An aluminium(III) chloride‐catalyzed three‐component reaction of aromatic aldehydes, nitroalkanes, and sodium azide has been developed; this reaction sequence can be applied to a broad substrate scope and affords the corresponding 4‐aryl‐NH‐1,2,3‐triazoles in good to excellent yields. The milder reaction conditions and easier operation make this AlCl3‐catalyzed protocol more advantageous for the synthesis of 4‐aryl‐NH‐1,2,3‐triazoles.
Benzaldehyde lyase from the Pseudomonas fluorescens catalyzes the reaction of aromatic aldehydes with nitroso compounds and furnishes N‐arylhydroxamic acids in high yields. Aromatic aldehydes and benzoins are converted into enamine‐carbanion‐like intermediates prior to their reaction with nitroso compounds. The kinetic resolution of rac‐2‐hydroxy‐1,2‐diphenylethanones furnished (S)‐benzoins and arylhydroxamic acids with high enantioselectivities and conversions. 相似文献
A series of novel L ‐proline derived thioamides has been synthesised. They have been evaluated as organocatalysts in the direct asymmetric aldol reaction for the first time. Thioamides exhibit catalytic ability higher than proline itself and the model aldol reaction of 4‐cyanobenzaldehyde with acetone proceeds well in the presence of 5 mol % of catalyst (ee up to 100%). Other aromatic aldehydes gave aldol products with high ees and moderate yields. Small changes in the catalyst's structure [e.g., N‐Bn versus N‐CH(CH3)Ph] as well as the addition of an acid have a profound effect on their activity. The unexpected formation of the catalyst‐derived cyclic adducts was observed and their reactivity was established giving valuable insight into the course of the reaction. 相似文献
An efficient, simple and clean solvent-free procedure for the preparation of N-sulfonyl imines is described. The reaction of sulfonamides with different aromatic aldehydes in the presence of silica-phosphinoxide (Silphox) [POCl3?n(SiO2)n] as a new and heterogeneous reagent affords the title compounds in good to high yields. 相似文献
Aqueous suspensions of iridium nanoparticles produced by the chemical reduction of IrCl3 assisted by sonication, in the presence of N,N‐dimethyl‐N‐cetyl‐N‐(2‐hydroxyethyl)ammonium chloride salt as surfactant, have shown an efficient activity for the catalytic hydrogenation of various aromatic derivatives in biphasic media under mild conditions. These nanocatalysts can be reused for further runs with a total conservation of activity and provided significant catalytic lifetime for anisole hydrogenation in pure water with 3000 total turn‐over (TTO). 相似文献
The highly enantioselective organo‐co‐catalytic aza‐Morita–Baylis–Hillman (MBH)‐type reaction between N‐carbamate‐protected imines and α,β‐unsaturated aldehydes has been developed. The organic co‐catalytic system of proline and 1,4‐diazabicyclo[2.2.2]octane (DABCO) enables the asymmetric synthesis of the corresponding N‐Boc‐ and N‐Cbz‐protected β‐amino‐α‐alkylidene‐aldehydes in good to high yields and up to 99% ee. In the case of aza‐MBH‐type addition of enals to phenylprop‐2‐ene‐1‐imines, the co‐catalytic reaction exhibits excellent 1,2‐selectivity. The organo‐co‐catalytic aza‐MBH‐type reaction can also be performed by the direct highly enantioselective addition of α,β‐unsaturated aldehydes to bench‐stable N‐carbamate‐protected α‐amidosulfones to give the corresponding β‐amino‐α‐alkylidene‐aldehydes with up to 99% ee. The organo‐co‐catalytic aza‐MBH‐type reaction is also an expeditious entry to nearly enantiomerically pure β‐amino‐α‐alkylidene‐amino acids and β‐amino‐α‐alkylidene‐lactams (99% ee). The mechanism and stereochemistry of the chiral amine and DABCO co‐catalyzed aza‐MBH‐type reaction are also discussed. 相似文献
A simple, rapid and highly regioselective green protocol has been developed for the halogenation of aromatic systems with N‐halosuccinimides using room temperature ionic liquids (ILs) as novel and recyclable reaction media to produce the corresponding halogenated aromatic compounds in high to quantitative yields. N‐Halosuccinimides show enhanced reactivity in ionic liquids thereby reducing the reaction times dramatically and improving the yields substantially. 相似文献
A direct three‐component reaction of aldehydes, amines and diaryl phosphites was catalyzed by a zinc(II) complex of 1,3‐bis(imidazolin‐2‐ly)pyridine (pybim) giving the corresponding α‐aminophosphonates in good yield with good enantioselectivity. The reaction was applied to a wide variety of aromatic aldehydes to give products with excellent yields (up to 99%) and enantiomeric excesses (up to 93% ee). 相似文献
The FT-i.r. and 1H n.m.r. spectroscopic analyses of oils or maltenes from a Spanish lignite (Utrillas, Teruel), are reported. These oils were obtained by depolymerization with alkyl aromatic ethers (anisole, 3-methylanisoleand 1,3-dimethoxybenzene) catalyzed by Lewis acids ZnCl2, AlCl3, SbCl3and BF3 (as boron trifluoride etherate), at atmospheric pressure and temperatures <220 °C. Bands due to aromatic ethers in the i.r. and n.m.r. spectra of the oils obtained by depolymerization indicate solvent incorporation. Oils obtained by direct lignite extraction showed 25% aromatic H and some Hα (≈3%) without OH groups. These appeared in some oils obtained by depolymerization with AlCl3 and were due to secondary reactions with the aromatic extract. Oils derived from processes with good yields showed increases in aromaticity. The extent of substitution of aromatic rings in oils obtained by depolymerization was less than for oils directly extracted. All the oils studied show a low degree of condensation. 相似文献
