Showing papers on "Benzaldehyde published in 1993"
TL;DR: In this article, the reaction of unsaturated hydroxy esters (X=OMe, R 2 =H, Me) and amides with benzaldehyde and potassium alkoxide or amide bases is reported.
Abstract: Reaction of the illustrated unsaturated hydroxy esters (X=OMe, R 2 =H, Me) and amides (X=N(Me)OMe, R 2 =H, Me) with benzaldehyde and potassium alkoxide or amide bases is reported. The resulting benzylidene acetals are obtained in good yields (71-84%) and with hidh selectivity (>90:10). In addition to an exploration of the scope of the reaction, a mechanistic study, involving the use of deuterated benzaldehyde to ascertain the rate-determining step of the process, is described
147 citations
TL;DR: In this paper, a mixture of 2-methylpropanal and mixed heteropolyoxometalate NPV 6 Mo 6 (3) was used to give the corresponding epoxides in moderate to good yields.
Abstract: Heteropolyoxometalate-catalyzed oxidations of organic compounds such as olefins and cyclic ketones with molecular oxygen in the presence of an aldehyde were examined. Olefins were epoxidized with dioxygen in the presence of 2 equiv of 2-methylpropanal under the influence of a catalytic amount of the mixed heteropolyoxometalate NPV 6 Mo 6 (3) to give the corresponding epoxides in moderate to good yields. This catalytic oxidation method was also applied to the epoxidation of allylic and homoallylic alcohols. In the absence of olefins, the aldehydes were efficiently converted into the corresponding carboxylic acids. In addition, the Baeyer-Villiger oxidation of cyclic ketones was accomplished by using benzaldehyde instead of 2-methylpropanal as the aldehyde
116 citations
TL;DR: In this article, a simplified and highly efficient protocol for asymmetric allylation of aldehydes using allyltri-n-butylstannane and a chiral Lewis acid is described.
115 citations
TL;DR: In this paper, allyltrichlorosilanes regioselectively react with aldehydes in N,N-dimethylformamide (DMF) without catalyst to afford the corresponding homoallylic alcohols in high yields.
112 citations
TL;DR: In this article, a simple, extremely fast, and high yielding method for the selective deprotection of benzaldehyde diacetates is described which occurs under mild conditions on neutral alumina surface.
111 citations
TL;DR: In this paper, the electronic properties of para-substituents were investigated for α-hydroxyphosphonates in the presence of La-BINOL complex.
Abstract: Hydrophosphonylation of aromatic aldehydes with diethyl phosphite in the presence of catalytic amount of La-BINOL complex ( 2 ) proceeded enantioselectively to give the corresponding α-hydroxyphosphonates in good yield. Enantioselectivity was found to depend on the electronic nature of para -substituents.
107 citations
TL;DR: GSH may play an important role in protection against the induction of ROS generation in the CNS and liver following exposure to toluene, in addition to existing studies on cytochrome P450 oxidation and aldehyde dehydrogenase oxidation.
90 citations
83 citations
TL;DR: In this paper, the catalytic activity of various metal salts has been studied, including metal catalysts for the Baeyer-Villiger oxidation of ketones using molecular oxygen and benzaldehyde.
82 citations
TL;DR: The results provide a description of final product distributions for the alternative reactions catalyzed by the multifunctional enzyme and an estimate of rate constants for a complete mechanism.
