Sterically hindered 1,3-diketones in the Michael reaction

The base catalyzed addition of sterically hindered 1,3-diketones to the activated multiple bond of ethyl acrylate and 4-methyl-4-methoxy-1-phenylpent-2-yne-1-one has been studied. The addition of methyl(2-propenyl)ketone is partially accompanied by intramolecular cyclization of the resulting adduct.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 147–149, January, 1996.     

Iridium-catalyzed reaction of enones with alcohols affording 1,3-diketones

An iridium-catalyzed coupling reaction of alcohols with enones has been successfully developed providing access to 1,3-diketones with high selectivity in good yields. This reaction provides an atom-economical route to 1,3-diketones from readily available alcohols.     

Observation of 1,3-diketones formation in the reaction of bulky acyl chlorides with methyllithium

The formation of 1,3-diketones was observed in the reactions of bulky acyl chlorides with methyllithium. The reaction products depend on the steric hindrance around the carbonyl group of the acyl chloride and the electronic effect of the group(s) linked to the carbonyl. When the steric hindrance around the carbonyl group of the acyl chloride is big enough, the 1,3-diketone is the only product. In the case of the moderate hindrance around the carbonyl group of the acyl chloride, a moderate yield of 1,3-diketone is obtained and some tertiary alcohol is generated. When there is no steric hindrance around the carbonyl group of the acyl chloride, the tertiary alcohol is the only product. When the steric hindrance around the carbonyl group is moderate and an electron-donating group is connected to the carbonyl of the acyl chloride, all three products--ketone, 1,3-diketone and tertiary alcohol--can be isolated from the reaction mixture after long reaction times.     

Regioselection in the reaction of 3-amino-5-benzylthio-1,2,4-triazole with unsymmetrical 1,3-diketones

The results of a study of the regioselection in the reaction of 3-amino-5-benzylthio-1,2,4-triazole with several unsymmetrical 1,3-diketones are reported. The 1,3-diketones studied are 1,1,1-trifluoro-2,4-pentanedione, benzoylacetone and 2-acetylcyclopentanone. Chemical, spectroscopic and X-ray crystallographic data are presented to support structural assignments of the major reaction products.     

Structure of the products of the reaction of 5,6-diamino-1,3-dimethyluracil with 1,3-diaryl-2, 3-dihalopropanones

The reaction of 5,6-diamino-1,3-dimethyluracil with ,-dihalopropanones gives only-(5-amno-6-amino-1,3-uracil)chalcones. Anx-ray diffraction structural analysis was carried out for one of these products.Kharkov State University, 310077 Kharkov and A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 551–557, April, 1995. Original article submitted February 1, 1995.     

Synthesis of 1,2,3,4-tetrasubstituted pyrrole derivatives via the palladium-catalyzed reaction of 1,3-diketones with methyleneaziridines

The palladium-catalyzed reaction of 1,3-diketones 2 with methyleneaziridines 1 produced the corresponding 1,2,3,4-tetrasubstituted pyrroles 3 in good to high yields.     

Iron-promoted C-C bond cleavage of 1,3-diketones: a route to 1,2-diketones under mild reaction conditions

A conceptual method for the preparation of 1,2-diketones is reported. The selective C-C bond cleavage of 1,3-diketones affords the 1,2-diketones in high yields under mild reaction conditions in air by the use of FeCl(3) as the catalyst and tert-butyl nitrite (TBN) as the oxidant without the use of solvent. The possible reaction mechanism is discussed. This protocol provides an expeditious route to the useful 1,2-diketones.     

Zinc-mediated chain extension reaction of 1,3-diketones to 1,4-diketones and diastereoselective synthesis of trans-1,2-disubstituted cyclopropanols

[reaction: see text] A variety of 1,3-diketones can be efficiently converted into the corresponding 1,4-diketones and trans-1,2-disubstituted cyclopropanols by using organozinc species in one-pot reactions. It was found that 2.3 equiv of CF3CO2ZnCH2I was effective to give the corresponding chain-extended products in 44-85% yields, while a mixture of organozinc species formed from 4.0 equiv of Et2Zn, 2.0 equiv of CF3CO2H, and 4.0 equiv of CH2I2 resulted in the formation of trans-1,2-disubstituted cyclopropanols with quite good yields and diastereoselectivity.     

Reaction of benzofurazan oxide with unsymmetrical 1,3-diketones; steric and polar effects

The reaction of benzofurazan oxide 1 with unsymmetrical 1,3-diketones 6a–6w gives isomeric quinoxaline-1,4-dioxides 7 and/or 8. The regiospecificity of ring closure to 7 or 8 is influenced by steric and polar factors in the 1,3-diketone. Mechanistic implications of these findings are presented.     

