Showing papers on "Benzaldehyde published in 1992"
TL;DR: The complex of titanium ethoxide and an acyclic dipeptide ester whose terminal amino group is modified to a salicylal-type Schiff base catalyzes the asymmetric addition of hydrogen cyanide to aldehydes with high enantioselectivity as discussed by the authors.
Abstract: The complex of titanium ethoxide and an acyclic dipeptide ester whose terminal amino group is modified to a salicylal-type Schiff base catalyzes the asymmetric addition of hydrogen cyanide to aldehydes with high enantioselectivity. In the reaction of benzaldehyde and hydrogen cyanide, (R)-mandelonitrile is obtained with an enantiomeric excess of 90% when N-((2-hydroxy-1-naphthyl)methylene)-(S)-valyl-(S)-tryptophan methyl esteris employed
124 citations
TL;DR: Cytochrome P450 cam oxidizes styrene to styrene oxide and a trace of phenylacetaldehyde; cis-β-methylstyrene to cis- β-methylstylrene oxide, cis-3-phenyl-2-propen-1-ol, and a traces of 1phenyl 2-propanone.
Abstract: Cytochrome P450 cam oxidizes styrene to styrene oxide and a trace of phenylacetaldehyde; cis-β-methylstyrene to cis-β-methylstyrene oxide, cis-3-phenyl-2-propen-1-ol, and a trace of 1-phenyl-2-propanone; and trans-β-methylstyrene to trans-β-methylstyrene oxide, trans-3-phenyl-2-propen-1-ol, and a trace of 1-phenyl-2-propanone. Aromatic ring hydroxylation is also observed as a very minor process with each of the three substrates. Benzaldehyde is formed as a major product in all the reactions, but its formation is due to oxidation of the olefins by the H 2 O 2 produced by uncoupled turnover of the enzyme
104 citations
TL;DR: In this paper, reactions of organic oxygen compounds, such as terbutanol, benzyl alcohol, dibenzylether and benzaldehyde, with silicon halides provide a novel non-hydrolytic sol-gel route to silica.
Abstract: Reactions of organic oxygen compounds, such as ter-butanol, benzylalcohol, dibenzylether and benzaldehyde, with silicon halides provide a novel non-hydrolytic sol-gel route to silica.
101 citations
TL;DR: The Fe 2 O 3 -catalyzed oxidation of ketones with molecular oxygen (1 atm) in the presence of an aldehyde at room temperature gives the corresponding lactones or esters highly efficiently as discussed by the authors.
100 citations
100 citations
TL;DR: In this paper, it was shown that reaction of aryl, benzyl, alkyl and functionalised alkyls acrylic esters with benzaldehyde, in the presence of 1,4-diazabicyclo[2.2] octane, strongly depends upon the electronic and steric effects of the ester part.
97 citations
94 citations
TL;DR: In this paper, an efficient one-pot synthesis of anilinobenzylphosphonates using BF3OEt2 as a catalytic catalyst was achieved from aniline, benzaldehyde, and dialkylphosphite.
89 citations
TL;DR: The title reaction with unsubstituted silyl ketene acetals proceeds with high enantioselectivity, and in the latter case good diastereoselectivities favoring the antiβ-hydroxy-α-methyl esters in all reported cases.
84 citations
67 citations
TL;DR: In this paper, benzaldehyde diacetates were selectively converted to corresponding benzaldehydes using Ceric Ammonium Nitrate (CAN) coated on silica in dichloromethane.
TL;DR: In this article, aldehyde with chiral aldimine which is derived from benzaldehyde and (R)-phenylglycinol methyl ether showed a remarkable temperature effect on the sense of chiral induction.
TL;DR: In this paper, the second-order rate constants of benzyl alcohol oxidation and the potential values of the ruthenium(IV)/ ruthensium(II1) redox couples of the oxorUThenium complexes or the Hammett u values of substituents of the para-substituted triphenylphosphine ligands were observed.
Abstract: Oxoruthenium complexes which contain para-substituted triphenylphosphine ligands cleanly oxidize para-substituted benzyl alcohols to the corresponding benzaldehydes. Linear free energy correlations between the logarithms of the second-order rate constants of benzyl alcohol oxidation and either the potential values of the ruthenium(IV)/ ruthenium(II1) redox couples of the oxoruthenium complexes or the Hammett u values of the substituents of the para-substituted triphenylphosphine ligands were observed. However, there were no good correlations for plots of log (kx/kH) versus the Hammett substituent constants u, u+, or u- for the oxidation of the para-substituted benzyl alcohols by [R~(bpy)~(O)PPh~](Clo~)~. Notably, the plot of log (kx/k~) - u* versus 6, where u* is the free radical stabilization constant, gave an excellent correlation with p = -0.57 and R2 = 0.99 for the oxidation of the parasubstituted benzyl alcohols by [Ru(bpy)2(O)PPh,] (C10& in methylene chloride. From these and other results, we propose a reaction pathway for the oxidation of benzyl alcohol by oxoruthenium(1V) complexes which involves a partial hydrogen atom abstraction from the benzylic carbon in the rate-determining step.
