Bromination of 5-Substituted 3H-Furan-2-ones and 3H-Pyrrol-2-ones

The bromination of 5-alkyl(aryl)-3H-furan-2-ones and 5-alkyl(aryl)-3H-pyrrol-2-ones and also their derivatives takes place at the ethylene bond with the formation of 4-monobromo derivatives. N-Phenyl-3H-pyrrol-2-ones are brominated simultaneously at the ethylene bond of the heterocycle and at the phenyl substituent at the nitrogen atom.     

A novel route to substituted 3-methylidenechroman-2-ones and 3-methylchromen-2-ones

3-Methylidenechroman-2-ones, or their rearrangement products 3-methylchromen-2-ones, were efficiently synthesized by Michael addition of various nucleophiles to 3-diethoxyphosphorylchromen-2-ones followed by Horner-Wadsworth-Emmons reaction of the adducts with formaldehyde. Relative configuration and conformation of the intermediate adducts were studied using NMR spectroscopy and semiempirical PM3 calculations.     

Michael condensation of 3-arylidene-3H-pyrrol-2-ones and 3-arylidene-3H-furan-2-ones with cyclohexanone

The Michael condensation in the series of 5-aryl-3-arylidene-3H-pyrrol-2-ones and 5-aryl-3-arylidene-3H-furan-2-ones, containing an activated C=C bond, with cyclohexanone was investigated. It was shown that the condensation products were 1,5-dicarbonyl compounds containing a heterocyclic fragment. The enolization of one of the oxo groups, leading to the formation of hydroxypyrrole or hydroxyfuran structures, was demonstrated by the spectral data. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 823–827, June, 2007.     

1-Organyl-2-azasilatran-3-ones

New 1-organyl-2-azasilatran-3-ones have been synthesized via the reaction of trifunctional silanes RSiX₃ (R = Et, Pr, Ph, CH₂=CH, or ClCH₂; X = Cl or Me₂N) with N,N-bis(2-hydroxyethyl)glycinamides (HOCH₂CH₂)₂NCH₂C(O)NHR (R = H or Me) and their N′,O-trimethylsilyl derivatives. The obtained products can be hydrolyzed to give the corresponding organylsilanetriols. Lithiation of 1-methyl- and 1-phenyl-2-azasilatran-3-ones with n-butyllithium or their reduction with lithium aluminum hydride leads to the products of splitting of the atrane backbone RSiBu₃ and RSiH₃ (R = Me or Ph), respectively.     

Parallel synthesis of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones

On the basis of the enaminone methodology, libraries of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones were synthesized by the solid-phase and by the solution-phase parallel synthesis. The solution-phase approach turned out to be advantageous over the solid-phase approach. The solution-phase synthesis afforded, in most cases, analytically pure products in high yields, whereas the solid-phase approach gave products in poor yields and in low purity.     

Regioselective alkylation of 2-alkyl-5,6,7,8-tetrahydro-3h-cycloheptimidazol-4-ones and 2-alkyl-3h-cycloheptimidazol-4-ones

Regioselective alkylation of 2-alkyl-5,6,7,8-tetrahydro-3H-cycloheptimidazol-4-one (1) and 2-alkyl-3H-cycloheptimidazol-4-one (2) was investigated. 3-[2'-(1-tert-Butyl-1H-tetrazol-5-yl)biphenyl-4-ylmethyl]-2-propyl-5,6,7,8-tetrahydro-1H-cycloheptimidazol-4-one (6) was preferentially obtained under the conditions by using NaH in DMF or THF. On the other hand, 3-[2'-(1-tert-butyl-1H-tetrazol-5-yl)biphenyl-4-ylmethyl]-2-propyl-5,6,7,8-tetrahydro-3H-cycloheptimidazol-4-one (5), the synthetic intermediate compound of Pratosartan, was obtained selectively in the presence of n-Bu(4)NBr in toluene by using aqueous sodium hydroxide as a base. In this reaction, it was found that the concentration of the alkaline solution influences its regioselectivity. This selectivity was observed even for aldehyde and ester derivatives.     

A Simple Strategy for the Preparation of 6-Substituted 3H-Benzoxazol-2-ones and 3H-Benzothiazol-2-ones

The double metallation of 6-bromo-3H-benzothiazol-2-one and 6-bromo-3H-benzoxazol-2-one with methyl magnesium bromide and alkyllithium bases is described. Alkylation with a variety of electrophiles occurs at the 6-position of the heterocycles in good yields.      