Abstract: Liver alcohol dehydrogenase catalyzes the reaction of NAD+ and benzyl alcohol to form NADH and benzaldehyde by a predominantly ordered reaction. However, enzyme-alcohol binary and abortive ternary complexes form at high concentrations of benzyl alcohol, and benzaldehyde is slowly oxidized to benzoic acid. Steady-state and transient kinetic studies, equilibrium spectrophotometric measurements, product analysis, and kinetic simulations provide estimates of rate constants for a complete mechanism with the following reactions: (1) E E-NAD+ E-NAD(+)-RCH2OH E-NADH-RCHO E-NADH E ; (2) E-NADH E-NADH-RCH2OH E-RCH2OH E; (3) E-NAD+ E-NAD(+)-RCHO-->E- NADH-RCOOH E-NADH. The internal equilibrium constant for hydrogen transfer determined at 30 degrees C and pH 7 is about 5:1 in favor of E-NAD(+)-RCH2OH and has a complex pH dependence. Benzyl alcohol binds weakly to free enzyme (Kd = 7 mM) and significantly decreases the rates of binding of NAD+ and NADH. The reaction of NAD+ and benzyl alcohol is therefore kinetically ordered, not random. High concentrations of benzyl alcohol (> 1 mM) inhibit turnover by formation of the abortive E-NADH-RCH2-OH complex, which dissociates at 0.3 s-1 as compared to 6.3 s-1 for E-NADH. The oxidation of benzaldehyde by E-NAD+ (Km = 15 mM, V/E = 0.4 s-1) is inefficient relative to the oxidation of benzyl alcohol (Km = 28 microM, V/E = 3.1 s-1) and leads to a dismutation (2RCHO-->RCH2OH + RCOOH) as E-NADH reduces benzaldehyde. The results provide a description of final product distributions for the alternative reactions catalyzed by the multifunctional enzyme.
76 citations
TL;DR: The Baylis-Hillman reaction of acrylic derivatives with benzaldehydes is more efficient when the arene is complexed to the electrophilic Cr(CO)3 group as discussed by the authors.
TL;DR: A series of three chromium tricarbonyl benzaldehyde acetal complexes were prepared from benzaldehyde diethyl acetal and (+)-diethyl tartrate, and the diastereoselectivity of lithiation was determined by quenching of the resulting anions with Me 3 SiCl as discussed by the authors.
Abstract: A series of three chromium tricarbonyl benzaldehyde acetal complexes were prepared from benzaldehyde diethyl acetal and (+)-diethyl tartrate. These compounds were ortho-lithiated by a number of bases, and the diastereoselectivity of lithiation was determined by quenching of the resulting anions with Me 3 SiCl. Complexes 1 and 2 were found to give moderate levels of diastereoselection, while the combination of complex 3 and 2.4 equiv of n-BuLi ruder equilibrating conditions gave an 86% de of silylated products. Other electrophiles gave slightly higher de's (88% to ≥94%), and all products derived from 3 were separable by column chromatography. Hydrolysis of the ortho-methylated product to the corresponding benzaldehyde complex (-)-21 as well as X-ray structural analysis of the trimethylsilylated complex demonstrated that preferential pro-R deprotonation had occured
TL;DR: In this paper, a chiral quarternary ammonium fluoride was used for catalytic enantioselective aldol reactions of silyl enol ethers with benzaldehyde in high enantiomeric excesses.
TL;DR: Alkylidene cyclopropane derivatives are obtained by reaction of biscyclopropyl titanocene with several types of carbonyl compounds, including aldehydes, ketones and esters.
TL;DR: In this paper, the products of the gas phase reactions of styrene and 2-vinylpyridine with O 3, OH radicals, and NO 3 radicals have been studied at room temperature and atmospheric pressure of air.
Abstract: The products of the gas-phase reactions of styrene and 2-vinylpyridine with O 3 , OH radicals, and NO 3 radicals have been studied at room temperature and atmospheric pressure of air. The reaction kinetics were also measured for those reactions not previously examined. The major products of the ozone reaction with styrene were formaldehyde and benzaldehyde, each with yields of ∼40%. The OH radical reaction with styrene also formed benzaldehyde and formaldehyde with yields of 63±6% and 72±7%, respectively. The reaction of styrene with the NO 3 radical formed equal, minor yields (ca. 11%) of HCHO and C 6 H 6 CHO, with the remaining unidentified products consisting of transient and stable species which contain ONO 2 , OONO 2 , and C=O groups
TL;DR: A series of dicationic PdII-acetonitrile complexes containing bi-and tridentate nitrogen and bidentate phosphine ligands (some of which are chiral) has been prepared as their BF4 salts as mentioned in this paper.
Abstract: A series of dicationic PdII-acetonitrile complexes containing bi- and tridentate nitrogen and bidentate phosphine ligands (some of which are chiral) has been prepared as their BF4 salts. The molecular structures for two of these, [Pd(CH3CN)2(bipy)] (BF4)2 (4) and [Pd(CH3CN)((pybox)(i-Pr))] (BF4)2((S,S)-pybox(i-Pr) = 2,6-bis[(S)-4′-isopropyloxazolin-2′-yl]pyridine, 5) have been determined by X-ray diffraction. All of these complexes are shown to be effective homogeneous catalysts for the aldol-type condensation of the isonitrile, methyl isocyanoacetate, with benzaldehyde. Two isonitrile complexes, [Pd(2,2′-bipyridyl)(CNCH2COOCH3)2] (BF4)2 and [Pd((S,S)-pybox(i-Pr))(CNCH2COOCH3)] (BF4)2, have also been prepared.
