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The beneficial effects of smoke and its constituents, karrikinolide (KAR1) and cyanohydrin glyceronitrile, on the germination of Mediterranean lowland species are well‐documented. However, very little is known about the role of these signals on the germination of plants at higher altitudes. In addition, lignin‐derived chemicals, such as syringaldehyde (SAL), have recently been proposed as overlooked cues for smoke‐induced germination. To address these gaps in the literature, we investigated the effects of smoke‐water and SAL on the germination of 10 midland species growing on serpentine soils. We also sought to determine whether SAL interacts with KAR1 and/or mandelonitrile (MAN, a cyanohydrin) to enhance seed germination. The results show that smoke‐water significantly improved the germination of three species (Barbarea duralii, Digitalis cariensis and Turritis laxa). SAL, on the other hand, had no positive effect on the germination of the 10 species tested. Furthermore, three smoke‐sensitive species and Verbascum cariense responded to KAR1 and/or MAN. Finally, SAL did not exert any synergistic effects on germination in interaction with KAR1 and MAN. In conclusion, we provide evidence that smoke is an important germination cue also for Mediterranean midland species. Moreover, SAL did not play a role in stimulating germination in smoke‐sensitive species, either independently or in combination with other smoke chemicals. [ABSTRACT FROM AUTHOR]

Smoke and smoke-derived compounds can regulate physiological and developmental processes, such as seed germination, somatic embryogenesis, and flowering in plants. Smoke-related germination responses are highly complex due to the presence of stimulatory and inhibitory compounds, such as karrikins, glyceronitrile, syringaldehyde, catechol, and 3,4,5-trimethylfuran-2(5H)-one. In this study, the effects of smoke water, karrikinolide (KAR1), mandelonitrile (MAN), and catechol (CAT) treatments on seed germination of Liquidambar orientalis Mill. were investigated. Moreover, gibberellic acid (GA3) and reactive oxygen species (ROS), which are thought to play a role in KAR1- and cyanohydrin-induced seed germination, were also included in the experiments. Hydrogen peroxide and methyl viologen solutions were used for ROS treatments. Germination experiments were carried out under different light conditions in incubators set at 20 °C. The results of the study showed that L. orientalis seeds were sensitive to smoke. In addition, 0.01 and 0.1 µM KAR1 and 50 µM MAN solutions promoted the germination of the study species under both dark and light conditions (p < 0.05). On the other hand, CAT treatments did not have a positive or negative effect on germination. L. orientalis seeds sensitive to KAR1 and cyanohydrin gave a positive germination response to GA3 in the concentration range of 10-5 to 10-3 M. GA3 treatments also eliminated the requirement of light for high germination success. ROS-induced germination was only observed in the presence of light. The findings of this study can be used to increase the germination success of L. orientalis, a narrowly distributed species. [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 generation of the quaternary stereocenter at the C9 position of salvinorin A precursors by the Claisen rearrangement was investigated. The required allyl alcohol was prepared from a Wieland‐Miescher ketone using a known γ‐hydroxylation, reduction of the enone double bond, cyanohydrin formation, and elimination, yielding an unsaturated nitrile. A two‐step reduction led to the required allyl alcohol. The subsequent Johnson‐Claisen rearrangement provided a mixture of two diastereomeric 1,4‐unsaturated esters in a ratio of around 2.6 : 1. The major isomer could be converted to a key intermediate of the Hagiwara synthesis of salvinorin A. [ABSTRACT FROM AUTHOR]

The culture filtrate extract of golden bootleg (Phaeolepiota aurea) exhibited strong antifungal activity in a bioassay for volatile compounds. Purification of active compounds through silica gel column chromatography and high performance liquid chromatography isolated two compounds, 1 and 2, with molecular weights of 234 and 259, respectively, as confirmed by mass spectrometry. Nuclear magnetic resonance analysis identified these compounds as new sesquiterpenoids with the α-bourbonene skeleton. Both compounds had an aldehyde group, while 2 possessed a cyanohydrin group. These compounds were named phaeolep aldehydes A (1) and B (2). Phaeolep aldehyde A inhibited hyphae elongation of Penicillium citrinum, Aspergillus niger, Cladosporium sphaerospermum, and Alternaria brassicicola at 10 ppm, but did not exhibit any antibacterial activity. In contrast, phaeolep aldehyde B exhibited potent inhibitory effects on the spore germination of Pe. citrinum, achieving 58.2% inhibition at 0.25 ppm, outperforming phaeolep aldehyde A, which exhibited 25.7% inhibition at 10 ppm., (© The Author(s) 2024. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Abstract The generation of the quaternary stereocenter at the C9 position of salvinorin A precursors by the Claisen rearrangement was investigated. The required allyl alcohol was prepared from a Wieland‐Miescher ketone using a known γ‐hydroxylation, reduction of the enone double bond, cyanohydrin formation, and elimination, yielding an unsaturated nitrile. A two‐step reduction led to the required allyl alcohol. The subsequent Johnson‐Claisen rearrangement provided a mixture of two diastereomeric 1,4‐unsaturated esters in a ratio of around 2.6 : 1. The major isomer could be converted to a key intermediate of the Hagiwara synthesis of salvinorin A.

