A new regio- and stereoselective synthesis of β-enamino ketones with 3-ethoxycyclobutanones and substituted amines

A new method toward regio- and stereoselective synthesis of β-enamino ketones is described. Through Lewis acid-catalyzed reactions between 3-ethoxycyclobutanones and substituted amines, a variety of cis and trans β-enamino ketone derivatives were prepared with complete regio- and stereoselectivity at room temperature.     

Oxiranyl β-aminovinyl ketones. 5. Transformation of 2-methyl-2-(1-halogenoalkyl)-3(2h)-furanones into oxiranyl β-aminovinyl ketones

In reaction with amines 2-methyl-2-(1-halogenoalkyl)-3(2H) furanones form S-amino-1-halogeno-3-hydroxy-2-methyl-4 penten-3-ones and 6-amino-2-halogeno-3-hydroxy-3-methyl-5-hexen-3-ones, which are converted by the action of bases into the corresponding oxiranyl -aminovinyl ketones.Belorussian State University, Department of Organic Chemistry and Chemistry of High-Molecular Compounds, Minsk. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 609-612, May, 1995. Original article submitted April 11, 1995.     

Chemoselective cross-coupling of terminal propargylamines with (het)aroyl chlorides: synthesis of β-aminoacetylenic ketones bearing aromatic and heteroaromatic substituents

Russian Chemical Bulletin - Terminal secondary 4-chlorophenyl propargylamines, synthesized by addition of acetylene to N-(4-chlorophenyl)ketimines (ButOK, DMSO, 20–25 °C) in 76–93%...     

Metal-free synthesis of (E)-vinyl sulfones via denitrative coupling reactions of β-nitrostyrenes with sodium sulfinates

Abstract

A practical metal-free procedure for the synthesis of (E)-vinyl sulfones has been developed through the coupling of β-nitrostyrenes with sodium sulfinates under microwave irradiation. This methodology provides a convenient and efficient approach to various (E)-vinyl sulfones from readily available starting materials with excellent regioselectivity. The present oxidative reaction involves an efficient denitrative radical cross-coupling of β-nitrostyrenes with sodium sulfinates via using AcOH as an additive.     

A facile synthesis of 3-hydroxy-3-(trifluoromethyl)-1H-pyrrol-2(3H)-ones with Brønsted acid-catalyzed condensation–cyclization reactions of β-enamino esters and ethyl trifluoropyruvate

A facile synthesis of 3-hydroxy-3-(trifluoromethyl)-1H-pyrrol-2(3H)-ones based on trifluoroacetic acid-catalyzed condensation–cyclization reactions of β-enamino esters and ethyl trifluoropyruvate is described. These reactions afford a series of α-trifluoromethylated γ-lactam compounds in good to excellent yields under mild conditions. A preliminary trial of an asymmetric catalytic version with chiral BINOL-derived phosphoric acid as enantioselective catalyst was conducted and showed promising enantioselectivity of the desired product.     

Simple and efficient synthesis of racemic 2-(tert-butoxycarbon-ylamino)-2-methyl-3-(1H-1,2,4-triazol-1-yl)propanoic acid, a new derivative of β-(1,2,4-triazol-1-yl)alanine

A simple synthetic approach to racemic N-tert-butyloxycarbonyl-2-methyl-3-(1H-1,2,4-triazol-1-yl)alanine (5) in four steps and 68% overall yield starting from oxazoline derivative 1 is reported. This synthesis involves the alkylation of 1H-1,2,4-triazole with an O-tosyloxazoline derivative, followed by an oxazoline ring-opening reaction and oxidation of the N-protected β?aminoalcohol by potassium permanganate.     

Synthesis of Fluoroalkylated Heterocycles via the Reaction of 3-(1-Hydropolyfluoroalkenyl)-1-oxo-2,4,1-benzoxazines with Dinucleophilic Reagents

The reaction of 3-(1-hydropolyfluoroalkenyl)-1-oxo-2,4,1-benzoxazines 1 with some dinucleophiles was inves-tigated.7-Fluoroalkyl-2,3-dihydro-1,4-diazepine[1,2-d]quinazolin-11-ones 2,2-fluoroalkylisoxazolo[3,2-b]quin-azolin-9-ones 3 and 2-fluoroalkylbenzoimidazoles 4 were obtained from the reaction of 1 with 1,2-diaminoethane,hydroxylamine hydrochloride and 1,2-diaminobenzene respectively.     

A new synthesis of γ-butyrolactones via AuCl(3)- or Hg(II)-catalyzed intramolecular hydroalkoxylation of 4-bromo-3-yn-1-ols

An efficient conversion of 4-bromo-3-yn-1-ols to γ-butyrolactones via AuCl(3)-catalyzed electrophilic cyclization (hydroxyl-assisted regioselective hydration) in wet toluene is described. Various secondary and tertiary alcohols including benzylic systems were found to be equally reactive with moderate to excellent yields obtained in all cases.     

