Organocatalytic asymmetric direct aldol reactions of trifluoroacetaldehyde ethyl hemiacetal with aromatic methyl ketones

The organocatalytic asymmetric direct aldol reaction of trifluoroacetaldehyde ethyl hemiacetal with aromatic methyl ketones in the presence of a catalytic amount of (S)-5-(pyrrolidin-2-yl)-1H-tetrazole in dichloroethane at 40 °C proceeds smoothly to produce (R)-4,4,4-trifluoro-1-aryl-3-hydroxy-1-butanones in high yields with up to 90% ee.     

3-Oxo-4,4,4-trifluorobutyronitriles as building blocks of trifluoromethyl substituted heterocycles 2. Heterocyclization to 3-aryl-4-trifluoromethyl-2H-1-benzopyran-2-ones under hoesch reaction conditions

Resorcinol and 5-methylresorcinol, respectively, react with 3-oxo-2-aryl-4,4,4-trifluorobutyronitrile using zinc chloride as a catalyst in dibutyl ether under the Hoesch reaction conditions to give a low yield of 3-aryl-7-hydoxy-4-trifluoromethyl- or 3-aryl-5-hydroxy-7-methyl-4-trifluoromethyl-2H-l-benzopyran-2-ones. However, the related reaction with m-methoxyphenol was found to produce poor yields of 3-aryl-7-methoxy-4-trifluoromethyl-2H-1-benzopyran-2-one and its 3,4-dihydro-4-hydroxy derivative.     

Heterocyclizations of functionalized heterocumulenes with C,N-, C,O-, and C,S-binucleophiles: VII. Reaction of 1-chloroalkyl isocyanates with N,N-disubstituted cyanothioacetamides. A new synthetic route to 6-dialkylamino-4-oxo-3,4-dihydro-2<Emphasis Type="Italic">H</Emphasis>-1,3-thiazine-5-carbonitriles

Reactions of α-chlorobenzyl isocyanates and 1-aryl-2,2,2-trifluoro-1-chloroethyl isocyanates with N,N-disubstituted cyanothioacetamides gave 3,4-dihydro-2H-1,3-thiazin-4-ones and 3-aryl-2-cyano-4,4,4-trifluorobut-2-enethioamides. The effect of substituents in the reactant molecules on the reaction course and product ratio was studied.     

Synthesis and hydrogenation of (E)-γ-aryl-γ-morpholino-α-trifluoromethylated allyl alcohols through the reaction of trifluoroacetaldehyde ethyl hemiacetal with enamines

Treatment of trifluoroacetaldehyde ethyl hemiacetal with enamines, derived from acetophenone derivatives, at room temperature gave (E)-1,1,1-trifluoro-4-morpholino-4-aryl-but-3-en-2-ols, which are intermediates for preparation of the β-trifluoromethylated aldol products, 4,4,4-trifluoro-3-hydroxy-1-aryl-butan-1-ones. The structure of the intermediate (E)-1,1,1-trifluoro-4-morpholino-4-(4-nitrophenyl)-but-3-en-2-ols could be assigned by ¹H, ¹³C NMR, IR, and X-ray crystallography. Furthermore, hydrogenation and reductive deamination of the intermediate (E)-1,1,1-trifluoro-4-morpholino-4-aryl-but-3-en-2-ols with hydrogen in the presence of a catalytic amount (10 mol %) of palladium on carbon in trifluoroethanol proceeded smoothly at room temperature to give 1,1,1-trifluoro-4-aryl-2-butanols in good to excellent yields.     

Convenient one-pot synthesis of fluorinated DHPs derivatives and their further transformations

One-pot four-component reactions of aromatic aldehyde, Meldrum’s acid, ethyl-4,4,4-trifluoro-1,3-dioxobutanoate, and ammonium acetate afford ethyl 2-hydroxy-6-oxo-4-aryl-2-(trifluoromethyl)piperidine-3-carboxylate in good yields. The one-pot four-component process consists of an initial Michael addition, and a subsequent intramolecular cyclization. The effect of solvents on the reaction efficiency and yield is briefly investigated. The structure of product is further confirmed by XRD analysis. Meanwhile, the further transformation of hemi-aminal moiety to the corresponding dehydrated product is also achieved under the mild reaction conditions. The possible mechanism for the formation of product is presented.     