A variety of cyanohydrin carbonates were readily prepared by the reaction of aldehydes with cyanoformate under the influence of γ-alumina using a convenient one-pot procedure. [ABSTRACT FROM AUTHOR]

The review focuses on the iron‐catalyzed cyanation reaction. This is the first review on this topic and covers literature till 2020 and comprehends all the works published in this field detailing the scope and limitations. The cyano compounds are important organic moiety and are widely used in synthetic organic chemistry; this review aims to help understand the various aspects of Fe‐catalyzed cyanation reactions and its scope. [ABSTRACT FROM AUTHOR]

Quaternary stereocenters are privileged structural motifs, widely distributed in natural products and in pharmaceutically active compounds. Asymmetric methods for the efficient construction of these prominent frameworks are rapidly increasing. Biocatalysis represents an alternative to the existing methods of using hazardous metals and chemicals. Enzymes discussed in this mini‐review involve thiamine‐bisphosphate (ThDP)‐dependent lyases, aldolases and hydroxynitrile lyases. The chiral products, (α‐alkyl‐α‐hydroxy ketones, α‐alkyl‐α‐hydroxy‐β‐diketones, β‐hydroxy ketones, ketone cyanohydrins) obtained by these enzymes, are valuable intermediates suitable for further transformations affording a variety of multi‐functionalized useful building blocks bearing a tetrasubstituted stereocenter, such as amino alcohols, diols, α‐hydroxy carboxylic acids, β‐hydroxy‐α‐amino acids to cite only a few. [ABSTRACT FROM AUTHOR]

A novel organocatalytic multicomponent cyanovinylation of aldehydes was designed for the synthesis of conjugated cyanomethyl vinyl ethers. The reaction was implemented for the synthesis of a 3-substituted 3-(cyanomethoxy)acrylates, using aldehydes as substrates, acetone cyanohydrin as the cyanide anion source, and methyl propiolate as the source of the vinyl component. The multicomponent reaction is catalyzed by N-methyl morpholine (2.5 mol%) to deliver the 3-(cyanomethoxy)acrylates in excellent yields and with preponderance of the E-isomer. The multicomponent reaction manifold is highly tolerant to the structure and composition of the aldehyde (aliphatic, aromatic, heteroaromatics), and it is instrumentally simple (one batch, open atmospheres), economic (2.5 mol% catalyst, stoichiometric reagents), environmentally friendly (no toxic waste), and sustainable (easy scalability).

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]

We report the first application of Layered Double Hydroxides (LDHs) as efficient and novel heterogeneous catalyst for the cyanosilylation of aldehydes with excellent yields and simple work up. The reaction between different aldehydes with electron-withdrawing and releasing groups and trimethylsilyl cyanide (TMSCN) proceeds in dry CH2Cl2 at room temperature in the presence of Mg-Al-Cu LDH. The catalyst recycled and reused for four times without loss of catalytic activity. The structures of all compounds were corroborated spectroscopically (1H- and 13C-NMR, and elemental analysis). A plausible mechanism for this type of reaction is proposed. [ABSTRACT FROM AUTHOR]

The leaves of Nandina domestica Thunb. exhibited high hydroxynitrile lyase (HNL) activity in (R)-mandelonitrile synthesis. The specific activity of young leaves was significantly higher than that of mature leaves. We isolated two HNLs with molecular mass of 24.9 kDa (NdHNL-S) and 28.0 kDa (NdHNL-L) from the young leaves. Both NdHNLs were composed of two identical subunits, without FAD and carbohydrates. We purified NdHNL-L and revealed its enzymatic properties. The whole deduced amino acid sequence of NdHNL-L was not homologous to any other HNLs, and the specific activity for mandelonitrile synthesis by NdHNL-L was higher than that by other plant HNLs. The enzyme catalyzed enantioselective synthesis of (R)-cyanohydrins, exhibited high activity at pH 4.0, and high stability in the pH range of 3.5-8.0 and below 55°C. Thus, NdHNL-L is a novel HNL with novel amino acid sequence and has a potential for the efficient production of (R)-cyanohydrins. [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]

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]

The consecutive radical/ionic reaction consisting of radical formylation of alkyl bromides and nucleophilic addition of a cyanide ion was investigated, which gave moderate to good yields of cyanohydrin derivatives in one-pot.

