanoceria is independent of the crystalline phase. • Au-nanoceria catalyzes the aerobic oxidation of alcohols/cyanosilylation reaction. The cyanosilylation of carbonyl compounds is a fundamental reaction in organic synthesis, to give cyanohydrins. Ketones are particularly reluctant to cyanosilane addition and require the action of a catalyst, and despite many soluble Brönsted and Lewis acids have been employed for this task, it is difficult to find in the open literature catalytic solids able to carry out the reaction. Here, we show that commercially available nanoceria catalyzes the cyanosilylation of different ketones (21 examples) at temperatures between 0 and 50 °C, in high yields, under solventless conditions if required. The nanoceria network atoms act in a cooperative way to provide a bifunctional acid-base solid catalyst for the cyanosilylation reaction. The amorphization of nanoceria during reaction, due to acid release, does not hamper the catalytic activity and, indeed, different types of nanoceria, even with supported metal nanoparticles on surface, are active for the reaction, enabling extensive reuses after air calcination and the use of the catalytic material for the aerobic oxidation of alcohols / cyanosilylation reaction. [ABSTRACT FROM AUTHOR]

• Bm HNL has the longest half-life among all currently known α/β hydrolase fold HNLs at its optimal pH and temperature. • Polyol addition increases Bm HNL's stability and activity. • Glycerol addition to Bm HNL biocatalysis increases % ee of the synthesized cyanohydrins. HNL catalysis is usually carried out in a biphasic solvent and at low pH to suppress the non-enzymatic synthesis of racemic cyanohydrins. However, enzyme stability under these conditions remain a challenge. We have investigated the effect of different biocatalytic parameters, i.e., pH, temperature, buffer concentrations, presence of stabilizers, organic solvents, and chemical additives on the stability of Baliospermum montanum hydroxynitrile lyase (Bm HNL). Unexpectedly, glycerol (50 mg/mL) added Bm HNL biocatalysis had produced >99% of (S)-mandelonitrile from benzaldehyde, while without glycerol it is 54% ee. Similarly, Bm HNL had converted 3-phenoxy benzaldehyde and 3,5-dimethoxy benzaldehyde, to their corresponding cyanohydrins in the presence of glycerol. Among the different stabilizers added to Bm HNL at low pH, 400 mg/mL of sucrose had increased enzyme's half-life more than fivefold. Bm HNL's stability study showed half-lives of 554, 686, and 690 h at its optimum pH 5.5, temperature 20 °C, buffer concentration, i.e., 100 mM citrate-phosphate pH 5.5. Addition of benzaldehyde as inhibitor, chemical additives, and the presence of organic solvents have decreased both the stability and activity of Bm HNL, compared to their absence. Secondary structural study by CD-spectrophotometer showed that Bm HNL's structure is least affected in the presence of different organic solvents and temperatures. [ABSTRACT FROM AUTHOR]

2,3-Secooleanane hydroxynitriles undergo dehydration and anionotropic 1,2-migration of the methyl group C(24)H3 under the action of the SOCl2-CH2Cl2 system to form a mixture of isomeric Δ4-alkenes. A similar E1-elimination process in the presence of the H2SO4—AcOH system is accompanied by hydrolysis of the CN group giving A-ring unsaturated C(2)-ketones and diastereomeric ε-lactones. Epimeric 4,23-epoxides and isopropyl ketone were synthesized by oxidative transformations of 4,23-alkene, which was selectively formed from 2,3-secooleanane hydroxynitrile under the action of the POCl3-Py system. The in vitro cytotoxic evaluation by the MTT assay showed that the synthesized compounds are not toxic (IC50 > 100 μmol L−1) against the human cancer cell lines HEp-2, HCT116, MS, RD TE32, MCF-7, A549, and PC-3. [ABSTRACT FROM AUTHOR]

Catalytic asymmetric cyanation reactions of aldehydes and ketones provide efficient routes for the synthesis of optically active cyanohydrins, which are versatile synthons for the preparation of natural products and chemical pharmaceuticals. This review aims to provide a summary of recent achievements concerning catalytic enantioselective cyanation reactions of aldehydes and ketones employed in the total syntheses of various natural products, drugs, and pharmaceutically active compounds. [ABSTRACT FROM AUTHOR]

