Search

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]

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]

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]

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]

Nitrile/cyanide hydrolysis is of importance from the perspective of organic chemistry, especially, prebiotic chemistry. Herein we report that cyanohydrins, generated by the reaction of cyanide with β-keto acids and γ-keto-alcohols, spontaneously hydrolyze under ambient conditions (aqueous medium, RT, and a range of pH). The spontaneous hydrolysis is affected by an intramolecular proton transfer and an intramolecular 5- exo-dig attack, but with a twist. In the case of β-keto acids, the hydrolysis is mediated by the neighboring carboxylic acid group only at pH values less than 7, whereas in the case of γ-keto-alcohols the hydrolysis is mediated by the neighboring hydroxyl group only at pH values greater than 7. The results, in combination with previous works, have implications for selective transformations of cyanide-initiated prebiotic systems chemistry. [ABSTRACT FROM AUTHOR]

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 article presents a study to describe an efficient protocol for the conjugate addition of cyanide to alpha, beta-unsaturated ketones 1a-j using trimethylsilyl cyanide (TMSCN) as cyanide source and Amb-F as solid catalyst under solvent-free conditions (SolFC). It discusses the addition of TMSCN to (E)-hept-3-en-2-one (1a). The study suggests that an initial 1,2-addition of cyanide to the a,b-unsaturated ketone 1 occurs giving the cyanohydrin trimethylsilyl ether 2.

Synchronous metabolic oscillations can be induced in yeast by addition of glucose and removal of extracellular acetaldehyde (ACA x ). Compared to other means of ACA x removal, cyanide robustly induces oscillations, indicating additional cyanide reactions besides ACA to lactonitrile conversion. Here, 13 C NMR is used to confirm our previous hypothesis, that cyanide directly affects glycolytic fluxes through reaction with carbonyl-containing compounds. Intracellularly, at least 3 cyanohydrins were identified. Extracellularly, all signals could be identified and lactonitrile was found to account for ~66% of total cyanide removal. Simulations of our updated computational model show that intracellular cyanide reactions increase the amplitude of oscillations and that cyanide addition lowers [ACA] instantaneously. We conclude that cyanide provides the following means of inducing global oscillations: a) by reducing [ACA x ] relative to oscillation amplitude, b) by targeting multiple intracellular carbonyl compounds during fermentation, and c) by acting as a phase resetting stimulus. [ABSTRACT FROM AUTHOR]

A direct synthetic method for cyanohydrin esters from aroyl chlorides using potassium hexacyanoferrate(II) as an eco-friendly cyanide source and tributylphosphine as a promoter is described. This protocol has advantages of no use of strong toxic cyanating agents, high yield, and simple work-up procedure. [ABSTRACT FROM AUTHOR]

Reactions of 3-oxo derivatives of cholic acid esters with acetone cyanohydrin and trimethylsilyl cyanide lead to exclusive or predominant formation of the corresponding 3-cyano-3-hydroxy and 3-cyano-3-trimethylsiloxy derivatives with axial orientation of the cyano group. Reduction of the cyano group in the addition products gives 3-aminomethyl derivatives which can be used to obtain pincer ligands containing two cholane fragments. [ABSTRACT FROM AUTHOR]

Four ruthenium(II) complexes, [Ru(bpy)2L1](PF6)2, [Ru(bpy)2L2](PF6)2, [Ru(dmb)2L1](PF6)2, and [Ru(dmb)2L2](PF6)2, where bpy = 2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, L1 = 4-methyl-2,2'-bipyridine-4'-carboxaldehyde, and L2 = 4,4'-diformyl-2,2'-bipyridine, have been characterized for sensing cyanide based on the well-known formation of cyanohydrins. The structure of [Ru(dmb)2L2](PF6)2 is also determined by single crystal X-ray diffraction. Their cyanide anion binding properties in pure and aqueous acetonitrile solution were thoroughly examined by UV-Vis absorption and photoluminescence (PL) spectroscopy. Upon the addition of cyanide to the solution of ruthenium(II) complexes at 298 K, a color change from orange to yellow and a luminescent variation from dark red to red-orange can be observed by the naked eye. The large blue shift of the absorption and emission spectra and significant enhancement of the emission intensity upon the addition of cyanide could be attributed to the formation of a cyanohydrin group by the selective reaction of the aldehyde group of the ruthenium(II) complexes with cyanide. Importantly, these kinds of ruthenium(II) complexes show a unique recognition of cyanide ions over other anions. The results reveal that this kind of ruthenium(II) complex containing an aldehyde group is an eligible sensor for cyanide anions. [ABSTRACT FROM AUTHOR]