Ruthenium-catalyzed dehydrogenation of cyanohydrins under acceptorless and base-free conditions was demonstrated for the first time in the synthesis of acyl cyanide. As opposed to the thermodynamically preferred elimination of hydrogen cyanide, the dehydrogenation of cyanohydrins could be kinetically controlled with ruthenium (II) bidentate phosphine complexes. The effects of the arene, phosphine ligands and counter anions were investigated in regard to catalytic activity and selectivity. Selective dehydrogenation can occur via β-hydride elimination with the experimentally observed [(alkoxide)Ru] complex. [ABSTRACT FROM AUTHOR]

Hydroxynitrile lyases (HNLs) are increasingly finding application in the synthesis of enantiomerically pure cyanohydrins which are important intermediates in the production of pharmaceuticals and agrochemicals. Synthesis of enantiopure mandelonitrile was carried out using HNL of wild apricot ( Prunus armeniaca L.) [ ParsHNL] in aqueous/organic biphasic system. The optimum pH and temperature of the reaction were 4.0 and 15 °C respectively, which are important parameters to suppress the non-enzymatic catalysis. ParsHNL catalyses synthesis of ( R)-mandelonitrile in methyl- tbutyl ether (MTBE)/citrate buffer biphasic system with >99% ee. Synthesis of mandelonitrile was carried out in batch reaction at 40 ml scale and finally 2.7 mmoles of ( R)-mandelonitrile was recovered which corresponded to 90% molar conversion in 46 h reaction. In fed batch reaction 6.37 mmoles of ( R)-mandelonitrile could be produced which corresponds to 91% molar conversion in 46 h. In both reactions, enzyme produces ( R)-mandelonitrile with > 99% ee which showed enhanced selectivity as compared to aqueous reaction (96% ee) by ParsHNL. The results showed potential of ParsHNL to synthesize ( R)-mandelonitrile in both, batch reaction and fed-batch reaction and can be effectively used in the synthesis of ( R)-mandelonitrile. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Mandelonitrile is a nitrogen-containing compound, considered an essential secondary metabolite. Chemically, it is a cyanohydrin derivative of benzaldehyde, with relevant functions in different physiological processes including defense against phytophagous arthropods. So far, procedures for detecting mandelonitrile have been effectively applied in cyanogenic plant species such as Prunus spp. Nevertheless, its presence in Arabidopsis thaliana , considered a non-cyanogenic species, has never been determined. Here, we report the development of an accurate protocol for mandelonitrile quantification in A. thaliana within the context of A. thaliana -spider mite interaction. First, mandelonitrile was isolated from Arabidopsis rosettes using methanol; then, it was derivatized by silylation to enhance detection and, finally, it was quantified using gas chromatography-mass spectrometry. The selectivity and sensitivity of this method make it possible to detect low levels of mandelonitrile (LOD 3 ppm) in a plant species considered non-cyanogenic that, therefore, will have little to no cyanogenic compounds, using a small quantity of starting material (≥100 mg)., Competing Interests: Competing interests The authors declare no financial and non-financial competing interests., (Copyright © 2023 The Authors; exclusive licensee Bio-protocol LLC.)

The asymmetric unit of the title compound, C14H22N2O2Si2, contains one half of the molecule, which is completed by inversion symmetry. The cyclohexa-2,5-diene ring is exactly planar and reflects the bond-length distribution of a pair of located double bonds [1.3224 (14) Å] and two pairs of single bonds [1.5121 (13) and 1.5073 (14) Å]. The tetrahedral angle between the sp3-C atom and the two neighbouring sp2-C atoms in the cyclohexa-2,5-diene ring is enlarged by about 3°.