The first example of divergent synthesis of functionalized 2,3-dihydrofuran and 2,3-dihydropyrrole derivatives via a Lewis base-catalysed hydroalkoxylation/Claisen rearrangement/Michael addition tandem sequence is reported. The operational simplicity of the method allows for greater efficiency in the synthesis of a wide range of functionalized 2,3-dihydrofurans and 2,3-dihydropyrroles from readily accessible allylic cyanohydrins and activated alkynes in good to excellent yields under optimal conditions. [ABSTRACT FROM AUTHOR]

Abstract A Novel chemosensor R possessing napthoquinone substituted benzaldehyde has been successfully designed, synthesized and characterized using NMR and mass spectral techniques. The receptor exhibits striking colour change from pale yellow to intense green with sodium cyanide in DMF-H 2 O (80–20% v/v) in a wide range of pH (3−12). Based on the results of spectral (UV–Vis, fluorescence and NMR), electrochemical and kinetic studies a plausible mechanism has been proposed for the cyanide detection process. The mechanism of sensing of cyanide by R is through the formation of cyanohydrin in acidic, neutral and basic solutions, which is the novelty of the receptor. The pseudo-first-order rate constants for the formation of cyanohydrin are found to be 2.9 × 10−3, 3.9 × 10−3 and 4.6 × 10−3 min−1 at pH values 5, 7 and 10, respectively in DMF-H 2 O (80–20% v/v) medium, supporting the ability of R to form cyanohydrin with equal ease in different pH values. The results of Job's continuous variation method indicates a 1:2 (R :CN−) stoichiometry for the interaction. The only minor drawback with the receptor is the time taken to impart visible colour change with cyanide ion, which is not instantaneous. Graphical Abstract Unlabelled Image Highlights • The receptor colorimetrically senses cyanide in 3–12 pH range. • The mechanism of sensing involves cyanohydrin formation by formyl group. • The sensing is equally ease in acidic, neutral and basic media. [ABSTRACT FROM AUTHOR]

