Addition reactions of 1,1,1-trifluoro-4-trimethylstannylbut-3-yn-2-one and 1,1,1-trifluorobut-3-yn-2-one to some tetrahydropyridines. Synthesis of trifluoroacylated polysubstituted tetrahydroazocines

A reaction of tetrahydropyridines, obtained by the Diels-Alder reaction from α,β-unsat-urated N,N-dimethylhydrazones and methyl acrylate, with acetylenes activated with the trifluoroacetyl group has been studied and found to lead to polysubstituted trifluoroacylated tetrahydroazocines. No cyclobutene intermediates have been detected.     

The reaction of 1-phenylbut-1-yn-3-one with furan aldehydes

The crotonic condensation of 5-bromo-, 5-iodo-, and 5-nitrofur-furals with 1-phenylbut-1-yn-3-one has been effected.     

Light-induced reactions of 1,1,1-trifluoro-3-decyn-2-one with olefins

Irradiation ( λ = 300 nm) of 1,1,1-trifluoro-3-decyn-2-one in the presence of olefins affords RH-reduction products (tertiary alcohols) in addition to [2+2] -(oxetans) and [3+2] -(dihydrofurans) cycloadducts.     

Study on the 1,3-dipolar cycloaddition reaction of 4-ethoxy-1,1,1-trifluoro-3-buten-2-one with nitrile oxides

1,3-Dipolar cycloaddition (1,3-DC) reaction of 4-ethoxy-1,1,1-trifluoro-3-buten-2-one 1 with nitrile oxides was studied. It was found that besides its CC participating in the formation of isoxazole rings, trifluoromethyl activated CO also underwent 1,3-DC reaction with nitrile oxides to afford 1,4,2-dioxazole rings. Single crystal diffraction analysis also evidenced the diheterocyclic configuration.     

Synthesis Of CF3-Heterocycles Based on 4-Dimethylamino-1,1,1-trifluoro-3-buten-2-one

Novel heterocyclizations have been investigated based on the reaction of the complex between trifluoromethanesulfonic anhydride and 4-dimethylamino-1,1,1-trifluoro-3-buten-2-one with 2,2'-biindolyl and N,N'-dipyrrolylmethane leading to closure of 6- or 7-membered rings.     

4-Halogeno-1,1,1-trifluorobut-3-yn-2-one [4+2] cycloadducts and their cross-coupling with organozinc compounds

The reactions of 4-chloro-1,1,1-trifluorobut-3-yn-2-one and 4-bromo-1,1,1-trifluorobut-3-yn-2-one with conjugated dienes afford [4+2] cycloadducts in high yields. The halogen atom in the products is readily replaced by a (het)aryl residue in the cross-coupling with organozinc compounds.     

Unexpected transformation of 3-amino-4,4,4-trifluoro-1-phenylbut-2-en-1-one into 2,6-diphenyl-4-trifluoromethylpyridine

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[2+2] Cycloaddition and electrophilic alkynylation reactions of 4-chloro-1,1,1-trifluorobut-3-yn-2-one and alkyl vinyl ethers

Reaction of 4-chloro-1,1,1-trifluorobut-3-yn-2-one with alkyl vinyl ethers leads to the parallel formation of [2+2] cycloaddition and electrophilic alkynylation products, the ratio of which depends on the nature of vinyl ether. Preparative methods for the separation of compounds formed are suggested.     

LDA-mediated domino carbolithiation reactions of vinylidenecyclopropanes with but-3-yn-2-one and 1-phenylprop-2-yn-1-one

A novel domino carbolithiation reaction of vinylidenecyclopropanes 1 with but-3-yn-2-one and 1-phenylprop-2-yn-1-one by treating with LDA in THF was observed to give the corresponding adducts in moderate to good yields. The scope and limitations as well as the plausible mechanism have been discussed on the basis of control experiments.     