Propylene carbonate can be used as a green solvent for the asymmetric synthesis of cyanohydrin trimethylsilyl ethers from aldehydes and trimethylsilyl cyanide catalysed by VO(salen)NCS, though reactions are slower in this solvent than the corresponding reactions carried out in dichloromethane. A mechanistic study has been undertaken, comparing the catalytic activity of VO(salen)NCS in propylene carbonate and dichloromethane. Reactions in both solvents obey overall second-order kinetics, the rate of reaction being dependent on the concentration of both the aldehyde and trimethylsilyl cyanide. The order with respect to VO(salen)NCS was determined and found to decrease from 1.2 in dichloromethane to 1.0 in propylene carbonate, indicating that in propylene carbonate, VO(salen)NCS is present only as a mononuclear species, whereas in dichloromethane dinuclear species are present which have previously been shown to be responsible for most of the catalytic activity. Evidence from 51V NMR spectroscopy suggested that propylene carbonate coordinates to VO(salen)NCS, blocking the free coordination site, thus inhibiting its Lewis acidity and accounting for the reduction in catalytic activity. This explanation was further supported by a Hammett analysis study, which indicated that Lewis base catalysis made a much greater contribution to the overall catalytic activity of VO(salen)NCS in propylene carbonate than in dichloromethane.

An active nickel catalyst prepared in situ from a Ni(II) compound, phosphine ligand, and zinc powder was found to be an efficient catalyst system for the hydrocyanation of various alkenes using acetone cyanohydrin as a safer cyano source. The combination of NiCl 2 ·6H 2 O and 1,3-bis(diphenylphosphino)propane was the most efficient catalyst precursor in DMF. Under the optimized conditions, various styrenes, heterocyclic alkenes, and aliphatic alkenes were converted to their corresponding nitriles in excellent yields. [ABSTRACT FROM AUTHOR]

The absolute stereochemistry of cyanohydrins, derived from ketones and aldehydes, is obtained routinely, in a microscale and derivatization-free manner, upon their complexation with Zn-MAPOL, a zincated porphyrin host with a binding pocket comprised of a biphenol core. The host-guest complex leads to observable exciton-coupled circular dichroism (ECCD), the sign of which is easily correlated to the absolute stereochemistry of the bound cyanohydrin. A working model, based on the ECCD signal of cyanohydrins with known configuration, is proposed. [ABSTRACT FROM AUTHOR]

Hydroxynitrile lyases (HNLs) are increasingly finding application in synthesis of enantiomerically pure cyanohydrins. Cyanohydrins are important intermediates in the production of pharmaceuticals and agrochemicals. In the present studies seeds of wild apricot ( Prunus armeniaca L.) have emerged as potential source of hydroxynitrile lyase. The HNL of wild apricot (ParsHNL) was purified 8.1 fold and 18.2 % yield with a specific activity of 141 units mg protein. The SDS-PAGE of the enzyme revealed that it consists of subunits of 40 and 37 kDa. However, the molecular weight of holoenzyme was assessed to be 360 kDa. The enzyme showed maximum activity in 0.1 M sodium-citrate buffer having pH 4.75 at 25 °C. Thermostability studies revealed that this HNL showed activity up to 70 °C temperature and quite stable up to 50 °C. Activation energy of ParsHNL was calculated to be 37.83 kJ mol. This enzyme has K of 3.76 mM, V of 188.4 µmol mg min and k of 1130.4 s using mandelonitrile as substrate while for reverse reaction using benzaldehyde as substrate it showed K of 16.1 mM, V of 7.21 µmol mg min and k of 43.3 s. Synthesis of mandelonitrile was carried out using ParsHNL and finally 8.88 mmole (1.184 g) of mandelonitrile was recovered which corresponded to 89 % molar conversion with 96 % ee for R-mandelonitrile. The yield of mandelonitrile was 411 µmol mgh. These results indicated that ParsHNL has very high potential for synthesis of cyanohydrins and can be used for the production of enantiopure cyanohydrins. Graphical Abstract: [ABSTRACT FROM AUTHOR]

A convenient one-pot, two-step procedure for the synthesis of ketone cyanohydrin esters in aqueous media is reported using N -acylbenzotriazoles as the acylating agents. In saturated aqueous sodium bicarbonate containing a catalytic amount of tetrabutylammonium bromide, the reaction of ketones with potassium cyanide and N -acylbenzotriazoles proceeded readily at room temperature to provide the corresponding O -acyl cyanohydrin derivatives in good to excellent yields. [ABSTRACT FROM AUTHOR]

The insecticidal activities of several cyanohydrins, cyanohydrin esters and monoterpenoid esters (including three monoterpenoid esters of a cyanohydrin) were evaluated. Topical toxicity to Musca domestica L. adults was examined, and testing of many compounds at 100 mg/fly resulted in 100% mortality. Topical LD50 values of four compounds for M. domestica were calculated. Testing of many of the reported compounds to brine shrimp (Artemia franciscana Kellog) resulted in 100% mortality at 10 ppm, and two compounds caused 100% mortality at 1 ppm. Aquatic LC50 values were calculated for five compounds for larvae of the yellow fever mosquito (Aedes aegypti (L.)). Monoterpenoid esters were among the most toxic compounds tested in topical and aquatic bioassays.