Supported Ionic Liquid‐Like Phases have been found to be efficient organocatalysts for the synthesis of cyanohydrin esters under solvent‐free conditions by an "electrophile‐nucleophile dual activation" based on hydrogen bond formation. The combination of multiple and consecutive multicatalytic steps in a single and integrated cascade process of organocatalytic SILLPs with commercially available supported Candida antarctica lipase type B (CAL‐B) has allowed developing an efficient process for the multicatalytic synthesis of enantiopure cyanohydrins under flow conditions. Step it up: An integrated cascade multicatalytic multiple step flow process based on the appropriated combination of organocatalytic supported ionic liquid‐like phases (SILLPs) together with commercially available supported Candida antarctica lipase type B (CAL‐B) is reported for the efficient synthesis of enantiopure cyanohydrins. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Preparation and characterization of CLEA- Bm HNL reported first time. • Reusability of CLEA- Bm HNL in (S)-cyanohydrin synthesis up to eight cycles without loss of conversion. • CLEA has improved enantioselectivity of (S)-cyanohydrin synthesis compared to the use of purified enzyme. • Among the 11 (S)-cyanohydrins synthesized here, 8 were not synthesized by any CLEA-HNL and 9 were not tested by BmHNL earlier. Abstract Hydroxynitrile lyase (HNL) catalyzed enantioselective C C bond formation is an efficient approach to synthesize chiral cyanohydrins which are important building blocks in the synthesis of a number of fine chemicals, agrochemicals and pharmaceuticals. Immobilization of HNL is known to provide robustness, reusability and in some cases also enhances activity and selectivity. We optimized the preparation of immobilization of Baliospermium montanum HNL (Bm HNL) by cross linking enzyme aggregate (CLEA) method and characterized it by SEM. Optimization of biocatalytic parameters was performed to obtain highest % conversion and ee of (S)-mandelonitrile from benzaldehyde using CLEA- Bm HNL. The optimized reaction parameters were: 20 min of reaction time, 7 U of CLEA- Bm HNL, 1.2 mM substrate, and 300 mM citrate buffer pH 4.2, that synthesized (S)-mandelonitrile in ∼99% ee and ∼60% conversion. Addition of organic solvent in CLEA- Bm HNL biocatalysis did not improve in % ee or conversion of product unlike other CLEA-HNLs. CLEA- Bm HNL could be successfully reused for eight consecutive cycles without loss of conversion or product formation and five cycles with a little loss in enantioselectivity. Eleven different chiral cyanohydrins were synthesized under optimal biocatalytic conditions in up to 99% ee and 59% conversion, however the % conversion and ee varied for different products. CLEA- Bm HNL has improved the enantioselectivity of (S)-mandelonitrile synthesis compared to the use of purified Bm HNL. Nine aldehydes not tested earlier with Bm HNL were converted into their corresponding (S)-cyanohydrins for the first time using CLEA- Bm HNL. Among the eleven (S)-cyanohydrins syntheses reported here, eight of them have not been synthesized by any CLEA-HNL. Overall, this study showed preparation, characterization of a stable, robust and recyclable biocatalyst i.e. CLEA- Bm HNL and its biocatalytic application in the synthesis of different (S)-aromatic cyanohydrins. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two new binuclear Zn(II) complexes (1–2) and one trinuclear Cu(II) (3) complex are synthesized using biphenol-framework tetradentate N2O2 donor ligands. • All the complexes have been structurally characterized using single crystal X-ray crystallography, mass spectrometry, FTIR, UV–Vis and elemental analysis. • It has been shown that a single tetradentate N2O2 donor ligand form both binuclearZn(II) & trinuclear Cu(II) complexes under similar conditions. • Both the binuclear Zn(II) (1–2) complexes demonstrate excellent catalytic activity in the cyanosilylation reaction of several aryl aldehydes into value-added cyanohydrins at room temperature and without the use of solvents. In this work, two dinuclear Zn(II) complexes [Zn(H 2 L1)] 2 (complex 1), [Zn(H 2 L2)] 2 (complex 2), and a trinuclear Cu(II) complex [Cu(H 2 L2)] 3 (complex 3) (H 2 L1 = 3,3′- bis -[(2,6-dimethyl-phenylimino)-methyl]-[1,1′]-biphenyl-2,2′-diol, H 2 L 2 = 2,6-diethyl phenylimino)-ethyl]-[1,1′]-biphenyl-2,2′- diol) are reported. The complexes 1 , 2 & 3 have been produced and isolated for the first time in a well-defined and air-stable form by reacting biphenol-based tetradentate N2O2-type (H 2 L1 and H 2 L2) ligands with the respective metal acetate salts. The synthesised compounds were characterized by UV–Vis spectroscopy, elemental analysis, mass spectrometry and Fourier-transform infrared spectroscopy (FT-IR). Single crystal X-ray diffraction (SCXRD) study revealed distorted tetrahedral geometry surrounding the core Zn2+ cations (1 – 2) that were bridging the teradentate N2O2 ligands. In complex- 3 , the Cu(II) center is four-coordinated via tetradentate N2O2 donor ligand, forming slightly distorted square planar geometry with an angular C 2-symmetric core and exhibits weak antiferromagnetic (AF) interactions. Hirshfeld surface analysis and fingerprint plots were used to investigate the intermolecular interactions in the crystalline state. Strong H...H and H... C/C...H intermolecular interactions were seen on the Hirshfeld surface when it was mapped over d norm , shape index, and curvature. These interactions were found to be the main contributors to crystal packing. Excellent catalytic activity was demonstrated for the dinuclear zinc(II) complexes [Zn(H 2 L1)] 2 (1)and [Zn(H 2 L2)] 2 (2) in the cyanosilylation reaction of various aryl aldehydes into value-added cyanohydrins at room temperature and under solvent free conditions. [ABSTRACT FROM AUTHOR]

