Ti-exchanged ZSM-5 as heterogeneous catalyst for allylation of aldehydes with allyltributylstannane

Titanium exchanged ZSM-5 catalyst has been prepared by treating an aqueous solution of titanium (IV) chloride with ZSM-5. The supported catalyst has been explored as effective and reusable catalyst for allylation reaction of aldehydes with allyltributylstannane. The new catalytic system promotes efficiently the allylation reaction in toluene condition to produce homoallylic alcohols in high yield.     

Indium-mediated Barbier-type allylation of aldehydes as a convenient method for the highly enantioselective synthesis of homoallylic alcohols

We report a general method for the indium-mediated Barbier-type enantioselective allylation of both aromatic and aliphatic aldehydes using commercially available (1S,2R)-(+)-2-amino-1,2-diphenylethanol as a chiral auxiliary. Using only two equivalents of allyl bromide, excellent yields and very good to excellent enantioselectivities are obtained. To our knowledge, the enantioselectivities reported herein are the highest obtained for indium-promoted allylations of carbonyl compounds.     

Green synthesis of methyl trifluoropyruvate catalyzed by solid acids

Solid acids – NiSO₄/Al₂O₃, Fe₂(SO₄)₃/Al₂O₃ and TiO₂/SO₄²⁻ – appeared to be effective catalysts for the acid catalyzed synthesis of methyl ester of trifluoropyruvic acid. They are active at 150–180 °C.     

Asymmetric catalysis of ene reactions with trifluoropyruvate catalyzed by dicationic palladium(II) complexes

Chiral dicationic SEGPHOS-Pd(II) complex achieves a high chemical yield, (E)-olefin selectivity, anti-diastereoselectivity, along with high enantioselectivity even with less reactive mono- and 1,2-disubstituted olefins in this much less reactive ketone-ene reactions. The high levels of enantioselectivity stem from the effective shielding with diphenyl groups on phosphines caused by the narrow dihedral angle of metal complexes with SEGPHOS.     

Efficient allylation of aldehydes with allyltributylstannane catalyzed by CuI

Cuprous iodide has been found to be a very effective catalyst for allylation of aldehydes with allyltributylstannane. The catalytic system efficiently promotes the allylation reaction in DMF to produce homoallylic alcohols in high yield.     

Carbonyl allylation of aldehydes and ketones with allylic chlorides catalyzed by immobilization of palladium in MCM-41

The heterogeneous carbonyl allylation of aldehydes and ketones with allylic chlorides was achieved in DMF using SnCl₂ as reducing agent at 25-40 °C in the presence of a 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized palladium(II) complex [MCM-41-2N-Pd(II)], yielding a variety of homoallylic alcohols in good to high yields. This heterogeneous palladium catalyst exhibited higher activity than (N-propylethylenediamine)PdCl₂ and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 5 consecutive trials without any decreases in activity.     

Reactions of methyl trifluoropyruvate 2-pyridylimines with trimethyl phosphite

Reactions of methyl trifluoropyruvate 2-pyridylimines with trimethyl phosphite afford methyl 3-fluoroimidazo [1, 2-a]pyridine-2-carboxylates.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 460–462, February, 2005     

A selective and cost-effective method for the reductive deuteration of activated alkenes

A new single electron transfer reaction for the reductive deuteration of activated alkenes has been developed for the selective synthesis of α,β-dideuterio compounds. A cheap, stable and commercially-available sodium dispersion with high specific surface area is employed as the electron donor to replace the traditionally used sodium/liquid ammonium system. Deuterium source is provided by EtOD-d₁. Excellent yields and deuterium incorporations were obtained across a broad range of activated alkenes with good functional group tolerance. This method provided a cheap, efficient and operationally-simple method for the synthesis of deuterium labeled compounds.     

Adsorption of methyl mercaptan on surface modified activated carbon

The influence of surface modification of activated carbon on the adsorption of methyl mercaptan in N(2) was investigated. The modification of the activated carbon was carried out by treatment with HNO(3)/H(2)SO(4) solutions, heat-treatment in Ar, and adsorption of cetylamine. Acid-treatment increased the adsorption of methyl mercaptan compared with the original activated carbon, and the adsorbed amounts increased with ratio of H(2)SO(4) in HNO(3)/H(2)SO(4) solutions. This result suggests that hydrogen bonding between acidic groups formed by acid-treatment and thiol groups of methyl mercaptan plays a role in adsorption of methyl mercaptan on activated carbon.     

Free-radical reactions of methyl trifluoropyruvate with aldehydes

Methyl trifluoropyruvate reacts with aldehydes in the presence of catalytic amounts of benzoyl peroxide at 130–140°C to give β,β,β-trifluoro-α-(methoxycarbonyl)ethyl carboxylates. UV irradiation makes oligomerization of the initial ketoester predominant. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1763–1766, September, 1998.     