The mechanism by which tertiary amines catalyse the formation of cyanohydrin carbonates from aldehydes and alkyl cyanoformates is investigated by means of a kinetic study. The reaction rate shows a second order dependence on amine concentration unless the amine is sterically hindered, when the rate has a first order dependence on amine concentration. The catalytic activity of the amine correlated with its p K aH . On the basis of these results, a mechanism is proposed in which the amine acts as a base to activate a water molecule, which reacts with the ethyl cyanoformate generating cyanide in situ. [ABSTRACT FROM AUTHOR]

Abstract: We report herein a new, sensitive and efficient method for detection, identification and quantification of cyanide in water samples. Cyanide was converted (>95% yield) to its versatile and stable derivative, 1-cyano-2,2,2-trifluoro-1-phenylethyl acetate (CTPA).The crude reaction mixture was directly subjected to high resolution fluorine-19 nuclear magnetic resonance (19F{1H} NMR) spectroscopy. In order to do away with signal overlap and dynamic range problems associated with 1H NMR spectroscopy, liquid chromatography with UV detection hyphenated to online solid phase extraction (LC–UV–SPE) was performed. The trapped and enriched CTPA was thereafter subjected to offline 1H NMR spectroscopy. In this way the δ 1H, δ 19F spectral signatures and LC–UV retention time were used for specific detection and identification and quantification of cyanide. The three techniques (viz. LC–UV and LC–UV–SPE followed by offline 1H NMR and 19F{1H} NMR spectroscopy) demonstrated good linearity (r 2 >0.99), reproducibility (inter-day RSD: 1.43–1.89%, 2.60–2.80%, 1.42–1.60; intra-day: RSD 1.20–1.38%, 3.21–3.25%, 1.00–1.19%), accuracy (recoveries: 95.1–97.2%, 77.5–82.8%, 96.8–98.9%) and LODs (1.31μg/mL, 4.24μg/mL, and 2.14μg/mL) respectively. Total time required for the analysis was ∼3h. Utility of the method was demonstrated by the detection and identification of spiked water samples. Since the derivative CTPA was volatile, could also be analyzed by GC–MS and GC–FTIR instruments. [Copyright &y& Elsevier]

Background and Aims A major germination-promoting chemical in smoke-water is 3-methyl-2H-furo[2,3-c]pyran-2-one (karrikinolide, KAR1). However, not all species that germinate in response to smoke-water are responsive to KAR1, such as Tersonia cyathiflora (Gyrostemonaceae). In this study, a test was made of whether two Gyrostemon species (Gyrostemonaceae) that have previously been shown to respond to smoke-water, respond to KAR1. If not, then the smoke-derived chemical that stimulates germination of these species is currently unknown. Recently, glyceronitrile was isolated from smoke-water and promoted the germination of certain Anigozanthos species (Haemodoraceae). Whether this chemical promotes Gyrostemon racemiger germination is also examined. Furthermore, an investigation was carried out into whether these species germinate in response to smoke-water derived from burning cellulose alone. Methods Gyrostemon racemiger and G. ramulosus seeds were buried after collection and retrieved in autumn the following year when dormancy was alleviated and seeds had become responsive to smoke-water. Anigozanthos flavidus seeds were after-ripened at 35 °C to alleviate dormancy. Gyrostemon and Anigozanthos seeds were then tested with ‘Seed Starter’ smoke-water, KAR1, glyceronitrile and cellulose-derived smoke-water. Key Results Although Gyrostemon racemiger, G. ramulosus and A. flavidus were all stimulated to germinate by ‘Seed Starter’ smoke-water, none of these species responded to KAR1. Gyrostemon racemiger germination was not promoted by glyceronitrile. This is in contrast to A. flavidus, where glyceronitrile, at concentrations of 1–500 µm, promoted germination, although seedling growth was inhibited at ≥400 µm. Maximum A. flavidus germination occurred at glyceronitrile concentrations of 25–300 µm. Some Gyrostemon germination was promoted by cellulose-derived smoke-water. Conclusions KAR1 and glyceronitrile, chemicals in smoke-water that are known to stimulate germination in other species, did not promote the germination of G. racemiger. This suggests that other chemical(s) which promote germination are present in smoke, and may be derived from burning cellulose alone. [ABSTRACT FROM AUTHOR]