Asymmetric 1,2‐additions of cyanide yield enantioenriched cyanohydrins as versatile chiral building blocks. Next to HCN, volatile organic cyanide sources are usually used. Among them, cyanoformates are more attractive on technical scale than TMSCN for cost reasons, but catalytic productivity is usually lower. Here, the development of a new strategy for cyanations is described, in which this activity disadvantage is overcome. A Lewis acidic Al center cooperates with an aprotic onium moiety within a remarkably robust bifunctional Al–F–salen complex. This allowed for unprecedented turnover numbers of up to 104. DFT studies suggest an unexpected unique trimolecular pathway in which the ammonium bound cyanide attacks the aldehyde, which itself is activated by the carbonyl group of the cyanoformate binding to the Al center. In addition, a novel practical carboxycyanation method was developed that makes use of KCN as the sole cyanide source. The use of a pyrocarbonate as carboxylating reagent provided the best results. Trimolecular? The evolution of a robust, highly active catalyst for asymmetric aldehyde cyanations is reported, which in the final synthetic protocol uses inorganic KCN instead of volatile organic cyanation reagents. DFT studies for the initial protocol using a cyanoformate reagent suggest a unique trimolecular reaction pathway. [ABSTRACT FROM AUTHOR]

An asymmetric cyanation of acylsilanes involving the in‐situ formation of chiral acylsilane cyanohydrins followed by their kinetic resolution via organocatalytic cycloetherification is described. The highly enantio‐ and diastereoselective cycloetherification was crucial for achieving a high efficiency in the kinetic resolution. Consequently, acylsilane cyanohydrins containing a tetrasubstituted chiral carbon atom bearing silyl, cyano, and hydroxy groups were obtained in an enantioenriched form. This protocol therefore offers an efficient catalytic approach to optically active acylsilane cyanohydrins, which exhibit potential as chiral building blocks for the synthesis of pharmaceutically relevant chiral organosilanes. An asymmetric cyanation of acylsilanes involving the in‐situ formation of chiral acylsilane cyanohydrins followed by their kinetic resolution via organocatalytic cycloetherification is described. The highly enantio‐ and diastereoselective cycloetherification was crucial for achieving a high efficiency in the kinetic resolution. Consequently, acylsilane cyanohydrins containing a tetrasubstituted chiral carbon atom bearing silyl, cyano, and hydroxy groups were obtained in an enantioenriched form. [ABSTRACT FROM AUTHOR]

In this study, the crude solution of Prunus armeniaca hydroxynitrile lyase (ParsHNL) was simultaneously precipitated onto K2SO4 salt in acetone to immobilize ParsHNL as protein-coated microcrystals and the obtained preparations (PCMCs-ParsHNL) were used for the synthesis of (R)-mandelonitrile in buffer-saturated methyl tert-butyl ether (pH 4.0). The yield and enantiopurity of (R)-mandelonitrile were 100 and 90.5%, respectively, for free HNL, whereas the corresponding yield and enantiopurity values were 100 and 99.8%, respectively, for PCMCs-ParsHNL after 96 h reaction time. The free HNL and PCMCs-ParsHNL were stored at room temperature and 5 °C during 30 days and the results showed that PCMCs-ParsHNL had better storage stability compared to the free HNL at both room temperature and 5 °C. PCMCs-ParsHNL was imaged by a scanning electron microscopy and PCMCs-ParsHNL was rectangular in shape. PCMCs-ParsHNL was recycled five times in the synthesis of (R)-mandelonitrile and 75.2% initial activity recovery and 99.8% enantiomeric excess for (R)-mandelonitrile was determined after five uses. Thus, immobilizing ParsHNL as PCMCs provided highly active and reusable HNL preparations for (R)-mandelonitrile synthesis in buffer-saturated methyl tert-butyl ether. [ABSTRACT FROM AUTHOR]