Oxidative Cyclization of Lithium 4-Ethoxy-1,1,1-trifluoro-4-oxobut-2-en-2-olate

Russian Journal of Organic Chemistry - Diethyl 2,5-dihydroxy-2,5-bis(trifluoromethyl)tetrahydrofuran-3,4-dicarboxylate has been synthesized for the first time by reaction of lithium...     

Crystal structures of 1,1,1-trifluoro-4-hydroxy-4-phenyl-but-3-en-2-one, 2,2,6,6-tetramethyl-3-hydroxy-hept-3-en-5-one, 2,2,6,6-tetramethyl-3-methylamino-hept-3-en-5-one and a study of the ability of these ligands to complex formation with metals

Crystal structures are determined (Bruker Nonius X8 Apex, 4K CCD-detector, λMoK _α, graphite monochromator, T 150 K and 293 K) for two β-diketones F₃CC(O)CH₂C(O)Ph (1) (space group P2₁/c, a = 7.0713(3)Å, b = 11.5190(6)Å, c = 11.3602(6) Å, β = 99.405(2)°, V = 912.90(8) ų, Z = 4), (CH₃)₃CC(O)CH₂C(O)C(CH₃)₃ (2) (space group Pbca, a = 11.5536(8) Å, b = 11.5796(10) Å, c = 17.2523(13) Å, V = 2308.1(3) ų, Z = 8) and a ketoimine (CH₃)₃CC(NCH₃)CH₂C(O)C(CH₃)₃ (3) (space group I4₁/a, a = 18.7687(6) Å, b = 18.7687(6) Å, c = 14.5182(6) Å, V = 5114.2(3) ų, Z = 16). All structures are molecular and comprise isolated molecules joined by van der Walls interactions. The substitution energy of a Na atom for a hydrogen atom in free ligands is calculated by the hybrid B3LYP quantum chemical method. A successful preparation of Na(I) chelates with ligands 1, 2 and failed attempts to prepare a complex with ligand 3 are in accordance with the calculations. Geometrical simulation of a copper(II) complex with ligand 3 reveals the overlap of CH₃ groups which hinders the complexation.     

Synthesis and transformations of 1,1,1-trifluoro-2-benzylthiopropene

Conclusions 1,1,1-Trifluoro-2-benzylthiopropene was synthesized and the reactions of this sulfide with electrophiles and nucleophiles (H₂SO₂, SO₂C₁₂ and NHEt₂) leading 1,1,1-trifluoroacetone, 1,1,1-trifluoro-2,3-dichloro-2-benzylthiopropane and 1-trifluoromethy1-2-(N,N-diethylamino)-ethyl benzyl sulfide, respectively, were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 209–211, January, 1987.     

Synthesis of 1,1,1 - trifluoro-2-penten-4-one

The 1,1,1-trifluoro-2-penten-4-one has been prepared from trifluoroacetaldehyde by two different ways. Its condensation with a cyclohexanone enamine leads, by annelation, to 4-trifluoromethyl-Δ-1,9 (and Δ-9,10)-octalin- 2-one.     

The photochemical Wolff rearrangement of 3-diazo-1,1,1-trifluoro-2-oxopropane revisited

Ethyl 2-diazo-4,4,4-trifluoroacetoacetate (1a) and 3-diazo-1,1,1-trifluoro-2-oxopropane (1b) exhibit a deviating behavior in solution photolysis (hydrogen abstraction for 1a; Wolff rearrangement for 1b) [(a) F. Weygand, W. Schwenke and H. J. Bestmann, Angew. Chem., 1958, 70, 506; (b) F. Weygand, H. Dworschak, K. Koch and S. Konstas, Angew. Chem., 1961, 73, 409]. As shown by 13C-labelling of 1b this difference is not caused by rearrangement of the primarily formed alpha-oxocarbene to an isomeric alpha-oxocarbene presenting a hydrogen atom as a migrating substituent for the Wolff rearrangement. It is discussed that the singlet alpha-oxocarbene generated from 1a rapidly undergoes spin equilibration followed by hydrogen abstraction of the triplet alpha-oxocarbene. In contrast, due to a larger singlet-triplet splitting in the singlet alpha-oxocarbene generated from 1b, the intramolecular Wolff rearrangement on the singlet surface can efficiently compete with the singlet-triplet interconversion.     

