Isolation and properties of the products of the covalent hydration of 4H-imidazoles

The neutralization of 5-hydroxy-4,4-dimethyl-2-imidazolinium chlorides yields in the free state the products of the covalent hydration of the corresponding 4H-imidazoles — 5-hydroxy-4, 4-dimethyl-2-imidazolines. On being heated, the compounds obtained undergo various transformations, depending on the presence and position of oxygen-containing functions: 5-hydroxy-2-imidazoline gives 2-acetylamino-2-methyl-1-phenylpropan-1-ol; 3,5-dihydroxy-2-imidazoline dehydrates to 4H-imidazole 3-oxide; and 1,5-dihydroxy-2-imidazolines are converted into 2,3-dihydro-4H-1,2,5-oxadiazines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1087–1092, August, 1973.     

NMR spectra of cyclic nitrones. 4. Synthesis and 13C NMR spectra of 4H-imidazole N-oxides and N,N-dioxides

4H-Imidazole 1,3-dioxides and 4H-imidazole 3-oxides were obtained by oxidation of 1-hydroxy-3-imidazoline 3-oxides and 1-hydroxy-3-imidazolines with lead and manganese dioxides or the stable nitroxyl radical, while 4H-imidazole 1-oxides were obtained by thermal decomposition of 1-acetoxy-3-imidazoline 3-oxides. Facile oxidation of the ethyl group in 5-ethyl-4H-imidazole 1,3-dioxide and the formation of 5-acetyl-4H-imidazole 1,3-dioxide and 5-acetyl-4H-imidazole 3-oxide were observed. It is shown that a strictly determined region of chemical shifts of the C(₂), C(₅), and C(₄) atoms is characteristic for each group of 4H-imidazole N-oxides in the ¹³C NMR spectra; this makes it possible to clearly establish the position of the N-oxide oxygen atom.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1640–1648, December, 1988.     

Reduction of 4H-imidazole N-oxides with sodium borohydride

The reduction of derivatives of 4H-imidazole N-oxides with sodium borohydride leads, depending on the presence and position of an N-oxide group, to 1-hydroxyimidazoline or imidazolidine derivatives. Under the same conditions 4H-imidazole N,N-dioxides form 1,3-dihydroxyimidazolidines. The reduction of 1-hydroxy-2,4,5,5-tetramethyl-3-imidazoline 3-oxide leads to N-(3-oximino-2-methyl-2-butyl) ethylhydroxylamine. It was observed by UV spectroscopy that 1-hydroxy-2-imidazolines exist in a tautomeric equilibrium with 2-imidazoline 3-oxides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1557–1561, November, 1976.     

Reaction of 1,2-hydroxylaminooximes with 1,2-diketones. Conversion of 2-acyl-1-hydroxy-3-imidazoline 3-oxides to pyrazine 1,4-dioxides

The reaction of acyclic primary and secondary 1,2-hydroxylaminooximes with aliphatic, alkylaromatic, and alkylheteroaromatic 1,2-diketones, depending on the structure of the starting compounds and the reaction conditions, gives derivatives of pyrazine 1,4-dioxide, 2-acyl-1-hydroxy-3-imidazoline 3-oxide, or mixtures thereof. 2-Acyl-1-hydroxy-3-imidazoline 3-oxides have been converted to pyrazine 1,4-dioxides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 331–338, March, 1986.     

Synthesis and oxidation of 1-hydroxy-3(2)-imidazoline-derived enaminones

Interaction of 1-hydroxy-3-imidazoline and 3-imidazoline 3-oxide derivatives with esters in the presence of LDA gives enaminones, derivatives of imidazolidine. Oxidation of these compounds with MnO₂ leads to4H-imidazoleN-oxides, oxidative dirnerization products, or stable nitroxyl radicals, depending on the structure of the initial compound.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1789–1795, July, 1996.     

Formation of 2-imidazoline derivatives in the reaction of 1,2-hydroxyamino oximes with phenyl- and methylglyoxal

2-Acyl-4-hydroxy-2-imidazoline 3-oxide derivatives were obtained by the reaction of 1,2-hydroxyamino oximes with a hydroxyamino group attached to a tertiary carbon atom with phenyl- and methylglyoxal.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1060–1064, August, 1986.     