Hydroxynitrile lyase from cassava, Manihot esculenta, ( MeHNL) catalyzes the formation of ( S)-cyanohydrins from HCN and aldehydes or ketones. Four differently immobilized MeHNLs were prepared: by noncovalent immobilization (celite R-633), covalent immobilization (cross-linked enzyme aggregates, CLEA), encapsulation [in a poly(vinyl alcohol) hydrogel Lentikats] and a combination of the above, an unusual immobilization, CLEA encapsulated in a poly(vinyl alcohol) hydrogel. A comparative study of the recyclability of each immobilized MeHNL was performed. Particular attention was paid to the stability and activity of the new immobilized MeHNL-CLEA-Lentikats and to the minimum enzyme loading required to achieve high yields and enantiomeric excesses. MeHNL-CLEA stability was slightly improved by encapsulation into Lentikats and good recyclability rates at low enzyme loading were obtained. However, MeHNL immobilized on celite R-633 exhibited the best recyclability, giving >95 % conversion and an enantiomeric excess of 99 % during 12 cycles. [ABSTRACT FROM AUTHOR]

Masked acyl cyanide (MAC) reagents are shown to be effective umpolung synthons for enantioselective Michael addition to substituted enones. The reactions are catalyzed by chiral squaramides and afford adducts in high yields (90-99%) and with excellent enantioselectivities (85-98%). The addition products are unmasked to produce dicyanohydrins that, upon treatment with a variety of nucleophiles, provide γ-keto acids, esters, and amides. The use of this umpolung synthon has enabled, in enantiomerically enriched form, the first total synthesis of the prenylated phenol (+)-fornicin C. [ABSTRACT FROM AUTHOR]

Abstract: Cyanation-O-protection reaction of ketones with different cyanide sources catalyzed by N-heterocyclic carbenes is reported. Under the catalysis of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, various ketones coupled with diethyl cyanophosphonate to produce cyanohydrin-O-phosphates with a quaternary carbon center in moderate to excellent yield. Furthermore, the reaction can be scaled-up easily and high yield maintained. [Copyright &y& Elsevier]

Chiral keto nitriles (β-cyano ketones) have been prepared by a facile and efficient asymmetric conjugate hydrocyanation of poorly active chalcone-type enones with benzophenone cyanohydrin. Using in situ generated 5-10 mol-% of sodium ( S)-6,6′-di(1-adamantyl)-1,1′-binaphthyl-2,2′-diyl phosphate as catalyst and 5-10 mol-% of 2- tert-butylphenol as an additive, high yields and excellent enantioselectivities were obtained within 2 h in toluene at 80 °C. The development of catalysts, optimization of the reaction parameters, and substrate scope are reported. On the basis of the experimental results, HCN is shown to be the real cyanide source and a mechanism is proposed to explain the origin of the enantioselectivity with the chiral-anion-modified nucleophile HCN. [ABSTRACT FROM AUTHOR]

O-(α-Bromoacyl) cyanohydrins were prepared in a single step from a range of different aldehydes in combination with α-bromoacyl cyanides. By the use of a cyclic procedure where the two minor diastereoisomers from a chiral Lewis acid-catalyzed reaction undergo Candida antarctica lipase B (CALB)-catalyzed hydrolysis followed by dehydrocyanation to regenerate the starting material, the products were obtained in good to high yields and in most cases with excellent diastereoselectivites. The synthetic importance of these compounds was demonstrated by the synthesis of 4-amino-2(5H)-furanones, a class of compounds that have shown both biological activity and utility as synthetic intermediates. This transformation was achieved by an intramolecular Blaise reaction, which gave the products in high to excellent yields and enantiomeric ratios. [ABSTRACT FROM AUTHOR]

Highlights: [•] A method for the analysis of the cyanide detoxification product, α-KgCN, was developed. [•] The method produced a linear range of 0.3–50μM α-KgCN in swine plasma. [•] The method was successful at detecting α-KgCN in cyanide-exposed swine. [•] The method allows for confirmation of cyanide exposure by analysis of α-KgCN. [ABSTRACT FROM AUTHOR]

This paper describes the solvent-assisted addition of trimethylsilyl cyanide (TMSCN) to cyclic α-fluorinated ketones. In DMF, this method gives TMS-protected cyanohydrins in good yields (70-95 %) and with good selectivities ( dr up to 22:1), and the products are readily reduced to the corresponding fluorinated 1,2-amino alcohols. [ABSTRACT FROM AUTHOR]