Unexpected high regiocontrol in Heck reaction of fluorine-containing electron-deficient olefins—Highly regio- and stereoselective synthesis of β-fluoroalkyl-α-aryl-α,β-unsaturated ketones

Treatment of (E)-4,4,4-trifluoro-1-aryl-2-buten-1-one with various aryldiazonium salts in the presence of palladium catalyst gave the corresponding α-arylated Heck adducts with high regio- and stereoselectivity in good to high yields.     

The synthesis and chemistry of 2-hydroxy-4,6-bis(trifluoromethyl)pyridine-5-carboxylates

The facile two step, one pot synthesis of heretofore unknown 2-hydroxy-4,6-bis(trifluoromethyl)-pyridine-5-carboxylates by condensation of 3-amino-4,4,4-trifluoro-2-butenoate with 4,4,4-trifluoroacetoacetyl chloride and subsequent intramolecular cyclization of the resultant enamineamide is described. Methodology for the introduction of electrophiles at the 3-position and elaboration of substituents at the 2- and 5-positions is also discussed.     

Ethyl 2-(α-hydroxyhexafluoroisopropyl)acrylate as a potential precursor of fluorine- and sulfur-containing CH-acids

The reactivity of ethyl 2-(α-hydroxyhexafluoroisopropyl)acrylate (1) was studied. The addition of thioacetic acid to compound1 occurs at 20°C, while reactions with thiols proceed only at 120°C and are accelerated in the presence of an acid catalyst. Dealkylation of acrylate1 with iodotrimethylsiliane affords 4,4,4-trifluoro-3-hydroxy-2-iodomethyl-3-trifluoromethylbutyric acid, which served as the starting compound for the synthesis of 3-chloro-4,4,4-trifluoro-2-iodomethyl-3-trifluoromethylbutyroyl chloride, a potential precursor of alicyclic fluorine- and sulfur-containing CH-acids.     

Reaction of 2 -methyl-2-cinnamoyloxiranes with benzylamine and thioacetic acid

Reaction of 2-methyl-2-cinnamoyloxiranes with benzylamine gave stereoisomeric 3-hydroxy-3-methyl-1-benzyl-6-aryl-4-piperidones, which were converted to 3-hydroxy-1,3-dimethyl-6-aryl-4-piperidones by debenzylation and subsequent methylation. 3-Hydroxy-3-methyl-6-phenyltetrahydro-4-thiopyrone acetate was obtained by reaction of 2-methyl-2-cinnamoyloxirane with thioacetic acid. The three-dimensional configurations of the synthesized compounds were established by means of their IR and PMR spectra.     

Five-membered 2,3-dioxo heterocycles: LXXXIX. Reaction of methyl 1-aryl-3-cinnamoyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates with (E)-4-arylaminopent-3-en-2-ones. Crystalline and molecular structure of 9-acetyl-4-cinnamoyl-3-hydroxy-1-(4-methoxyphenyl)-8-methyl-7-phenyl-1,7-diazaspiro[4.4]nona-3,8-diene-2,6-dione

Methyl 1-aryl-3-cinnamoyl-4,5-dioxo-4,5-dihydro-1H-pyrrole-2-carboxylates reacted with 4-benzylamino- and 4-arylaminopent-3-en-2-ones to give 1-aryl-7-benzyl- and 1,7-diaryl-9-acetyl-4-cinnamoyl-3-hydroxy-8-methyl-1,7-diazaspiro[4.4]nona-3,8-diene-2,6-diones. The crystalline and molecular structures of 9-acetyl-4-cinnamoyl-3-hydroxy-1-(4-methoxyphenyl)-8-methyl-7-phenyl-1,7-diazaspiro[4.4]nona-3,8-diene-2,6-dione were studied by X-ray analysis.     

2-Polyfluoroalkylchromones. 6. Synthesis of substituted 2-morpholino-2-trifluoromethylchroman-4-ones

Morpholine adds smoothly at the double bond of substituted 5- and 8-nitro-2-trifluoromethylchromones to form the corresponding 2-morpholino-2-trifluoromethylchroman-4-ones. 6-Methoxy-5-nitro-2-trifluoromethylchromone adds also benzylamine, whereas 7-methoxy-8-nitro-2-trifluoromethylchromone undergoes ring opening under the action of benzylamine to give 3-benzylamino-4,4,4-trifluoro-1-(2-hydroxy-4-methoxy-3-nitrophenyl)but-2-en-1-one.     