Opening of the pyridine ring in the system 1,1,1-trifluoro-4-phenylbut-3-yn-2-one–water. Stereoselective synthesis of 5-{[(1Z)-4,4,4-trifluoro-3-oxo-1-phenylbut-1-en-1-yl]amino}penta-2,4-dienal

Russian Journal of Organic Chemistry -     

Crystal Structure of Methyl 3- (2-chlorophenyl )-3- (5, 5-dimethyl-3-hydroxy-2-cyclohexene- 1-one-2-yl) propionate

1INTRODUCTIONInorganicsolidsupportsascatalystshavebeenwellstudied,becauseoftheirap-plicationsinorganicsynthese('~".Recently,wehavereportedtheKnoevenagelcon-densationcatalysedbyKF-Al,O,['i.Inthispaper,wediscussedthecrystalstruc-tureofthetitlecomPoundsynthesizedbythereactionof2-chlorobenzaldehydey5,5-dimethyl-1,3-cyclohexanedioneandisopropylidenemalonateinmethanolcatalyzedbyKF-Alzo,'Inordertoconfirmthestructureofthetitlecompound,theX-raycrys-tallOgraphicstudywascarriedout.2EXPER1MEN…     

Reactions of Methyl 1-(Bromoacetyl)azulene-3-carboxylate with 2-Hydroxy-benzaldehydes: Synthesis of 1-(Benzofuran-2-yl)-3- methoxycarbonylazulenes

A few compounds containing the 2-arylbenzofuran nucleus, have been isolated from plants.[1] For example,moracins A and B, egonol, homoegonol and (±)-machicendiol are well known.     

Synthesis of 2-(trifluoromethyl)oxazoles from β-monosubstituted enamines via PhI(OCOCF3)2-mediated trifluoroacetoxylation and cyclization

Treatment of β-monosubstituted enamines with phenyliodine bis(trifluoroacetate) (PIFA) was found to give a variety of 4,5-disubstituted 2-(trifluoromethyl)oxazoles. This approach allows the incorporation of the trifluoromethyl moiety in PIFA into the final products, which presumably takes place via the oxidative β-trifluoroacetoxylation of the enamine substrates followed by subsequent intramolecular cyclization.     

FeCl3·6H2O catalyzed diastereoselective synthesis of (L)-menthyl 4-oxo-2-arylpiperidine-3-carboxylates

An efficient diastereoselective synthesis of substituted piperidines is accomplished by using catalytic amount of FeCl₃·6H₂O via intramolecular aza-Michael addition of carbamate on alkylidene β-keto (L)-menthyl esters in a very short time.     

Sonogashira reactions of α- and β-1-ethynyl-2-deoxyribosides: synthesis of acetylene-extended C-nucleosides

An improved practical protocol for the synthesis of both anomers of 1-ethynyl-2-deoxiribosides 1 was developed. The Sonogashira coupling of ethynyldeoxyribosides 1 with various aryl- and heteroaryl halides was carried out under various conditions. It was found that the use of copper-free coupling protocols could reduce the oxidative dimerisation in favour of arylalkynyldeoxyriboside formation.     

Investigation of supramolecular inclusion complexes with β-cyclodextrin of 1-(2-ethoxyethyl)-4-(pentyn-1-yl)-4-hydroxypiperidine and 1-(2-ethoxyethyl)-4-(pentyn-1-yl)-4-benzoyloxypiperidine oxalate by NMR spectroscopy

A comparative analysis of ¹H and ¹³C NMR spectra of 1-(2-ethoxyethyl)-4-(pentyn-1-yl)-4-hydroxypiperidine, 1-(2-ethoxyethyl)-4-(pentyn-1-yl)-4-benzoyloxypiperidine oxalate and their inclusion complexes with β-cyclodextrin was performed. The differences in values of chemical shifts of ¹H and ¹³C nuclei of the substrates and the receptor in the inclusion complexes were determined. It was found that the formation of complexes of 1-(2-ethoxyethyl)-4-(pentyn-1-yl)-4-hydroxypiperidine and 1-(2-ethoxyethyl)-4-(pentyn-1-yl)-4-benzoyloxypiperidine oxalate with β-cyclodextrin was accompanied by insertion of one N-ethoxyethyl fragment of the substrate molecule into the inner sphere of one molecule of the receptor.     

One-pot synthesis of 4,4-difluoro-3-oxo-2-(triphenylphosphoranylidene)-δ-lactones by Reformatsky reaction

In th presence of zinc and a catalytic amount of cuprous chloride, ethyl 4-bromo-4,4-difluoro-3-oxo-2-(triphenylphosphoranylidene)butanoate 1 reacted with carbonyl compounds to give the gem-difluoromethylenated 2-(triphenylphosphoranylidene)-δ-lactones 4 in moderate to high yields.     

Bi(OTf)3 catalyzed synthesis of acyclic β-sulfanyl ketones via a tandem Meyer-Schuster rearrangement/conjugate addition reaction

A new strategy to prepare acyclic β-carbonyl thioethers from propargyl alcohols and sulfur nucleophiles is reported. The investigation of the reaction substrates scope indicated that primary 3-aryl propargyl alcohols and thiols underwent the transformation smoothly. The reaction probably proceeded a Bi(OTf)₃-catalyzed tandem Meyer-Schuster rearrangement of 3-aryl propargyl alcohol, followed by a thiol Michael conjugate addition of thiols to in situ generated α, β-unsaturated ketones. The method was 100% atom economic, high-yielding, and easy to handle, making it a valuable method for the construction of β-carbonyl sulfides.     

Reaction of N′-(Arylmethylidene)-2-oxo-2H-chromene-3-carbohydrazides with Methyl 1-Bromocycloalkanecarboxylates and Zinc

Russian Journal of General Chemistry - Depending on the ring size in the Reformatsky reagent and the nature of substituents in arylmethylidene fragment, the reactions of Reformatsky reagents...