TL;DR: In this article, NbCl3 was shown to be a promising reagent for further synthetic applications, due to its stereoselectivity and easy control of DME mediated reactions.
TL;DR: The denitrifying Pseudomonas strain K172 was grown with a generation time of 6 h to a cell density of 0.4 g (dry weight) per liter with toluene and nitrate as substrates and it was found that anaerobic cell suspensions oxidize [ 14C]toluene first to [14C]benzyl alcohol and subsequently to [13C] Benzaldehyde.
Abstract: The denitrifying Pseudomonas strain K172 was grown with a generation time of 6 h to a cell density of 0.4 g (dry weight) per liter with toluene and nitrate as substrates. We found that anaerobic cell suspensions oxidize [14C]toluene first to [14C]benzyl alcohol and subsequently to [14C]benzaldehyde. This proves that the methyl group of toluene is oxidized without molecular oxygen to a hydroxymethyl group.
TL;DR: In this paper, three routes were explored for their potential to produce the aromatic aldehydes benzaldehyde, p -hydroxybenzaldehyde, and vanillin, which are important flavor components.
TL;DR: In this paper, the authors investigated the degradation of cis-3,5-dimethylcyclohexanone (6) with chiral lithium amide bases and found that the resulting lithium enolates react with benzaldehyde, acetic anhydride, or trimethylsilyl chloride.
Abstract: Deprotonation of cis-3,5-dimethylcyclohexanone (6) with chiral lithium amide bases has been investigated. The resulting lithium enolates react with benzaldehyde, acetic anhydride, or trimethylsilyl chloride. Effects of solvents and additives on the selectivity of these reactions have been studied
TL;DR: In this paper, α-aminonitriles and bis(α-)aminonitrile are prepared by adding a primary amine to a mixture of aldehyde/trimethylsilyl cyanide (TMSCN).
TL;DR: In the presence of Yamamoto's chiral (acyloxy)borane catalyst (III) and trifluoroacetic anhydride (TAN), homoallylic alcohols with high diastereo and enantioselectivity can be obtained as mentioned in this paper.
Abstract: Addition of achiral allylstannanes to achiral aldehydes in the presence of Yamamoto's chiral (acyloxy)borane catalyst (III) and trifluoroacetic anhydride affords homoallylic alcohols with high diastereo- and enantioselectivity. For example, crotonoaldehyde (1c) and (E)-tributyl(2-methyl-2-pentenyl)stannane (2) gave (3S,4S,5E)-3-ethyl-2-methyl-1,5-heptadien-4-ol (3c) in 85% yield and 95% enantiomeric excess.
TL;DR: In this paper, ortho-substituted [Cr(CO)3(benzaldehyde)] complexes are obtained via nucleophilic addition of alkyl-and aryllithium reagents to a [Cr[CO]3(phenylmethaneimine)] complex followed by endo-hydride abstraction with triphenylmethyl cation.
Abstract: ortho-Substituted [Cr(CO)3(benzaldehyde)] complexes are obtained via nucleophilic addition of alkyl- and aryllithium reagents to a [Cr(CO)3(phenylmethaneimine)] complex followed by endo-hydride abstraction with triphenylmethyl cation. This sequence, when carried out with a [Cr(CO)3(benzaldehyde SAMP hydrazone)] complex affords substituted derivatives (Me, Bu, Ph, vinyl) with high (=/>97%) diastereoselectivity and, after hydrolysis, ortho- substituted [Cr(CO)3(benzaldehyde)] ((S)-1) complexes of high enantiomeric purity.
TL;DR: Mutant strains of S. cerevisiae lacking some or all of the ADH isoenzymes, ADH I, II, and III, manifested similar rates for bioconversion of benzaldehyde to benzyl alcohol in both aqueous and two‐phase systems.
Abstract: Whole cells of Saccharomyces cerevisiae analyzed the conversion of benzaldehyde to benzyl alcohol in aqueous-organic biphasic media. Reaction rate increased dramatically as moisture content of the solvent was increased in the range 0% to 2%. The highest biotransformation rates were observed when hexane was used as organic solvent. Benzaldehyde was also converted to benzyl alcohol by a cell-free crude extract in biphasic systems containing hexane, although the rate of product formation was much lower. Mutant strains of S. cerevisiae lacking some or all of the ADH isoenzymes, ADH I, II, and III, manifested similar rates for bioconversion of benzaldehyde to benzyl alcohol in both aqueous and two-phase systems. In general, conversion rates observed in aqueous media were 2 to 3 times higher than those observed in hexane containing 2% moisture.
TL;DR: In this paper, a chiral induction of 82% ee was observed in the addition reaction of diethylzinc to benzaldehyde using N-hydroxyethylpyrrolidines as chiral catalyst ligands.