Highly diastereoselective multicomponent synthesis of polysubstituted 2-hydroxy-2-trifluoromethylpiperidineswith four and five stereogenic centers

The Michael–Mannich cascade cyclization of cyano olefins, ethyl 4,4,4-trifluoro-3-oxobutanoate, aromatic aldehydes and ammonium acetate provides convenient stereoselective formation of ethyl 5,5-dicyano-4,6-diaryl-2-hydroxy-2-(trifluoromethyl)piperidine-3-carboxylates with fourstereogenic centers and dialkyl 4,6-diaryl-5-cyano-2-hydroxy-2-(trifluoromethyl)piperidine-3,5-dicarboxylates with five stereogenic centers. Ammonium acetate plays dual role, acting as a base and as a nitrogen source.     

Cycloaddition of 1-Aryl-3-trimethylsiloxy-1,3-butadienes in the Synthesis of Natural Quinone Analogs

7-Hydroxy-5-(2-methoxyphenyl)-2-methyl-6-R-1,4-naphthoquinones, 8-hydroxy-1-(2-methoxyphenyl)-3-oxo-1,2,3,4-tetrahydro-9,10-anthraquinone, and 2-ethoxycarbonyl-8-hydroxy-1-(2-methoxyphenyl)-3-trimethylsiloxy-1,1a,4,4a-tetrahydro-9,10-anthraquinone were synthesized by reactions of 1-(2-methoxyphenyl)-2-R-3-trimethylsiloxy-1,3-butadienes with 2-bromo-5-methyl-1,4-benzoquinone and juglone. 1-Aryl-2-ethoxycarbonyl-3-trimethylsiloxy-1,3-butadienes reacted with 1,4-naphthoquinone to afford 1-aryl-2-ethoxycarbonyl-3-hydroxy-9,10-anthraquinones and their 4,4a-dihydro derivatives.     

Preparation of trifluoromethylated pyrazoles and 1,4-thiazine 1,1-dioxides from trifluoromethylated sulfone derivatives

Trifluoromethylated sulfones, 3-amino-2-arylsulfonyl-4,4,4-trifluoro-3-hydroxybutanenitrile ( 3 ) and 3-(aroylmethyl)sulfonyl-1,1,1-trifluoropropane-2,2,-diols 12 , were prepared and cyclized to 4-arylsulfonyl-5-trifluoromethyl-3-hydrazinopyrazoles 9 and 5-arylsulfonyl-3-trifluoromethyl-3-hydroxy-2,3-dihydro-4H-1,4-thiazine 1,1-dioxides 13 , respectively.     

Derivatives of 4-hydroxy-5,6,7,8-tetrafluorocoumarin in reactions with o-aminothiophenol

The derivatives of 4-hydroxy-5,6,7,8-tetrafluorocoumarin in reactions witho-aminothiophenol yield products of S-substitution at C⁷ atom, 7-substituted 5,6,8-trifluorocoumarins afford benzothiazoles as a result of cleavage of the pyrone cycle, 2-methyl-3-ethoxycarbonyl-5,6,7,8-tetrafluorochromone undergoes acidic cleavage to 2-(2-hydroxy-3,4,5,6-tetrafluorophenyl)benzothiazole. S-Substituted coumarins in alkaline media suffer decomposition to acetophenone. In acidic media 3-iminoacetyl-4-hydroxy-5,6,8-trifluoro-7-(2-aminophenylthio)coumarin affords 2-methyl-5,6,8-trifluoro-7-(2-aminophenylthio)chromone. In condensation of 4-hydroxy-5,6,8-trifluoro-7-(2-aminophenylthio)coumarin in the presence of NaH was isolated 4-hydroxy-5,6-difluoro-2H-pyrano[6,5-a]phenothiazin2-one.     

Five-membered 2,3-dioxoheterocycles: XC. Reaction of 4,5-bis(methoxycarbonyl)-1H-pyrrole-2,3-diones with enaminoesters. crystal and molecular structure of 4-methyl 9-ethyl 7-benzyl-3-hydroxy-8-methyl-1-(4-methoxyphenyl)-2,6-dioxo-1,7-diazaspiro[4.4]nona-3,8-diene-4,9-dicarboxylate

1-Aryl-4,5-bis(methoxycarbonyl)-1H-pyrrole-2,3-diones react with ethyl 3-(benzylamino)but-2-enoate and ethyl 3-(benzylamino)-3-phenylacrylate giving 4-methyl 9-ethyl 1-aryl-7-benzyl-3-hydroxy-8-methyl- and 4-methyl 9-ethyl 1-aryl-7-benzyl-3-hydroxy-8-phenyl-2,6-dioxo-1,7-diazaspiro[4.4]nona-3,8-diene-4,9-dicarboxylates.     