Abstract: A resorcylic acid lactone (RAL) framework was constructed based on a three-component coupling approach. The key step was the intermolecular alkylation of a protected cyanohydrin with an aromatic scaffold, and the subsequent carbonylative esterification of the aryl iodide with an alcohol. This sequence allowed the rapid assembly of three components without extra protection/deprotection steps. This synthetic strategy enables the ketone at the 2′ position to be masked as a protected cyanohydrin during the ester formation, thus avoiding an undesired isocoumarin formation. This method should be widely applicable to the synthesis of various types of RAL frameworks. [Copyright &y& Elsevier]

Abstract: We describe efforts to achieve a multigram synthesis of the tricyclic spiroacetal core of the lituarines based on the addition of acyl anion equivalent to 4-(2-furyl)butan-2-one (18). We report the first cases of chemoselective Achmatowicz reaction in the presence of a second furan ring that lacks an α-hydroxyl group. The use of lithiated methoxyallene provides an efficient one-step conversion of ketone 18 into a tricyclic Diels–Alder adduct (27). In the final route, asymmetric cyanosilylation of ketone 29 achieved the construction of the stereogenic C(12) 3°-alcohol centre. Subsequent butenylation, diastereoselective reduction of keto-alcohol (+)-33 and alkene cross metathesis set up an oxy-Michael reaction to close the C(8–12) tetrahydropyran ring. The second ring-closure, which completed the route, was achieved by oxidative spirocyclisation following our earlier work. [Copyright &y& Elsevier]

O-Protected cyanohydrins were found to serve as a source of the nitrile within the intramolecular cobalt-mediated [2+2+2] cycloaddition to pyridines. Several 6-substituted 1,2,3,4,7,8,9,10-octahydrophenanthridines were synthesized using this cycloaddition of diyne-cyanohydrins. By introduction a TMS group a divergent way to such phenanthridine derivatives was elaborated. [ABSTRACT FROM AUTHOR]

Abstract: A kinetic analysis of the asymmetric addition of trimethylsilyl cyanide to benzaldehyde using three aluminium based catalysts has been carried out. All three catalysts displayed rate equations, which were first order in trimethylsilyl cyanide concentration and zero order in benzaldehyde concentration. The results are consistent with a common mechanism for effective asymmetric catalysis of cyanohydrin synthesis, involving combined activation of the aldehyde by a Lewis acid and activation of the trimethylsilyl cyanide by a Lewis base. The mechanistic analysis was also applied to a magnesium-based catalyst system to demonstrate its general applicability. [Copyright &y& Elsevier]

Abstract: Enzymatic kinetic resolution of a series of aromatic and aliphatic cyanohydrins in organic media has been investigated. The behavior of potential lipases, molecular sieves, acyl reagent, reaction temperature, and organic solvents on the kinetic resolution was studied. The influence of substrate structure, steric, and electronic nature and position of the aryl substituent on the enantioselectivity was discussed. Under the optimized reaction conditions, good enantioselectivity could be achieved for most of the investigated compounds. Specifically, substrates 1a, 1c, 1d, 1f, 1u could be resolved with the kinetic enantiomer ratio (E) higher than 200. [Copyright &y& Elsevier]

Abstract: The activity and enantioselectivity of several mutants of the esterase BS2 from Bacillus subtilis have been investigated. In the enzymatic hydrolysis of α,α-disubstituted cyanohydrin acetates, a class of tert. alcohol esters, they were active but not selective. In contrast to this result similar tert. acetylenic alcohol esters were hydrolysed with high E-values (>100). The difference in reactivity has been studied by molecular dynamics studies. The computer model suggested that the source of the observed difference in reactivity between the two very similar tert. alcohol esters lies in the ability of the cyanohydrins to form hydrogen bonds to water molecules—even when the substrate is in the active site. [Copyright &y& Elsevier]