TL;DR: In this paper, the three consecutive steps of anodic toluene oxidation in methanol, namely the two-electron oxidation of benzyl alcohol to benzyl methyl methylether, the twoelectron oxidisation of benzaldehyde to benzaldehyde dimethylacetal and the multielectron oxidization of benzldehydes to a mixture of unknown products was performed, using voltammetry at rotating and stationary disc electrodes and the rotating ring-disc electrodes in methenol, ethanol and acetonitrile as solvents.
TL;DR: In this paper, a unimolecular cleavage reaction was proposed to produce substituted benzaldehyde and tert-butyl nitroso anion radical in acetonitrile (ACN).
TL;DR: In this article, it was shown that carbonyl metathesis of aldehydes can be accomplished as a gas-solid reaction on a reduced TiO2(001) single crystal under ultrahigh vacuum (UHV) conditions.
Abstract: Previous work in our laboratory indicated that carbonyl metathesis of aldehydes can be accomplished as a gas-solid reaction on a reduced TiO2(001) single crystal under ultrahigh vacuum (UHV). This reaction requires the presence of cations in lower oxidation states on the surface, but does not require Ti0 as suggested by previous studies in the liquid phase. In the course of attempts to carry out this reaction catalytically, TPD experiments on TiO2 single crystals and powders were conducted. In addition to the aldolization of acetaldehyde to crotonaldehyde, carbonyl metathesis of acetaldehyde to butene was observed. Benzaldehyde TPD on reduced TiO2 powder gave substantial amounts of styrene (PhCH=CH2) which is most likely formed by disproportionation of stilbene (PhCH=CHPh), the metathesis product observed in single crystal studies. Addition of Ti metal to titania resulted in the formation of large amounts of toluene (by unimolecular reduction) rather than stilbene or styrene (by bimolecular reductive coupling). More importantly, it was possible to form 1-phenylpropene (PhCH=CH-CH3), a cross-coupling product, by the co-metathesis of benzaldehyde and acetaldehyde on reduced titania, ceria and iron oxide powders during TPD at atmospheric pressure. These studies represent an extension of stoichiometric reactions observed on single crystals in UHV toward novel catalysis. While carbonyl metathesis has still not been accomplished catalytically, its observation during TPD of aldehydes on dihydrogen-reduced oxides has demonstrated the feasibility of each of the steps required to close a catalytic cycle.
TL;DR: Boron trifluoride monohydrate catalyzed thiolation of aldehydes and ketones with thiols and triethylsilane to the corresponding sulfides was carried out in good to excellent yields as discussed by the authors.
Abstract: Boron trifluoride monohydrate catalyzed thiolation of aldehydes and ketones with thiols and triethylsilane to the corresponding sulfides was carried out in good to excellent yields
TL;DR: The influence of the electronic nature and the position of substitutions on the aromatic ring of the substrate on the velocity of the catalysed reactions provided some indications concerning the transition state during the oxidation of the substrates, and on the rate-limiting steps of the enzymes.
Abstract: The substrate-specificities of benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase, encoded by TOL plasmid pWW0 of Pseudomonas putida mt-2, were determined. The rates of benzyl alcohol dehydrogenase-catalysed oxidation of substituted benzyl alcohols and reduction of substituted benzaldehydes were independent of the electronic nature of the substituents at positions 3 and 4. Substitutions at position 2 of benzyl alcohol affected the reactivity of benzyl alcohol dehydrogenase: the velocity of the benzyl alcohol dehydrogenase-catalysed oxidation was lower for compounds possessing electron-withdrawing substitutions. In the reverse reaction of benzyl alcohol dehydrogenase, none of the substitutions tested influenced the apparent kcat. values. The rates of benzaldehyde dehydrogenase-catalysed oxidation of substituted benzaldehydes were influenced by the electronic nature of the substitutions: electron-withdrawing groups at positions 3 and 4 favoured the oxidation of benzaldehydes. Substitution at position 2 of benzaldehyde greatly diminished the benzaldehyde dehydrogenase-catalysed oxidation. Substitution at position 2 with electron-donating groups essentially abolished reactivity, and only substitutions that were strongly electron-withdrawing, such as nitro and fluoro groups, permitted enzyme-catalysed oxidation. The influence of the electronic nature and the position of substitutions on the aromatic ring of the substrate on the velocity of the catalysed reactions provided some indications concerning the transition state during the oxidation of the substrates, and on the rate-limiting steps of the enzymes. Pseudomonas putida mt-2 containing TOL plasmid pWW0 cannot grow on toluene derivatives substituted at position 2, nor can it grow on 2-substituted benzyl alcohols or aldehydes. One of the reasons for this may be the substrate-specificities of the benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase.
TL;DR: An asymmetric aldol reaction of (+)-chromium(0)-complexed benzaldehyde 4 with the titanium enolate generated from the ethanethioate 5 provided the anti-aldol product 6 in a highly stereoselective manner, which was subsequently converted to the taxol C-13 side chain this paper.
Abstract: An asymmetric aldol reaction of (+)-chromium(0)-complexed benzaldehyde 4 with the titanium enolate generated from the ethanethioate 5 provided the anti -aldol product 6 in a highly stereoselective manner, which was subsequently converted to the taxol C-13 side chain.