High-vacuum pyrolysis of 1,1,1-trifluoro-2-bromo-2-chloroethane. IR spectrum of 1,1,1-trifluoro-2-chloroethyl radical in an argon matrix

The products of high-vacuum pyrolysis of 1,1,1-trifluoro-2-bromo-2-chloroethane were studied by matrix IR spectroscopy. The decomposition of 1,1,1-trifluoro-2-bromo-2-chloroethane was shown to occur predominantlyvia two directions: to form the 1,1,1-trifluoro-2-chloroethyl radical and trifluoromethylcarbene isomerizing to trifluoroethylene. The CF₃CHCl radical has been detected in the matrix for the first time. The bands observed in the IR spectrum were calculated by the quantum-chemical B3LYP/6-311 G(d,p) method and assigned to normal vibrations of the radical. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2085–2088, October, 1998.     

Reactions of tri- and hexafluoroacetylacetones and 4-ethoxy-1,1,1-trifluorobut-3-en-2-one with 2-aminobenzohydrazide

Reactions of 1,1,1-trifluoropentane-2,4-dione and 1,1,1,5,5,5-hexafluoropentane-2,4-dione with 2-aminobenzohydrazide afforded (2-aminophenyl)[5-hydroxy-3-methyl-5-(trifluoromethyl)- and (2-aminophenyl)[ 5-hydroxy-3,5-bis(trifluoromethyl)-4,5-dihydropyrazol-1-yl]methanones, respectively. 4-Ethoxy-1,1,1- trifluorobut-3-en-2-one reacted with 2-aminobenzhydrazide to give 2-(trifluoromethyl)-3a,4-dihydropyrazolo-[5,1-{ptb}]quinazolin-9(3{ptH})-one.     

Synthesis of 2-pyridones, pyrimidines, and pyrazoles from 1,1,1-trifluoro-4,4-bis(methylthio)but-3-en-2-one

Reactions of 1,1,1-trifluoro-4,4-bis(methylthio)but-3-en-2-one with cyanoacetamide, malonamide, acetoacetamide, amidines, hydrazines, and hydroxylamine gave a number of novel trifluoromethylated heterocyclic compounds containing the methylthio group.     

Reaction of 1,5-Diphenyl-1,4-pentadien-3-one and 1,5-Diphenyl- 1-penten-4-yn-3-one with Monosubstituted Hydrazines

Phenyl- and isopropylhydrazines react with 1,5-diphenyl-1,4-pentadien-3-one to give 4,5,6,7-tetrahydroindazole derivatives instead of the expected 4,5-dihydropyrazoles. The reaction of phenylhydrazine with 1,5-diphenyl-1-penten-4-yn-3-one leads to formation of 1,5-diphenyl-3-phenylethynyl-4,5-dihydropyrazole. 2,4-Dinitrophenylhydrazine reacts with 1,5-diphenyl-1-penten-4-yn-3-one, affording the corresponding unsaturated hydrazone rather than pyrazole derivative.     

Solvent effects on the O NMR chemical shifts of 4-dimethylsulfoximide-1,1,1-trifluoro-3-alken-2-ones

A multi-linear-regression analysis using the Kamlet-Abbout-Taft (KAT) solvatochromic parameters in order to elucidate and quantify the solvent effects on the chemical shifts of three 4-dimethylsulfoximide-1,1,1-trifluoro-3-buten-2-ones is reported. The predominant conformational structures of compounds has been determined by energy minimization calculations using the Austin Model (AM1) semi-empirical method, which has been used to explain the NMR chemical shifts for CO and SO groups. The chemical shifts of carbonyl and sulfoximide oxygen’s of molecules showed similar dependencies (in ppm) on the solvent polarity-polarizability and the solvent hydrogen-bond-donor (HBD) acidities. The influence of solvent hydrogen-bond-acceptor (HBA) basicities was little significant.