Reaction of α,β-unsaturated trifluoromethyl ketones with ethyl cyanoacetate

β-Aryl-substituted α,β-unsaturated trifluoromethyl ketones react with ethyl cyanoacetate to give the corresponding Michael addition products, ethyl 3-aryl-2-cyano-6,6,6-trifluoro-5-oxohexanoates, which are formed as mixtures of two diastereoisomers. The reaction time and product yield depend on electron-donating properties of the substituent in the initial ketone. The reaction is not accompanied by intramolecular cyclization of the Michael adducts.     

Synthesis of trifluoromethyl derivatives of pyrrole. Reaction of α,β-unsaturated trifluoromethyl ketones with sodium cyanide

An efficient preparative procedure was developed for the synthesis of 5-hydroxy-5-trifluoromethyl-2-pyrrolidones by the reaction of ,-unsaturated trifluoromethyl ketones with sodium cyanide. Dehydration of these reaction products under mild conditions afforded previously unknown 5-trifluoromethyl-3-pyrrolin-2-ones.     

Reaction of unsymmetrical α,β-unsaturated ketones with thiobarbituric acid

Carbocyclization of unsymmetrical 1,5-diarylpenta-1,4-dien-3-ones with thiobarbituric acid afforded previously unknown 7,11-diaryl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-triones with high regio- and stereoselectivity. The same spiro compounds were also synthesized by three-component condensation of thiobarbituric acid with the corresponding aromatic aldehydes and 4-arylbut-3-en-2-ones.     

Reaction of dibenzylphosphine oxide with α,β-unsaturated O-methyloximes

The reaction of dibenzylphosphine oxide with O-methyloximes of some ,-unsaturated ketones results in the phosphorylation at the -carbon atom to form methoxyiminophosphine oxides, whereas the reaction of dibenzylphosphine oxide with O-methyloximes of ,-unsaturated aldehydes affords aminodihydrophosphole oxides.     

Regiospecific and diastereoselective aldol reaction of chiral N-sulfinyl metalloenamines with α,β-unsaturated trifluoromethyl ketones: Asymmetric synthesis of tertiary trifluoromethyl allylic carbinols

Regiospecific and diastereoselective aldol type reaction of chiral N-sulfinyl metalloenamines with α,β-unsaturated trifluoromethyl ketones was reported, which affords the corresponding tertiary trifluoromethyl allylic carbinols in high yields with good diastereoselectivities (dr up to 90:10). The reduction of the condensation product 3a with LiBHEt₃ and Catecholborane provides CF₃-substituted syn- and anti-1,3-amino alcohols 5a and 5b in high yields with excellent diastereoselectivities (dr > 99:1).     

Chiral Brønsted acid-catalyzed regio- and enantioselective arylation of α,β-unsaturated trifluoromethyl ketones

The interesting examples of chiral phosphoric acid-catalyzed regio- and enantioselective arylation of α,β-unsaturated trifluoromethyl ketones were reported. The reaction proceeded well and the desired products were obtained in good yields (up to 99%) with moderate to good enantioselectivities (up to 88% ee). Several desired products were obtained with excellent optical purities after a single recrystallization. Subsequent reduction of enantiopure products with NaBH₄ afforded two diastereomers of chiral trifluoromethyl-substituted secondary alcohols with high enantioselectivities (98% ee).     

Ferrocenyl-substituted α,β-unsaturated ketones in synthesis of tetrahydropyrimidinones

Ferrocenyltetrahydropyrimidin-2-ones were prepared by reactions of linear and cyclic ,-unsaturated ketones of the ferrocene series with urea in i-PrOH in the presence of t-BuOK. The structures of the compounds prepared were studied by ¹H and ¹³C NMR and IR spectroscopy, and also by single crystal X-ray diffraction.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1887–1893.Original Russian Text Copyright © 2004 by E. Klimova, Lorez, T. Klimova, Garcia, Hernandez, Ramirez.This revised version was published online in April 2005 with a corrected cover date.     