The alkali salt of L-proline was demonstrated to be an efficient and practical catalyst for the cyanosilylation of a wide variety of simple and functionalized carbonyl compounds under solvent-free conditions. The reactions proceeded smoothly at room temperature to afford the corresponding cyanohydrins in good to excellent yields. [ABSTRACT FROM AUTHOR]

Overexpression and production of the high concentration of hydroxynitrile lyase from cassava ( Manihot esculenta (MeHNL, EC 4.1.2.39)) were investigated. Hydroxynitrile lyase is a useful enzyme for the production of optically active cyanohydrin compounds. The production of MeHNL was increased by changing the rare codons of the original sequence of cassava MeHNL. However, most of the produced MeHNL was in the insoluble form. In order to increase the solubility of MeHNL, the effects of the cultivation temperature were investigated. When the cultivation temperature was reduced, the cell yield and the ratio of soluble MeHNL increased significantly. The enzyme activity and yield at low-temperature cultures (17 °C) were 850 times higher than those obtained at the optimum growth temperature of 37 °C. The rate of MeHNL production in the present study was calculated as 3,000 unit/h. Low-temperature cultivation was very effective in improving the productivity of the active form of MeHNL. Unlike the temperature-shift method, low-temperature cultivation has more potential for the large-scale production of MeHNL for the optically active cyanohydrin production. [ABSTRACT FROM AUTHOR]

The article reports on the expression of hydroxynitrile lyase from Manihot esculenta (MeHNL) in yeast and its application in (S)-Mandelonitrile production using an immobilized enzyme reactor. It states that MeHNL was cloned from a cDNA library prepared from a leaf of MeHNL which is then expressed in a multi-auxotrophic mutant of Saccaromyces cerevisiae cells. The author adds that Silica gel was the most appropriate support for immobilization of the prepared enzyme from the recombinant yeast.

Abstract: The application of (R)-hydroxynitrile lyases ((R)-HNLs) enables a simple chemo-enzymatic approach towards (R)-pantolactone synthesis. For the first time, several new recombinant almond (R)-HNL isoenzymes were compared with native HNLs from different Prunus species with respect to cyanohydrin formation from hydroxypivalaldehyde providing the chiral key precursor in HNL based (R)-pantolactone synthesis. Recombinant PaHNL5 (R-selective hydroxynitrile lyase, isoenzyme 5, from Prunus amygdalus) surpasses all other tested natural and recombinant HNL variants. At low pH even very low amounts of crude enzyme catalysed stereoselective hydroxypivalaldehyde cyanohydrin formation in water based reaction systems. [Copyright &y& Elsevier]

Abstract: Synthetically useful cyanohydrin acetates, ArCH(OAc)CN (Ar=C6H5, 3,4-methylenedioxyphenyl, 4-Me–C6H4, 4-Cl–C6H4, 4-F–C6H4, 4-CF3–C6H4), were successfully synthesized in high enantiomeric purities (79–93% ee) via the lipase-catalyzed dynamic kinetic resolution (DKR) of cyanohydrins synthesized in situ from the corresponding aldehydes and acetone cyanohydrin. The combined use of silica-supported BTAH (benzyltrimethylammonium hydroxide) and porous ceramic-immobilized lipase under the optimized reaction conditions enabled the remarkable acceleration of the enantioselective DKR reactions. [Copyright &y& Elsevier]

Abstract: Basic ammonium salts act as highly effective catalysts for the cyanosilylation of aldehydes and in Strecker-type aminonitrile synthesis using TMSCN as cyanide source at 25°C under extremely mild conditions, affording very good to excellent yields of silylated cyanohydrins and α-aminonitriles. [Copyright &y& Elsevier]

Abstract: A new and general synthesis of alkyl cyanoformates is presented starting from the appropriate alcohol and oxalyl chloride. This is used to prepare enantiomerically pure cyanoformates from enantiomerically pure primary and secondary alcohols. Optimal conditions for the addition of various achiral cyanoformates to aldehydes catalysed by an enantiomerically pure titanium(salen) catalyst in the presence of potassium cyanide as a cocatalyst are developed. Under these conditions, two chiral cyanoformates also reacted with aldehydes to give cyanohydrin carbonates. The stereochemistry of this process is predominantly determined by the stereochemistry of the titanium(salen) catalyst and the stereochemistry of two of the cyanohydrin carbonates was confirmed by X-ray crystallography. In a further extension of the chemistry, a homogeneous system in which the potassium cyanide/18-crown-6 complex is used as the cyanide cocatalyst has been developed and the kinetics of this reaction show that it displays first order kinetics, provided at least 2mol% of the potassium cyanide complex are employed. [Copyright &y& Elsevier]