Indium triflate catalyzed allylation of ketones with diallyldibutyltin

A series of ketones underwent an allylation reaction using diallyldibutyltin in the presence of a catalytic amount of In(OTf)₃. The method was found to be superior to most of the known methods. Thus, a new allyltin reagent Bu₂Sn(allyl)₂/In(OTf)₃ for ketones was developed.     

Asymmetric synthesis of activated cyclopropanes catalyzed by cinchonidine as a chiral Brønsted base

Cinchonidine catalyzed the cyclopropanation reaction between chloromethyl ketones and β-substituted methylidenemalononitriles to give trans-cyclopropanes with enantioselectivity up to 82% ee. Experimental evidence suggests that cinchonidine functions as a chiral Brønsted base catalyst in the reaction and hydrogen bonding is essential for inducing high enantioselectivity.     

Acylimines of hexafluoroacetone and methyl trifluoropyruvate in cyclocondensation with 2-aminopyridines

Cyclocondensation of acylimines of hexafluoroacetone and methyl trifluoropyruvate with 2-aminopyridines afforded earlier unknown fluoro-containing 2H-pyrido[1,2-a][1,3,5]triazines. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1470–1473, June, 2005.     

Cascade rearrangement in the reaction of methyl trifluoropyruvate sulfonylimines with terminal alkynes

Methyl trifluoropyruvate benzene- and methanesulfonylimines react with hex-1-yne and phenylacetylene to give methyl N-sulfonyl-4-oxo-2-trifluoromethyl-4-R-but-2E-enimidates. The reaction mechanism includes the formation of a six-centered bipolar ion followed by its cascade rearrangement.     

Acylimines of hexafluoroacetone and methyl trifluoropyruvate in cyclocondensation with 2-aminothiazolines

Reactions of acylimines of hexafluoroacetone and methyl trifluoropyruvate with 2-aminothiazolines afforded fluorine-containing heterocycles of two structural types: 6,7-dihydro-2H-thiazolo[3,2-a][1,3,5]triazines and 2,3,5,6-tetrahydroimidazo[2,1-b]thiazoles. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1619–1622, July, 2005.     

Acylimines of methyl trifluoropyruvate in cyclocondensation with C,N-bisnucleophiles

Reactions of acylimines of methyl trifluoropyruvate with C,N-bisnucleophiles gave fluoro-containing heterocycles including the 5-oxo-4,5-dihydro-1H-pyrrole fragment. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2755–2760, December, 2005.     

Microwave assisted preparation of efficient activated carbon from grapevine rhytidome for the removal of methyl violet from aqueous solution

Grapevine rhytidome (the outer layer of bark on trunk), as an abundant and low-cost precursor, was used to prepare granular activated carbon with high surface area for the removal of methyl violet from aqueous solution. Microwave heating source was used to reduce the treatment time and energy consumption. To optimize the preparation, the effects of the different parameters, such as phosphoric acid concentration, acid/precursor weight ratio, impregnation time, microwave power, radiation time, and oven heating time on the ability of the samples for removal of methyl violet were studied. The obtained activated carbon was characterized by N₂ adsorption/desorption, SAXS, TEM and SEM methods. The adsorption of methyl violet onto the activated carbon was studied from both equilibrium and kinetic point of view and the results were compared with the commercial granular activated carbon. The rate of adsorption onto the prepared activated carbon was faster than commercial activated carbon. Different kinetic models were used to analyze the experimental kinetic data. The obtained activated carbon showed higher adsorption capacity (more than twice) for the adsorption of methyl violet in comparison with the commercial one. The equilibrium data were analyzed using different isotherm models. Adsorption was found to be maximum in the pH range 7-9.     

Regioselective cross-coupling of allylindium reagents with activated benzylic bromides—a simple and efficient procedure for the synthesis of terminal alkenes

Allylindium reagents undergo facile and highly regioselective cross-coupling with benzylic and cinnamyl bromides in THF at room temperature without any catalyst producing terminal alkenes in high yields. The addition is highly regioselective and is found to provide γ-adducts in all reactions.     

Bifunctional chiral phosphine-containing Lewis base catalyzed asymmetric Morita–Baylis–Hillman reaction of aldehydes with activated alkenes

A series of novel bifunctional chiral phosphine-containing Lewis bases were synthesized and successfully applied to the asymmetric Morita–Baylis–Hillman reaction of aldehydes with methyl vinyl ketone (MVK) and ethyl vinyl ketone (EVK) to give the corresponding adducts in moderate yields and enantioselectivities under mild reaction conditions.