Lipase-catalyzed kinetic resolution of α,β-unsaturated α′-acetoxy ketones

The lipase-catalyzed kinetic resolutions of the α,β-unsaturated α′-acetoxy ketones 3a,b have been investigated. Of the lipases examined, CAL-B from Candida antarctica (fraction B) has been shown to be an efficient biocatalyst, which may be used effectively in preparative scale reactions.     

Anionic cyclizations of aromatic ester dithioacetals with facially biased α,β-unsaturated ketones

Cyclopent-2-enones bearing a plane-nonsymmetric oxygen function on C-4 reacted efficiently with anions derived from aromatic ester dithioacetals to provide annulated products in a highly diastereoselective fashion. Whereas the anion of a dimethoxy aromatic ester dithiolane more rapidly reacted by an alternative intramolecular pathway, the anion of the corresponding aromatic ester dithiane was suitable for the intermolecular cyclization.     

Enantioselective sulfa-Michael addition of thioacids to α,β-unsaturated ketones with bifunctional organocatalyst

Organocatalytic conjugate addition of thioacids to α,β-unsaturated ketones has been studied in the presence of cinchona alkaloid derived urea catalyst. Both the enantiomers of products are accessible with the same level of enantioselectivity using pseudoenantiomeric quinine/quinidine derived catalysts. The catalytic process provides optically active thioesters with high chemical yields (up to 99%) and useful enantioselectivity (up to 83% ee). The reaction was performed with 1 mol % of catalyst in toluene at room temperature. A transition state model has been proposed to explain the stereochemical outcome of the reaction.     

Reaction of 2-aminopyridines with α, β-unsaturated acids

The reaction of 2-amino- and 2-amino-5-halopyridines with acrylic, methacrylic, and crotonic acids forms N-(2-pyridyl)- and N-(5-halo-2-pyridyl)--alanines and the betaines 2-amino-1-(2-carboxylatoethyl)pyridinium or 3,4-dihydropyrido[1,2-a]pyrimidin-2-ones, or their homologs.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 80–85, January, 1992.     

Cobalt-catalyzed conjugate addition of silylacetylenes to α,β-unsaturated ketones

Catalytic addition of silylacetylenes to α,β-unsaturated ketones proceeded in the presence of a cobalt complex coordinated with a bisphosphine ligand to give high yields of β-alkynylketones.     

DABCO catalyzed dimerization of α,β-unsaturated ketones and nitriles

α,β-Unsaturated ketones dimerize in the presence of catalytic amount of 1,4-diazabicyclo[2.2.2]octane(DABCO) to produce the corresponding 2-methylene-1,5-diketones in good yields. Acrylonitrile provides the corresponding dimerized product.     

Conjugate addition to α,β-unsaturated ketones with mixed lithium triorganozincates

Lithium Triorganozincates of the type RR′₂ZnLi, where R′ = Me and R = n-Bu or sec-Bu, efficiently transfer the R group in a 1,4 fashion to α,β-unsaturated ketones.     

Microwave-assisted organocatalytic enantioselective intramolecular aza-Michael reaction with α,β-unsaturated ketones

An organocatalytic enantioselective intramolecular aza-Michael reaction of carbamates bearing conjugated ketones as Michael acceptors is described. By using 9-amino-9-deoxy-epi-hydroquinine as the catalyst and pentafluoropropionic acid as a co-catalyst, a series of piperidines, pyrrolidines, and the corresponding benzo-fused derivatives (indolines, isoindolines, tetrahydroquinolines, and tetrahydroisoquinolines) can be obtained in excellent yields and enantioselectivities. In addition, the use of microwave irradiation at 60 °C improves the efficiency of the process giving rise to the final products with comparable yields and enantiomeric excesses. Some mechanistic insights are also considered.     

Addition of esters of nitroacetic acid to α,β-unsaturated ketones

Summary The addition reaction of esters of nitroacetic acid to, -unsaturated ketones was studied, and new esters of ketonitroacids were prepared.