Copper-catalyzed methylation of 1,3-diketones with tert-butyl peroxybenzoate

Copper-catalyzed radical methylation of 1,3-diketones with tert-butyl peroxybenzoate in air is described, providing a general pathway to α-methyl 1,3-diketones in moderate to good yields. This protocol has been scaled up to 50 g, and one of the synthesized products can be used in the synthesis of medicine, Rosuvastatin.     

Template reactions of fluorine-containing 1,3-diketones with ethylenediamine

Depending on the nature of the dicarbonyl fragment, the reaction of fluorinated copper(II) bis(1,3-diketonates) with ethylenediamine and its monoprotonated salts under mild conditions gives N,N-ethylenebis(aminovinyl ketones) and/or 1,4-diazepines. In excess ethylenediamine, copper(II) and nickel(II) N,N-ethylenebis(aminovinyl ketonates) undergo cyclization to 1,4-diazepines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2088–2092, September, 1991.     

Reactions of substituted 7-aminoindoles with 1,3-diketones

The condensation of 2,3-dimethyl and 1,2,3-trimethyl-7-aminoindoles with-dicarbonyl compounds leads to enaminoketones, which undergo cyclization by the action of trifluoroacetic acid giving substituted pyrrolo[3,2-h]quinolines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 58–62, January, 1995.     

The reaction of oxindoles with β-diketones

With acetylacetone in the presence of hydrogen chloride, oxindole and 1-acetyloxindole form mixtures of approximately equal amounts of 3-isopropylideneoxindole, 2,4-dimethyl-1-oxoniacarbazole chloride, and the hydrochloride of methyl o-aminophenylacetate. In the case of other 1- and 5-substituted oxindoles, the 3-isopropylidene derivatives have been isolated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1271–1272, September, 1973.     

Synthesis of fluorine-containing methoxy-1,3-diketones

A method is proposed for the synthesis of fluorine-containing methoxy-1,3-diketones by hydrolysis of N-phenylaminoalkenyl ketones, produced by the reaction of aniline and the respective methoxyalkynyl ketone in dioxane. With methanol an imine is also formed, and methyl trifluoroacetate is eliminated.Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1390–1392, June, 1992.     

Synthesis of 1,3-diaryl-4,7-phenanthrolines

A number of new 1,3-diaryl-4,7-phenanthrolines were synthesized by heterocyclization of arylidene-6-quinolylamines with acetophenones in the presence of an acidic catalyst. Intermediate amino ketones and side products, viz., N-(R¹-benzyl)-6-quinolylamines and ,-unsaturated ketones, were isolated. The IR, UV, PMR, and mass spectra of the synthesized compounds are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1398–1401, October, 1985.     

Synthesis of 1,3-diaryl-2,2-dichloroethyleneimines

1,3-Diaryl-2-dichloroethyleneimines were synthesized by the reaction of aromatic Schiff bases with chloroform in the presence of potassium tert-butoxide. Several properties of these compounds were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 180–181, February, 1972.     

Electronic effects in the reaction of diphenylcarbonyl oxide with aldehydes

The reactivity of 14 aldehydes with diphenylcarbonyl oxide Ph₂COO was characterized by thek ₃₃/k ₃₁ ratio. The values ofk ₃₃/k ₃₁ vary from 1.3·10⁻² (C₆F₅CHO) to 1.0 (p-Me₂N-PhCHO), 70 °C, acetonitrile as the solvent. A charge transfer complex (CTC) was suggested to be primarily formed during the reaction. The electronic effects of substituents in the reaction were analyzed using the published data. Carbonyl oxide reacts with aldehydes as a nucleophile (at the carbon atom of the −CHO fragment to form 1,2,4-trioxolane) and also as an electrophile (at the aromatic ring with the intermediate formation of CTC). The latter is transformed into either 1,2,4-trioxolane or the products of oxidation of the phenyl ring. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1090–1096, June, 1999.     

The orbital sequence in cyclic 1,3-diketones

The He(I) photoelectron (PE) spectra of the cyclic 1,3-diketones 1–5 have been recorded. Based on a comparison between experimental and calculated (MINDO/3) results it is shown, that in all cases the n_(A) orbital is on top of the n₊(S) orbital. This sequence is confirmed by the comparison between the PE spectra of 1–5 with those of the corresponding vic.triketones 6–10.