Chiral macrocyclic TiIV-salen complexes were used as efficient catalysts in the asymmetric cyanoethoxy carbonylation of aldehydes. The TiIV catalysts demonstrated excellent performance (product yields and ee values up to 99 %) with ethyl cyanoformate as the cyanide source and a catalyst loading of 0.5 mol %, which is the lowest known. The macrocyclic TiIV-salen complex retained its performance at multigram level and was conveniently recycled for a number of times. The product obtained was straightforwardly transformed to the pharmaceutically important chiral drugs ( R)-proethalol (β-blocker) and ( R)-phenylephrine (α1-adrenergic receptor agonist) in good yields. To understand the mechanism of the catalytic reaction, a kinetic investigation was conducted with various concentrations of the catalyst, ethyl cyanoformate and benzaldehyde as the representative substrate. The reaction of benzaldehyde was first order with respect to the concentration of the catalyst and the ethyl cyanoformate but did not depend on the initial concentration of the substrate. A possible mechanism of the cyano-ethoxy carbonylation reaction was proposed. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of 7-aminoacetylindoles was achieved via the hydrogenation of 7-acylcyanides, which were produced through the oxidation of indole-7-cyanohydrin silylether intermediates. 7-Oxotryptamines were subsequently converted into 5-(7′-indolyl)oxazoles by reaction with acetic anhydride followed by phosphoryl chloride, and to 2,5-di-(7′-indolyl)oxazoles by reaction with 7-trichloroacetylindoles followed by phosphoryl chloride. [Copyright &y& Elsevier]

A series of β-hydroxynitriles were efficiently synthesized from the regioselective ring opening of oxiranes by cyanide anion in the presence of silica-bound 3-{2-[poly(ethylene glycol)]ethyl}-substituted 1-methyl-1 H-imidazol-3-ium bromide (SiO2PEGImBr) as a novel recoverable phase-transfer catalyst in H2O ( Scheme 1 and Table 2). The workup procedure was straightforward, and the catalyst could be reused over four times with almost no loss of catalytic activity and selectivity. [ABSTRACT FROM AUTHOR]

It is well known that burning of vegetation stimulates new plant growth and landscape regeneration. The discovery that char and smoke from such fires promote seed germination in many species indicates the presence of chemical stimulants. Nitrogen oxides stimulate seed germination, but their importance in post-fire germination has been questioned. Cyanohydrins have been recently identified in aqueous smoke solutions and shown to stimulate germination of some species through the slow release of cyanide. However, the most information is available for karrikins, a family of butenolides related to 3-methyl-2 H-furo[2,3- c]pyran-2-one. Karrikins stimulate seed germination and influence seedling growth. They are active in species not normally associated with fire, and in Arabidopsis they require the F-box protein MAX2, which also controls responses to strigolactone hormones. We hypothesize that chemical similarity between karrikins and strigolactones provided the opportunity for plants to employ a common signal transduction pathway to respond to both types of compound, while tailoring specific developmental responses to these distinct environmental signals. [ABSTRACT FROM AUTHOR]

Abstract: A dimeric salen ligand derived from L-tartaric acid was synthesized through linking two salen units with 1,6-dibromohexane. The corresponding Ti complex was proved to be an efficient catalyst for asymmetric addition of trimethylsilyl cyanide to aldehydes, providing the corresponding optically active trimethylsilyl ether of cyanohydrins with moderate to good enantiomeric excesses and excellent yields under relatively low catalyst loading condition. [Copyright &y& Elsevier]

Abstract: Cassava contains cyanogenic glucosides which are hydrolysed by an enzyme linamarase to produce cyanohydrins which breakdown to toxic cyanide. Cyanide ingestion from bitter cassava can cause cyanide poisoning sometimes leading to death and also konzo, an irreversible paralysis of the legs which occurs mainly in children and young women. In 2005 we developed a simple wetting method that reduces the total cyanide content of cassava flour 3–6-fold. It involves wetting the flour, spreading it in a thin layer in the shade for 5h and using it the same day to make traditional thick porridge (ugali). The method was readily accepted by rural women and requires no additional equipment or water. Laminated, illustrated posters describing the method are available for free in ten languages, see http://online.anu.edu.au/BoZo/CCDN/. An equally effective treatment method is to expose wet flour in a thin layer in the sun for 2h. Projects for rehabilitation and prevention of konzo occurred in Mozambique in 2007 and in 2008–2009 in Tanzania, funded by AusAID. The Ministry of Health in Mozambique is now using our posters in Macua. In Uvira DRC, the wetting method has been taught in many villages and over 1200 posters distributed. [Copyright &y& Elsevier]