TL;DR: The O,O-ketene acetal of E-configuration reacted rapidly to afford the syn aldol products with high diastereoselectivity (93/7-99/1)
Abstract: O-(Silacyclobutyl) ketene acetals derived from esters, thiol esters, and amides reacted with a variety of aldehydes at room temperature without the need for catalysts. The O,O-ketene acetal of E-configuration reacted rapidly to afford the syn aldol products with high diastereoselectivity (93/7-99/1)
TL;DR: Allylation of carbonyl compounds (aldehydes, ketones, esters, lactones, acid anhydrides) proceeds smoothly at room temperature by the reaction of an allylic benzoate or allylic phenyl ether, diethylzinc, and a catalytic amount of Pd(0)-complex in THF under N2 as discussed by the authors.
TL;DR: The Cp2TiPh2-catalyzed reaction of cyclopentanone or cyclohexanones with benzaldehydes brought about the cross-aldol condensation to give the corresponding 2,5-bis(substitutedbenzylidene)cyclopentanones or 2,6-bis (substitized benzylidsene)cyclohexansones in good yields under milder conditions than those previouly reported as mentioned in this paper.
Abstract: The Cp2TiPh2-catalyzed reaction of cyclopentanone or cyclohexanones with benzaldehydes brought about the cross-aldol condensation to give the corresponding 2,5-bis(substitutedbenzylidene)cyclopentanones or 2,6-bis(substitutedbenzylidene)cyclohexanones in good yields under milder conditions than those previouly reported.
TL;DR: In this paper, the authors showed that benzaldehyde, its ortho-and meta-substituted derivatives and acetophenone underwent dimerization reactions on treatment with samarium(II) iodide in the presence of HMPA.
TL;DR: In this article, the Wittig reaction of nonstabilized ylides with benzaldehyde and benzophenone was investigated by means of carbonyl 14 C kinetic isotope effects, substituent effects, and isotope-scrambling and probe experiments.
Abstract: The Wittig reaction of nonstabilized ylides with benzaldehyde and benzophenone was investigated in detail by means of carbonyl- 14 C kinetic isotope effects, substituent effects, and isotope-scrambling and probe experiments. The reaction with benzophenone gave the carbon isotope effects and the Hammett p values of considerable magnitude both in Li salt-free and salt-present conditions. In contrast, they are quite small for the reaction with benzaldehyde. Enone-isomerization and dehalogenation probe experiments indicated that the nonstabilized ylide has enough ability to transfer an electron to benzaldehyde and benzophenone
TL;DR: In this article, the use of β-hydroxysulfoxides 1−8 as chiral catalysts in the enantioselective addition of diethylzinc to benzaldehyde is reported.
Abstract: The first examples of the use of readily available β-hydroxysulfoxides 1–8 as chiral catalysts in the enantioselective addition of diethylzinc to benzaldehyde are reported. The increase of the steric hindrance around the chiral ligand OH group improves the e.e. of the obtained 1-phenylpropanol, which is higher with tertiary alcohols (25–45%) than with secondary ones (
TL;DR: In this article, the chemistry of the reduction process of V 2 O 5 with mixtures of aliphatic and benzyl alcohols was studied using several analytical techniques, including IR spectroscopy.