A chemoselective phosphine-catalyzed cyanoacylation of α-dicarbonyl compounds is reported. Under the catalysis of P(NMe2)3, the cyanoacylation of α-dicarbonyl compounds such as isatins, α-keto esters, and α-diketones with acyl cyanides exclusively proceeds under very mild conditions, affording a wide range of cyanohydrin esters bearing one quaternary stereocenter in moderate to excellent yields. It represents the first phosphine-catalyzed cyanoacylation of α-dicarbonyl compounds and also provides a general method to prepare fully substituted cyanohydrin esters. [ABSTRACT FROM AUTHOR]

Hydroxynitrile lyases (HNLs) are widely used in the asymmetric synthesis of cyanohydrins which are organic compounds used in the production of fine chemicals and pharmaceuticals, because these enzymes exhibit high catalytic efficiency and are very economical. In the present study, seeds of A. pedunculata Pall were identified as new potential source of HNLs. The HNL from A. pedunculata Pall (APHNL) was purified 138 fold and 4.20% yield with a specific activity of 661 U/mg. SDS-PAGE result showed the enzyme to be present as a monomer and the relative molecular mass determined by MALDI-TOF MS was 61 kDa. APHNL owned highest activity at pH 6.0 and at 60 °C temperature, showing activity up to 80 °C and stable up to 60 °C. APHNL has a Km of 0.5 mM, Vmax of 665.9 μmol mg −1  min −1 , Kcat of 676.5 s −1 and Kcat / Km of 1353 s −1  mM −1 using mandelonitrile as substrate. Syntheses of ( R )-mandelonitrile and ( R )-2-Hydroxy-2-(3-phenoxy-phenyl)-acetonitrile were carried out using APHNL and molar conversion of ( R )-mandelonitrile and ( R )-2-Hydroxy-2-(3-phenoxy-phenyl)-acetonitrile were 90% and 98% with 94% and 93% ee, respectively. These results indicated that APHNL was an excellent biocatalyst and has very high potential for synthesis of enantiopure cyanohydrins. [ABSTRACT FROM AUTHOR]

Abstract This study presents asymmetric synthesis of cyanohydrins in aqueous–organic biphasic system using crude Baliospermum montanum hydroxynitrile lyase (Bm HNL). The effect of various biocatalytic parameters e.g. different organic solvents, ratio of organic solvents, substrate concentration (benzaldehyde and HCN), pH, and temperature were studied to achieve highest % conversion and enantiomeric excess of (S)-mandelonitrile. Among the organic solvents i.e. hexane, toluene, acetonitrile, tert -butyl methyl ether (TBME), di -isopropyl ether (DIPE) and n -butyl acetate studied, 10% n -butyl acetate showed best results. Optimal results were also found with 0.8 mM benzaldehyde, 10 min reaction time, pH 4.2 and substrate to KCN ratio of 1:125. Under optimal biocatalytic conditions more than a dozen of different aromatic aldehydes were converted into corresponding chiral (S)-cyanohydrins. This method also reports the synthesis of eight chiral (S)-cyanohydrins for the first time, not synthesized by any (S)-selective HNL earlier. Graphical abstract fx1 Highlights • Bm HNL catalyzed synthesis of (S)-cyanohydrins was studied for the first time in biphasic media. • Use of crude Bm HNL in biocatalysis have resulted in comparable % ee and conversion of products with that of the use of purified enzymes in case of a few substrates. • Sixteen (S)-cyanohydrins were synthesized using Bm HNL in biphasic media. • Thirteen (S)-cyanohydrins were synthesized by Bm HNL for the first time and eight among them have not been synthesized by any other (S)-selective HNL except this report. [ABSTRACT FROM AUTHOR]

The present review deals with the ring-opening of epoxides by various carbon, nitrogen, oxygen, halogen, and sulfur-containing nucleophiles, which most of the resulting products are versatile intermediates in the synthesis of various biologically active compounds. The regioselectivity and environmentally benign nature of procedures for the synthesis of similar products have been also discussed in detail. [ABSTRACT FROM AUTHOR]