An efficient enantioselective aza‐Henry reaction of nitroalkanes to imines bearing a benzothiazole moiety catalyzed by a Cinchona‐based squaramide has been developed. In the reaction of imines, the corresponding products were obtained in good to excellent yields (up to 99%) with excellent enantioselectivities (up to >99% ee) for most of the aromatic substituted imines. The imines with electron‐withdrawing groups gave better yields than those bearing electron‐donating groups in the aza‐Henry reaction. Moreover, a one‐pot three‐component enantioselective aza‐Henry reaction using 2‐aminobenzothiazoles, aldehydes, and nitromethane was also developed. Moderate to good yields and high enantioselectivities were obtained in the one‐pot cases (up to 98% ee). 相似文献
A novel environmentally benign procedure for the synthesis of 2‐aryl‐ or 2‐hetaryl‐4(3H)‐quinazolinones by condensation of anthranilamide with various aromatic aldehydes in polyethylene glycol under microwave irradiation has been developed. In contrast with other reported methods, this procedure provides the corresponding quinazolinones with good to high yields and purity, in very short reaction times and without the use of an oxidant. 相似文献
A novel chiral H8‐1,1′‐binaphthyl‐based amino alcohol ligand (1Ra,2S,3R)‐ 2 has been synthesized and applied in the direct nucleophilic addition of organozincs (alkynylzinc and arylzinc prepared in situ) to aldehydes, yielding the corresponding optically active propargylic alcohols and diarylmethanols in high yields and good to excellent enantioselectivities. For the asymmetric arylation reaction, one catalyst (1Ra,2S,3R)‐ 2 can afford both enantiomers of many pharmaceutically interesting diarylmethanols by a proper combination of various arylzinc reagents and aldehydes. 相似文献
An efficient palladium‐catalyzed C H acylation with aldehydes using tert‐butyl hydroperoxide (TBHP) transforms various anilides into synthetically useful 2‐aminobenzophenone derivatives under mild conditions (40 °C, 3 h). The acylation reaction exhibits excellent regioselectivity and functional group tolerance, and simple aromatic aldehydes, functionalized aliphatic aldehydes and heteroaromatic aldehydes are effective coupling partners. The acylation reaction is probably initiated by a rate‐limiting electrophilic C H cyclopalladation (kH/kD=3.6; ρ+=−0.74) to form an arylpalladium complex, followed by acyl radical functionalization. 相似文献
The benzylation of benzene and substituted benzenes reaction employing benzyl chloride as the alkylating agent over a series
of Indium-containing mesoporous silicas with different In contents has been investigated. These materials (In-HMS-n) have been characterized by chemical analysis, N2 adsorption/desorption isotherm, X-ray diffraction (XRD) and FTIR spectroscopy. The mesoporous Indium-containing materials
showed both high activity and high selectivity for benzylation of benzene. The activity of these catalysts for the benzylation
of different aromatic compounds is in the following order: benzene > toluene > p-xylene > anisole. More interesting is the observation that these catalysts are always active and selective for large molecules
like naphthenic compounds such as methoxynaphthalene. Kinetics of the benzene benzylation over these catalysts have also been
investigated. 相似文献
With benzaldehyde as a model compound, the hydrogenation of aromatic aldehydes to aromatic hydrocarbons was investigated. Cu-HZSM-5 exhibited excellent catalytic performance for the reaction. The obtained catalysts were characterized by N2 adsorption/desorption, N2O chemisorptions, X-ray diffraction, NH3-temperature programmed desorption and X-ray photoelectron spectroscopy. It was found that Cu0 active species exhibited poor activity for the hydrogenation of benzene ring, while the strong acidity of HZSM-5 accelerated the hydrogenation reaction via hydrogen spillover phenomenon and the C–O activation effect. In addition, the catalyst was proved to be effective for the hydrogenation of a series of aromatic aldehydes to corresponding aromatic hydrocarbons. 相似文献
Graphitic carbon nitride (g‐C3N4) and N‐hydroxy compounds can function as a non‐metal photocatalytic system to activate O2 for the selective allylic oxidation under mild conditions, avoiding the employment of any metal derivative or organic oxidizing agents. Interestingly, the novel photocatalytic system affords a remarkably high selectivity towards the formation of aldehydes, especially in the oxidation of toluene. By combining the unique nature of g‐C3N4 (surface basicity, semiconductor features, high stability) and the remarkable catalytic oxidation reactivity of nitroxyl radicals, this photocatalytic system opens up a mild and efficent access for C H bond activation. 相似文献