Abstract: Epoxides can be opened under neutral conditions with TMSN3 and TMSCN in the presence of catalytic amounts of Lewis acid, affording the corresponding ring-opened compounds in high yields. [ABSTRACT FROM AUTHOR]

Aliphatic azidonitriles separated by three or four carbon atoms undergo facile cyclo additions in the presence of BF3∙OEt2 at room temperature or lower, to give bicyclic tetrazoles. 1-Azido-[2-aryl-1,3-dioxolanyl]-glycerols afford oxabicyclic tetrazoles with trimethylsilyl cyanide (TMSCN). Aspects of these facile proximity-induced 1,3-dipolar cyclo additions are discussed with mechanistic interpretations. [ABSTRACT FROM AUTHOR]

Abstract: In 2005 a simple wetting method was developed that reduced total cyanide content of cassava flour 3–6-fold. The method involved spreading wet flour in a thin layer and standing in the shade for five hours to allow evolution of HCN gas. We found that breakdown of linamarin catalysed by linamarase to acetone cyanohydrin, followed by its spontaneous decomposition to HCN and acetone was greatly increased by standing the wet flour in the sun. Treatment for two hours in the sun gave the same amount of total cyanide remaining as five hours in the shade. This rapid treatment in the sun may be more acceptable to rural women in Democratic Republic of Congo, than five hours in the shade. The two methods are offered as alternatives for use in rural Africa. With adequate linamarase present the residual cyanogen remaining after the wetting treatment was acetone cyanohydrin. [Copyright &y& Elsevier]

A versatile synthesis of enantiomerically pure cis- and trans-2,5-disubstituted morpholines is described. Hydroxynitrile lyase-mediated cyanide addition onto aldehydes provided cyanohydrins in virtually quantitative yield and excellent enantioselectivity. Subsequent formation of diastereomerically pure amino esters via a three-step, one-pot reduction-transimination-reduction sequence followed by reduction and simultaneous protection provided cyclization precursors. Finally, cyclization and SmI,-mediated reductive detosylation completed the synthesis of cis- and trans-2,5-disubstituted morpholines in good yields and excellent diastereoselectivities. [ABSTRACT FROM AUTHOR]

The addition of acyl cyanides to prochiral aldehydes catalyzed by a chiral Lewis acid and an achiral Lewis base produces highly enantioenriched O-acylated cyanohydrins. ?-Keto esters undergo the same type of addition, although via a different mechanism in which the enantioselectivity originates from a chiral Lewis base. In the presence of a biocatalyst, the minor, undesired enantiomer obtained in the reactions with aldehydes can be selectively hydrolyzed to re-form the starting aldehyde, permitting the reaction to be run in a cyclic manner. The minor-enantiomer recycling results in an essentially enantiopure product. Selective enzymatic hydrolysis is also a key step in high-throughput analysis of conversions and enantiomeric ratios. 1 Introduction 2 Cyanide Sources 3 Enantioselective Acylcyanation of Aldehydes 3.1 Dual Lewis Acid-Lewis Base Activation 3.2 Synthesis of a Herbicide Intermediate 3.3 Mechanistic Aspects 4 Minor-Enantiomer Recycling 5 Enantioselective Addition of Acyl Cyanides to Ketones 5.1 Chiral Lewis Base Catalyzed Addition of Acetyl Cyanide to ?-Keto Esters 5.2 Mechanistic Aspects 6 High-Throughput Synthesis and Analysis of O-Acylated Cyanohydrins 6.1 Determination of Enantiomeric Excess 7 Conclusions [ABSTRACT FROM AUTHOR]

Abstract: This Letter describes a novel synthetic approach towards imidazo[1,2-a]pyridines via a three-component condensation using trimethylsilyl cyanide (TMSCN) or cyanohydrins as the source of CN− ions and silica-sulfuric acid as the catalyst. [Copyright &y& Elsevier]

Cyanide ion catalyzed addition of acylphosphonates to diethyl cyanophosphonate furnished phosphonocyanohydrin O-phosphates in high yield. The reaction works via the phosphonate-phosphate rearrangement, followed by the addition of diethyl ?cyanophosphonate to the cyanohydrin phosphate anion. [ABSTRACT FROM AUTHOR]