THE BAYLIS—HILLMAN REACTION: TiCl4 MEDIATED COUPLING OF ALKYL VINYL KETONES WITH α-KETO ESTERS AND ALDEHYDES

TiCl₄ mediated coupling of alkyl vinyl ketones with α-keto esters and aldehydes provides respectively 2-aryl-2-hydroxy-3-methylene-4-oxoalkanoates and (Z)-keto allyl chlorides in 1 h time at room temperature. Similar coupling of trifluoromethyl phenyl ketone with methyl vinyl ketone produces 1,1,1-trifluoro-2-hydroxy-2-phenyl-3-methylenepentan-4-one.     

Applying density functional theory on tautomerism in 3,4-dihydropyrimidin-2(1H)-ones

In the present study, the density functional theory (DFT) and Gibbs free energy calculations were performed to investigate the stability and tautomerism of C4-substituted-3,4-dihydropyrimidin-2(1H)-ones. Three different forms are possible for the ethyl 3,4-dihydropyrimidinones (ethyl 4-aryl-6-methyl-3,4-dihydropyrimidin-2(1H)-one-5-carboxylates, ethyl 4-aryl-2-hydroxy-6-methyl-1,4-dihydropyrimidine-5-carboxylates and ethyl 4-aryl-2-hydroxy-6-methyl-3,4-dihydropyrimidine-5-carboxylates) forms that the most stable form is ethyl 4-aryl-6-methyl-3,4-dihydropyrimidin-2 (1H)-one-5-carboxylates (keto-form). The obtained data showed that the substitution on the C4-substitut position can be effective on the equilibrium constant (K _eq).     

2-Polyfluoroalkylchromones. 8. 2-Trifluoromethyl- and 6-nitro-2-trifluoromethylchromones in reactions with amines

The reactions of 6-nitro-2-trifluoromethylchromone with benzylamine, ethanolamine, and aniline afforded 3-benzyl(2-hydroxyethyl,phenyl)amino-4,4,4-trifluoro-1-(2-hydroxy-5-nitrophenyl)but-2-en-1-ones, respectively, whereas the reactions with ethylenediamine and diethylenetriamine gave rise to 5-(2-hydroxy-5-nitrophenyl)-7-trifluoromethyl-2,3-dihydro-1H-1,4-diazepine and 5-(2-hydroxy-5-nitrophenyl)-7-trifluoromethyl-1,4,8-triazabicyclo[5.3.0]dec-4-ene, respectively. Morpholine added at the double bond of 2-trifluoromethyl- and 6-nitro-2-trifluoromethylchromones to form 2-morpholino-2-trifluoromethylchroman-4-one and its 6-nitro-substituted analog, respectively, whereas piperidine reacted only with 2-trifluoromethylchromone to yield 2-piperidino-2-trifluoromethylchroman-4-one.     

Synthesis and luminescent properties of neutral Eu(III) and Gd(III) complexes with 1-(1,5-dimethyl-1h-pyrazol-4-yl)-4,4,4-trifluoro-1,3-butanedione and 4,4,5,5,6,6,6-heptafluoro-1-(1-methyl-1H-pyrazol-4-yl)-1,3-hexanedione

Neutral [EuL₃Phen] complexes were synthesized by the reaction of EuCl₃ with heterocyclic diketones-1-(1,5-dimethyl-1H-pyrazol-4-yl)-4,4,4-trifluoro-1,3-butanedione and 4,4,5,5,6,6,6-heptafluoro-1-(1-methyl-1H-pyrazol-4-yl)-1,3-hexanedione—and 1,10-phenanthroline (Phen) in an aqueous alcohol solution in the presence of NaOH. The reaction of GdCl₃ with the same diketones under analogous conditions, but without adding 1,10-phenanthroline, yielded [GdL₃(H₂O)₂] complexes. The composition of the complexes was determined by elemental analysis, and their optical and luminescent properties were examined.