Abstract: The chemistry of the reduction process of V 2 O 5 with mixtures of aliphatic and benzyl alcohols was studied using several analytical techniques. The aromatic alcohol, which acted as the reducing agent, was invariably oxidized to benzaldehyde while further oxidation to benzoic acid often occurred. The presence of soluble vanadium (V) alkoxides was detected through IR spectroscopy. At the higher reduction temperatures, which varied between 353 and 393 K, V 2 O 4 , appeared in the solid residue. In no case, however, was the vanadium pentoxide completely reduced with the alcohol mixture. The nature and proportion of the aliphatic alcohol defines the reflux temperature and therefore the rate of the kinetically controlled redox process. The reduction of V 2 O 5 is completed upon addition of H 3 PO 4 (100%). The precursors obtained invariably showed the X-ray diffraction pattern of VOHPO 4 ·/2H 2 O. The extent of disorder of the lattice in the direction perpendicular to the (010) plane increased with a higher proportion of benzyl alcohol in the reduction mixture. The oxidation of n-butane to maleic anhydride was studied using a plug flow reactor. The equilibrated catalysts display very similar X-ray diffraction patterns characteristic of (VO) 2 P 2 O 7 . No correlation was found between the extent of disorder of the precursors prepared in organic medium and the catalytic performance of the equilibrated solids.
TL;DR: The biosynthesis of the antibiotic reductiomycin (I) in Streptomyces xanthochromogenus was investigated by feeding experiments with radioactive and stable isotope-labeled precursors and was interpreted in terms of a dioxygenase mechanism for the ring cleavage reaction and pyridoxal phosphate catalysis for the ALA cyclization.
Abstract: The biosynthesis of the antibiotic reductiomycin (I) in Streptomyces xanthochromogenus was investigated by feeding experiments with radioactive and stable isotope-labeled precursors. NMR and mass spectroscopic analyses of the labeled I samples revealed that the acetoxy group comes from acetate, the 2-amino-3-hydroxycyclopent-2-enone moiety arises by a novel intramolecular cyclization of 5-aminolevulinic acid (ALA), and the dihydrofuranylacrylic moiety is formed by aromatic ring cleavage of a symmetrical product of the shikimate pathway. Both 4-hydroxy-[7-[sup 13]C]benzoic acid and 4-hydroxy-[7-[sup 13]C]benzaldehyde label 1 very efficiently, and deuterium from various positions in these precursors is incorporated into the predicted positions in the dihydrofuranylacrylic acid moiety of 1. The results are interpreted in terms of a dioxygenase mechanism for the ring cleavage reaction and pyridoxal phosphate catalysis for the ALA cyclization. 42 refs., 6 figs., 5 tabs.
TL;DR: In this paper, silylphosphite compounds, (rac-O,O-binaphtholato)POSiR3 (R3 = Ph3, tBuMe2, Et3) have been synthesised by the reactions of PC1 and R3SiOH.
TL;DR: An antitumor styryl-lactone, (+)-goniofufurone was synthesized in a highly diastereoselecdve manner from (+)-tricarbonyl(η6-2-trimethylsilylbenzaldehyde)chromium(0) complex through stereoselective aldol reactions as crucial steps as discussed by the authors.
TL;DR: In this paper, the selective hydrogenation of benzoic acid to benzaldehyde on ZrO2 and Cr2O3-ZrO 2 at 523 K was studied by IR spectroscopy.
Abstract: The selective hydrogenation of benzoic acid to benzaldehyde on ZrO2 and Cr2O3–ZrO2 at 523 K was studied by IR spectroscopy. An enhancement of the hydrogenation rate of benzoic acid by Cr2O3 doping to ZrO2 was observed. The main role of Cr2O3 was considered to be the step of activating hydrogen. An intermediate species was observed based on the IR bands during a transformation from the adsorbed benzaldehyde to the benzoate at lower temperatures. This is discussed in conjunction with the reaction mechanism of the hydrogenation. The intermediate species was regarded as being the chemisorbed benzaldehyde by an analysis of the observed IR bands.
TL;DR: In this paper, the first powers of the concentrations of substrate, oxidant, and acid have been observed to have a small inverse kinetic isotope effect (k H /k D = 0-80), suggesting the formation of a cationic intermediate in the rate determining step of the reaction.
Abstract: The kinetics of oxidation of styrene and substituted styrenes by quinolinium dichromate (QDC) in dimethyl formamide, in the presence of acid, has been investigated. The rate of the reaction is dependent on the first powers of the concentrations of substrate, oxidant, and acid. A small inverse kinetic isotope effect has been observed (k H /k D =0-80). Correlation with σ yielded a ρ value of -4-0, suggesting the formation of a cationic intermediate in the rate-determining step of the reaction. Subsequent cleavage of the carbon-carbon bond yielded benzaldehyde and formaldehyde