Abstract: Potassium phthalimide was found to be a highly effective and easily accessible organocatalyst for the cyanosilylation of various carbonyl compounds under extremely mild conditions. The corresponding cyanohydrin trimethylsilyl ethers were obtained in high to quantitative yields in solvent-free conditions at room temperature using 2.5mol% catalyst loading. [Copyright &y& Elsevier]

Abstract: The sensitivity of the normal picrate method for determination of total cyanide in cassava was increased tenfold using a small 1cm2 picrate paper, eluted using 0.5mL instead of 5mL of water as in the normal method. The absorbance was measured in a 2mm cuvette in the spectrophotometer. The sensitive method was calibrated against the normal picrate method. The total cyanide content in mg HCN equivalents/kg sample = ppm, is calculated from the absorbance (A) by the equation ppm = A×45.7 which is applicable from 0.1 to 50ppm. A new method to determine acetone cyanohydrin was developed based on irreversible denaturation of linamarase in 0.1M HCl at 30°C for 1h. Five gari samples from Mozambique gave a mean total cyanide content of 12ppm (range 6–15ppm) and mean acetone cyanohydrin content of 11ppm (range 5–14ppm). Acetone cyanohydrin liberates cyanide quantitatively in the human intestine. [Copyright &y& Elsevier]

Abstract: Cyanide is a rapidly acting mitochondrial poison that inhibits cellular respiration and energy metabolism leading to histotoxic hypoxia followed by cell death. Cyanide is predominantly a neurotoxin but its toxic manifestations in non-neuronal cells are also documented. This study addresses the oxidative stress mediated cytotoxicity of cyanide in Rhesus monkey kidney epithelial cells (LLC-MK2). Cells were treated with various concentrations of potassium cyanide (KCN) for different time intervals and cytotoxicity was evidenced by increased leakage of intracellular lactate dehydrogenase, mitochondrial dysfunction (MTT assay) and depleted energy status of cells (ATP assay). Cytotoxicity was accompanied by lipid peroxidation indicated by elevated levels of malondialdehyde (MDA), reactive oxygen species (ROS) and reactive nitrogen species (RNS) (DCF-DA staining), diminished cellular antioxidant status (reduced glutathione (GSH), glutathione peroxidase, superoxide dismutase and catalase). These cascading events triggered an apoptotic kind of cell death characterized by oligonucleosomal DNA fragmentation and nuclear fragmentation (Hoechst 33342 staining). Apoptosis was further confirmed by increased caspase-3 activity. Cyanide-induced cytotoxicity, oxidative stress, and DNA fragmentation were prevented by alpha-ketoglutarate (A-KG) and N-acetyl cysteine (NAC). A-KG is a potential cyanide antidote that confers protection by interacting with cyanide to form cyanohydrin complex while NAC is a free radical scavenger and enhances the cellular GSH levels. The study reveals cytotoxicity of cyanide in cells of renal origin and the protective efficacy of A-KG and NAC. [Copyright &y& Elsevier]

High-yielding cyanosilylation of ketones with NaCN and various chlorotrialkylsilanes in DMSO proceeds smoothly without catalysis to give silyl-protected ketone cyanohydrins. The unique role of DMSO consists in rendering naked cyanide anions that reversibly add to the C=O bond at the rate-determining step followed by fast trapping of the transient tertiary sodium cyanoalcoholates with chlorotrialkylsilanes or in situ generated cyanotrialkylsilanes. Preparatively, the reaction matches the best known catalytic cyanosilylation systems applying expensive Me3SiCN and demonstrates unprecedented efficiency in the synthesis of sterically congested trialkylsilyl-protected cyanohydrins. [ABSTRACT FROM AUTHOR]

Focuses on the development and potential of asymmetric catalysts for cyanohydrin synthesis. Advantages of chiral cyanohydrins, including the preparation of anticlotting agent clopidogrel; Limitations of combining ligands and Lewis acid metals as chiral catalysts; Suitability of sodium or potassium cyanide as the cyanide source of the synthesis.