Abstract: Titanium(IV)(salen) and vanadium(V)(salen) complexes are both known to form catalysts for asymmetric cyanohydrin synthesis. When a mixture of titanium and vanadium complexes derived from the same or different salen ligands is used for the asymmetric addition of trimethylsilyl cyanide to benzaldehyde, the absolute configuration of the product and level of asymmetric induction can only be explained by in situ formation of a catalytically active heterobimetallic complex, and is not consistent with two monometallic species acting cooperatively. Combined use of complexes containing chiral and achiral salen ligands demonstrates that during the asymmetry inducing step of the mechanism, the aldehyde is coordinated to the vanadium rather than the titanium ion. The titanium complexes also catalyse the asymmetric addition of ethyl cyanoformate to aldehydes, a reaction in which vanadium(V)(salen) complexes are not active. For this reaction, use of a mixture of titanium and vanadium(salen) complexes results in a complete loss of catalytic activity, a result which again can only be explained by in situ formation of a heterometallic complex. Both the titanium and vanadium based catalysts also induce the asymmetric addition of potassium cyanide/acetic anhydride to aldehydes. For this reaction, combined use of chiral and achiral complexes indicates that during the asymmetry inducing step of the mechanism, the aldehyde is coordinated to titanium rather than vanadium, a result which contrasts with the observed results when trimethylsilyl cyanide is used as the cyanide source. [Copyright &y& Elsevier]

The defatted seed meal of common vetch ( Vicia sativa L.) served as a source of ( R)-oxynitrilase which catalyzed the enantioselective addition of HCN to aromatic, heteroaromatic, fluoro-substituted aromatic aldehydes to produce the corresponding enantiomeric pure cyanohydrins in yields of 52–100% and 88–99% ee at 12°C under micro-aqueous medium (diisopropyl ether) without addition of buffer solution. [ABSTRACT FROM AUTHOR]

Benzil (1,2-diphenylethane-1,2-dione) undergoes cyanide catalyzed condensation with benzaldehyde to yield O-benzoylated benzoin (2-benzoyl-1,2-diphenylethanone). In this study, the experimentally suggested mechanism has been modeled with PM3 and verified with B3LYP. The effect of the substituent on the reaction yield has been rationalized by considering two benzil derivatives; 1,2-bis(2-chlorophenyl)ethane-1,2-dione and 1,2-bis(2-fluorophenyl)ethane-1,2-dione and three benzaldehyde derivatives; o-fluorobenzaldehyde, o-methylbenzaldehyde and 2-pyridinecarboxaldehyde. The effect of the solvent has been modeled by using the isodensity-surface polarizable continuum (IPCM) model. Reactivity descriptors have been used to justify the reactivity differences of the various substituents. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [ABSTRACT FROM AUTHOR]

Abstract: N-Heterocyclic carbenes produced in situ from salts of imidazolium, benzimidazolium, pyrido[1,2-c]imidazolium, imidazolinium, thiazolium, and triazolium catalyze the addition of trimethylsilylcyanide to aldehydes to yield cyanohydrin trimethylsilyl ethers. The use of C 2-symmetric imidazolidenyl carbene derived from (R,R)-1,3-bis[(1-naphthyl)ethyl]imidazolium chloride led to enantioselective cyanosilylation. [Copyright &y& Elsevier]

Abstract: Trimethylsilyl cyanide asymmetrically adds to various ketones by catalysis of 1 /triphenylphosphine oxide. This is a double activation where 1 acts as Lewis acid and Ph3PO Lewis base. Various ketones were subjected to the enantioselective addition so as to give up to 92% ee and >90% yield. [Copyright &y& Elsevier]

Abstract: The 1,2-addition of trialkylsilylcyanides to aldehydes and ketones produces the corresponding protected cyanohydrins in good to excellent yields when carried out at 0°C to room temperature in the presence of catalytic amounts of the nonionic strong base P(RNCH2CH2)N (R=Me, i-Pr) in THF. These catalysts are easily removed from the product by hydrolysis or column filtration through silica gel. [Copyright &y& Elsevier]

Abstract: A bimetallic titanium(salen) complex has been used to catalyze the asymmetric addition of potassium cyanide to aldehydes attached to Wang resin giving polymer supported cyanohydrin propionates with up to 91% enantiomeric excesses. [Copyright &y& Elsevier]