The promoting effect of smoke-derived chemicals (e.g. karrikinolide and cyanohydrin) on germination in many plants from Mediterranean-type ecosystems such as South Africa and south-western Australia is well documented. However, very little is known about (1) the relative importance of different compounds and their possible interactive effects, (2) their role in enhancing seedling growth in wild plants, and (3) their effect on the germination of plants in the Mediterranean Basin. To fill these gaps in knowledge, we performed experiments to evaluate the effect of smoke water, karrikinolide, mandelonitrile (a cyanohydrin analogue), potassium nitrate and gibberellic acid on the germination and seedling growth of 37 species from the Mediterranean Basin. The results suggest that germination and/or seedling growth of 21 species are enhanced by at least one of the fire-derived chemicals. There were positive correlations between most of the compounds tested in terms of germination response, but synergetic and inhibitory effects were also detected. Stimulation of germination was most prominent in species with annual life cycles. Fire-derived chemicals were more effective in stimulating root growth than shoot growth. In conclusion, we provide novel evidence that the recruitment of different Mediterranean species may be enhanced by different smoke compounds, and that synergetic and inhibitory effects of chemical compounds are important in the germination ecology of plants. [ABSTRACT FROM AUTHOR]

Two known lanthanide complexes, [KLa(HL 1 ) 2 {(CH 3 ) 2 NCHO} 2 (H 2 O) 3 ] ( 1 ) and [Sm(H 2 O) 9 ]( E -H 2 L 2 ) 3 ·2H 2 O ( 2 ) were prepared by reaction of lanthanum(III) and samarium(III) nitrates with potassium 3-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonate (KH 2 L 1 ) and potassium ( E,Z )-5-chloro-3-(2-(1,3-dioxo-1-phenylbutan-2-ylidene)hydrazinyl)-2-hydroxybenzenesulfonate (KH 2 L 2 ), respectively. Catalytic activities of 1 and 2 were evaluated in the cyanosilylation of aldehydes with trimethylsilyl cyanide in different solvents such as tetrahydrofuran, dichloromethane or methanol. Complex 1 was found to be efficient catalyst for the cyanosilylation reaction in methanol medium at room temperature, producing cyanohydrin trimethylsilyl ethers with good yields (76–99%). [ABSTRACT FROM AUTHOR]

Fe 3 O 4 /SiO 2 core-shell hybrid nanoparticles covalently attached to graphene oxide (Fe 3 O 4 /SiO 2 /PTS-GO) were prepared and fully characterized using different techniques including Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The efficiency of Fe 3 O 4 /SiO 2 /PTS-GO nanocomposite was demonstrated in trimethylsilyl cyanide (TMSCN) addition to a wide range of aldehydes and ketones in high to quantitative yields under extremely mild conditions. Low catalyst loading, reusability of the catalyst, avoiding the use of any hazardous solvent, short reaction time at ambient temperature and straightforward work up procedure are some of the attractive advantages of this protocol. [ABSTRACT FROM AUTHOR]

Spiroconnected N-alkoxyalkylpiperidine hydantoins were obtained via the Strecker reaction of cyanohydrin with ammonium carbonate. 1,3,8-Triazaspiro[4.5]decane-2,4-diones have shown the myelostimulating activity in the artificially induced (with cyclophosphamide) myelodepressive syndrome. The compounds significantly accelerated the regeneration of lymphocyte and granulocyte cell pool of bone marrow hematopoiesis. [ABSTRACT FROM AUTHOR]

Histone deacetylases (HDACs) play essential roles in transcription regulation and are valuable theranostic targets. However, there are no activatable fluorescent probes for imaging of HDAC activity in live cells. Here, we develop for the first time a novel activatable two-photon fluorescence probe that enables in situ imaging of HDAC activity in living cells and tissues. The probe is designed by conjugating an acetyl-lysine mimic substrate to a masked aldehyde-containing fluorophore via a cyanoester linker. Upon deacetylation by HDAC, the probe undergoes a rapid self-immolative intramolecular cyclization reaction, producing a cyanohydrin intermediate that is spontaneously rapidly decomposed into the highly fluorescent aldehyde-containing twophoton fluorophore. The probe is shown to exhibit high sensitivity, high specificity, and fast response for HDAC detection in vitro. Imaging studies reveal that the probe is able to directly visualize and monitor HDAC activity in living cells. Moreover, the probe is demonstrated to have the capability of twophoton imaging of HDAC activity in deep tissue slices up to 130 µm. This activatable fluorescent probe affords a useful tool for evaluating HDAC activity and screening HDAC-targeting drugs in both live cell and tissue assays. [ABSTRACT FROM AUTHOR]