Enzymatic crude preparations obtained from a variety of food plants were screened for hydroxynitrile lyase activity. The results show that crude material from the seeds of the fruits quince, melon, anona and cherimoya as well as the material from the leaves of plum, peach, cherry and mamey biocatalyze the addition of hydrogen cyanide (HCN) to benzaldehyde with good to excellent enantioselectivities. [Copyright &y& Elsevier]

An efficient method of addition of trimethylsilylcyanide to ketones by employing cesium fluoride as catalyst has been described. A variety of aromatic, aliphatic, cyclic and heterocyclic ketones have been converted into their corresponding trimethylsilyl ethers in excellent yield. [Copyright &y& Elsevier]

The reaction of spiroepoxycyclohexadienones 1 with TMSCN in the presence of catalytic amounts of Bu4NCN results in the formation of two diastereomeric cyanohydrins. Alternatively, the reaction of 1 with equimolecular amounts of Bu4NCN gave rise to products arising from two other different reaction paths. [Copyright &y& Elsevier]

Labeled glycerol is a widely used biochemical probe to investigate biosynthetic pathways. A highly efficient synthesis of [1-13C, 18O]- and [1-13C, 2H2]-glycerol is described in which the 13C label is introduced using cyanide. The 18O label was introduced by a Pinner synthesis and reduction of the ester 5 allowed incorporation of the 2H labels. [Copyright &y& Elsevier]

A new “turn-on” luminescence probe for imaging the uptake of 0.2 ppm inorganic CN− in live HeLa cells as well as for probing the CN− generation through an enzymatic process in a virtual aqueous medium at appropriate pH. [ABSTRACT FROM AUTHOR]

Room-temperature synthesis of enantioenriched non-protected cyanohydrins using acetone cyanohydrin as the cyanide source was achieved by V(salalen) catalyst. Aliphatic aldehydes underwent the cyanation with 89–95% ee in the presence of only 0.2–0.4 mol% catalyst. Aromatic cyanohydrins were also obtained in high enantiomeric excesses under modified conditions. [ABSTRACT FROM AUTHOR]

During asymmetric cyanohydrin synthesis catalysed by vanadiumVoxo(salen) complexes, the catalysts are reduced to vanadiumIVoxo(salen) as determined by EPR spectroscopy; the reducing agent is cyanide which is oxidised to cyanogen viaa non-radical mechanism. [ABSTRACT FROM AUTHOR]

Several cyanohydrins were synthesized by the reaction of trimethylsilyl cyanide with carbonyl compounds in the presence of solid lithium perchlorate in high yields under solvent-free conditions. [Copyright &y& Elsevier]

The article discusses the synthesis and different usage of trimethylsilyl cyanide (TMSCN), a commercial reagent used as cyanide source for nucleophilic reactions. A description of the agent is offered. It states that TMSCN is generally used in nucleophilic additions to aldehydes, ketones and imines to form cyanohydrin silyl ethers2 and α-aminonitriles3 in Strecker-type reactions.

The article presents abstracts on topics related to the cyanide compound trimethylsilyl cyanide (TMSCN) which include TMSCN's addition to carbonyl compounds, the synthesis of acylferrocenes' cyanohydrin trimethylsilyl ethers through the addition of TMSCN, and the production of selective cyanation products through the addition of TMSCN to electron-rich heteroaromatic compounds.

The article discusses the use of high-throughput enzymatic method for enantiomeric excess determination of O-acetylated cyanohydrins. New catalysts for asymmetric synthesis can be discovered using high-throughput methods. Lack of general techniques for efficient enantiomeric excess determinations has been a major constraint in developing parallel screening methods for assessing catalyst performance. Highly enantioenriched O-acetylated cyanohydrins have been prepared from aldehydes and acetyl cyanide using a highly efficient catalytic system.

A variety of cyanohydrin alkyl ethers were readily prepared from aldehydes with trimethylsilyl cyanide and alkoxy-trimethylsilane under the influence of a catalytic amount of iron(III) chloride in a convenient one-pot procedure. [ABSTRACT FROM AUTHOR]

The enantioselective synthesis of cyanohydrins from aldehydes and ketones represents a useful avenue for the synthesis of important organic intermediates, for example, a-hydroxy acids and their derivatives and β-amino alcohols. For this reason there has been intense research activity in this area in recent years, leading to the development of a large and diverse array of chiral catalysts. In this article authors describes a new chiral catalyst system that is based on boron and the recognition of a novel cyanide donor. A variety of aldehydes, aromatic and aliphatic, have been transformed into cyanohydrins with greater than 90% enantiomeric purity under standardized conditions. The chiral precursor of the catalyst is readily recoverable. Finally, the absolute stereochemical course of the reaction is predicted clearly by a well-precedented mechanism.