Synthesis of 2-substituted isothiazolopyridin-3-ones

The synthesis of some 2-substituted derivatives 1–4 of all four isomeric isothiazolopyridin-3-ones is described. Several novel 1,2-dithiolopyridin-3-ones and 3-thiones were prepared as intermediates.     

Cross metathesis with strained exocyclic enones: synthesis of 3-alkylideneoxetan-2-ones from 3-methyleneoxetan-2-ones

[reaction: see text] 3-Alkylideneoxetan-2-ones have been prepared in good to excellent yields with high Z-selectivity by olefin cross metathesis with 3-methyleneoxetan-2-ones in the presence of second generation metathesis catalysts 1 or 2.     

Convenient synthesis of 3-aminomethylenedihydrofuran-2-ones

A simple and convenient synthesis of a series of 3-aminomethylenedihydrofuran-2-ones from the reaction of 3-trichloroacetyl-4,5-dihydrofuran with amines, is presented.     

Synthesis of 3-benzoyl- and 3-trichloroacetylimidazolidin-2-ones

Conclusions The reaction of benzoyl and trichloroacetyl isocyanates with ethylenimine was studied and the structure of the obtained adducts was established.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 447–448, February, 1970.     

4-Sulfenyl-2-carbamoyl-4-isoxazolin-3-ones: biological isostere to 4-chloro-2-carbamoyl-4-isoxazolin-3-ones

4-Sulfenyl-2-carbamoyl-4-isoxazolin-3-ones (4) were designed on the basis of biological isosterism and prepared in four steps. Some of these compounds showed sufficient pre-emergent herbicidal activities against various kinds of weeds. Among the synthesized compounds, 2-(N-(4-chlorophenyl)-N-isopropylcarbamoyl)-4-ethylthio-5-methyl-4 -isoxazolin-3-one (4cd) exhibited the most promising activity.     

Synthesis of 5-methoxylated 3-pyrrolin-2-ones via the rearrangement of chlorinated pyrrolidin-2-ones

The reaction of N-substituted 4-methyl-2-pyrrolidinones or 4-diethoxyphosphoryl analogues, carrying at least two chlorine atoms between the C(3) and C(6) carbons, with alkaline methoxide in methanol afforded the corresponding 5-methoxylated 3-pyrrolin-2-ones, useful adducts for the preparation of agrochemicals or medicinal compounds.     

Formylation of 5-alkyl-3H-furan-2-ones

3-Formyl derivatives of 3H-furanones and 2-chlorofurans are formed in the reaction of 5-alkyl-3H-furan-2-ones with POCl₃ and DMF. The conditions for the purposeful synthesis of these compounds were found. The transformations of the formyl group in reactions with dinitrophenylhydrazine and aniline were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 456–458, April, 1993.     

Photoisomerization of 2H,6H-Thiin-3-ones to 2-(Alk-1-enyl)thietan-3-ones

Reaction of 3-bromo-3-methylbutan-2-one ( 1 ) with mercapto-esters 2 affords 5-oxo-3-thiahexanoates 3 which cyclize to thiane-3,5-diones 4 . Conversion of these dicarbonyl compounds to their ethyl enol ethers 5–7 followed by reduction with LiAlH₄ gives 2H,6H-thiin-3-ones 8–10 . On irradiation (350 nm) in either MeCN, benzene, or i-PrOH, these newly synthesized heterocycles isomerize efficiently to 2-(alk-l-enyl)thietan-3-ones 11–13 . The rearrangement seems to proceed from an excited singlet state, as it is not quenched by naphthalene, and also occurs with the same efficiency in the presence of added alkene. A (9-S-3) sulfuranyl-alkyl biradical formed by bonding of C(α) of the enone C?C bond on sulfur is discussed as possible intermediate.     

Reaction of 3-arylhydrazono-3H-furan-2-ones with o-phenylenediamine

Depending on the conditions, 3-arylhydrazono-3H-furan-2-ones reacted with o-phenylenediamine along two pathways with formation of 2-hydrazonotetrahydrobenzopyrrolo[1,2-a]imidazol-1-ones and 2-(1-aryl-1H-pyrazol-3-yl)benzimidazoles.     

Condensation of arylideneisopropylidenemalonates with 3-carboxyphenylaminocyclohexen-2-ones

Reaction of arylideneisopropylidenemalonates with 3-carboxyphenylaminocyclohexen-2-ones leads to N-carboxyphenyl-4-aryloctahydroquinoline-2,5-diones with elimination of acetone and carbon dioxide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 947–949, July, 1990.