Fermentation is one ways to reduce cyanogenic compounds in cassava. Fermentation of cassava is usually performed by submerged fermentation and solid state fermentation separately. "Gadungan pohung" is one of Indonesian traditional of cassava fermentations that combines spontaneous submerged and solid state fermentation simultantly. The objective of this study was to evaluate some chemical compound changes, microbiological profile, and cyanides reduction of three high cyanide cassava varieties during 3 days submerged fermentation and 3 days solid state fermentation simultaneously, in "gadungan pohung" processing. The resuls showed that submerged and solid state fermentation decreased most of nutritonal compounds of cassava except carbohydrate. Submerged fermentation reduced pH value from 6 to 4.5, meanwhile solid state fermentation increased pH value from 4.5 to 6. All cassava varieties revealed similar changes. Bacteria, mainly lactic acid bacteria, dominated during submerged and solid state fermentation. Yeasts were also found in higher number than molds. Cassava varieties slightly affected the pattern of microbial growth during solid state fermentation. Submerged fermentation reduced cyanide compounds. Some cyanide compounds were found in fermenting medium. Significant declined was found in cyanogenic glycosides, meanwhile cyanohydrin and free HCN increased in all cassava varieties. Solid state fermentation decreased cyanogenic glycosides and cyanohydrin, meanwhile concentration of free HCN were fluctuated during 3 days fermentation. Degradation of cyanides in solid state fermentation was due to microbial activity and increasing pH to above 5. Combination of submerged and solid state fermentation effectively reduced cyanide compounds in high cyanide cassava varieties to about 89-93%. [ABSTRACT FROM AUTHOR]

Acetals of the cyanohydrins of aromatic aldehydes were deprotonated to generate carbanions, which were used in the vicarious nucleophilic substitution of the hydrogen atom of aromatic and heteroaromatic nitro compounds to form p-nitrosubstituted diarylacetonitriles. The reaction selectively occurred para to the nitro group. The anion of the hemiacetal of acetaldehyde was shown to be an efficient leaving group in the base-induced β-elimination step. [ABSTRACT FROM AUTHOR]

Hydroxynitrile lyases (HNLs) are enzymes used in the synthesis of chiral cyanohydrins. The HNL from Passiflora edulis (PeHNL) is R‐selective and is the smallest HNL known to date. The crystal structures of PeHNL and its C‐terminal peptide depleted derivative were determined by molecular replacement method using the template structure of a heat stable protein, SP1, from Populus tremula at 2.8 and 1.8 Å resolution, respectively. PeHNL belongs to dimeric α+β barrel superfamily consisting of a central β‐barrel in the middle of a dimer. The structure of PeHNL complexed with (R)‐mandelonitrile ((R)‐MAN) was also determined. The hydroxyl group of (R)‐MAN forms hydrogen bonds with His8 and Tyr30 in the active site, whereas the nitrile group is oriented toward the carboxyl group of Glu54, unlike other HNLs, where it interacts with basic residues typically. The results of mutational analysis indicate that the catalytic dyad of His8‐Asn101 is critical for the enzymatic reaction. The length of the hydrogen bond between His‐Nδ1 and Asn101‐Oδ1 is short in the PeHNL‐(R)‐MAN complex (~ 2.6 Å), which would increase the basicity of His8 to abstract a proton from the hydroxyl group of (R)‐MAN. The cyanide ion released from the nitrile group abstracts a proton from the protonated His8 to generate a hydrogen cyanide. Thus, the His8 in the active site of PeHNL acts both as a general acid and a general base in the reaction. Enzymes: EC 4.1.2.10 Database: Structural data are available in PDB database under the accession numbers 5XZQ, 5XZT, and 5Y02. [ABSTRACT FROM AUTHOR]