Lithiation-methylation of thiasilinane 1-oxides

Lithiation-methylation of 3,3-dimethyl-1λ⁴,3-thiasilinane 1-oxide and 4,4-dimethyl-1λ⁴,4-thiasilinane 1-oxide under the action of butyllithium or lithium diisopropylamide and methyl iodide was studied. In both cases, monomethylation proceeds selectively α to the sulfoxide group to form 2,3,3-trimethyl-1λ⁴,3-thiasilinane 1-oxide and 2,4,4-trimethyl-1λ⁴,4-thiasilinane 1-oxide, respectively. Subsequently, 2,3,3-trimethyl-1λ⁴,3-thiasilinane 1-oxide undergoes monomethylation into the same α position to give 2,2,3,3-tetramethyl-1λ⁴,3-thiasilinane 1-oxide, while 4,4-dimethyl-1λ⁴,4-thiasilinane 1-oxide is dimethylated into the neighboring α’ position to form two stereoisomers of 2,4,4,6-tetramethyl-1λ⁴,4-thiasilinane 1-oxide with axial-equatorial or equatorial-equatorial methyl groups in the 2 and 6 positions.     

Syntheses,structures, and reactions of di- and tetrahydropyrroles

PMR spectroscopy showed that 2,4,4-trimethyl-, 2,4,4-trimethyl-3-carbethoxy-, and 2,4,4-trimethyl-3-acetyl-¹-pyrrolines usually exist in solutions exclusively in the imine form, regardless of the polarity of the solvents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 475–478, April, 1971.     

Use of SPME-GC-MS in the study of time evolution of the constituents of saffron aroma: modifications of the composition during storage

The effect of storage on the composition of saffron aroma is studied. Six samples of saffron from different areas of Italy are analyzed by solid-phase microextraction-gas chromatography-mass spectrometry. Samples 1, 2, and 3 are derived from cultivations of Crocus sativus in the zone of Salerno (Southern Italy) from 2000 to 2002. Samples 4, 5, and 6 are derived from cultivations in Sardinia, Italy (from 1998, 2000, and 2001, respectively). In all samples, 3,5,5-trimethyl-2-cyclohexen-1-one; 3,5,5-trimethyl-2-cyclohexen-1,4-dione; safranal; and 2,4,4-3,5,5-trimethyl-2-cyclohexen-1,4-dione; safranal; and 2,4,4-trimethyl-6-hydroxy-3-carboxaldehyde-2,5-cyclohexadien-1-one are found. 5,5-Dimethyl-2-methylene-1-carboxaldehyde-3-cyclohexene; 3,5,5-trimethyl-1,4-cyclohexandione; and beta-ionone are found with nonanal, dihydro-beta-ionone, and 2,6-di-t-butylphenol. Safranal is the main component in all of the samples. The most important changes are in the presence of alcohols and aldehydes and oxidation products of the major terpenoids components. Furthermore, the presence of safranal--the most important constituent of the flavor--changes during the time, increasing during 3 years, then decreasing after 5 years.     

Facile Synthesis of Novel Pentofuranose Analogs of Phospha Sugar Derivatives

Novel pentofuranose analogs of phospha sugar derivatives were synthesized starting from 1-phenyl-2-phospholene 1-oxide ( 1 ). First, the allylic oxidation of 1-phenyl-2-phospholene 1-oxide ( 1 ) with CrO 3 in Ac 2 O-AcOH or 3-hydroxy-1-phenyl-2-phospholene ( 2 ) with MnO 2 afforded 1-phenyl-4-oxo-2-phospholene 1-oxide ( 3 ). The C-5 alkylation of 3 in the presence of NaH by using benzyl bromide or methyl iodide as electrophiles afforded the target title compounds.     

Influence of nitroxyl radical center on keto-enol equilibrium of β-keto-esters of 3-imidazoline derivatives

Conclusions We used the keto-enol tautomerism of 4-carbomethoxyacetyl-3-imidazolines and 4-carbomethoxyacetyl-3-imidazoline 3-oxides and showed that in contrast to the radicals in the 3-imidazoline series, in the radicals of 3-imidazoline 3-oxide series, the spin effect of the radical center on the position of the tautomeric equilibrium is observed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 653–658, March, 1985.     

Effect of the conditions of the formation of the crystalline phase of 1-hydroxy-5,5-dimethyl-2,4-diphenyl-3-imidazoline-3-oxide on the direction of its reaction with phenyllithium

The course of the heterogeneous reaction of 1-hydroxy-5,5-dimethyl-2,4-diphenyl-3-imidazoline 3-oxide with PhLi is dependent on the conditions of the formation of the crystalline phase of the starting compound. This compound can be isolated mainly in the cyclic or in the chain tautomeric forms.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1175–1176, June, 1995.     

Aminomercuration-demercuration of dimethyl(chloroalkyl)alkenylsilanes as a route to azasilacycloalkanes

3,3-Dimethyl-1-phenyl-1-aza-3-silacyclopentane and 3,3,5-trimethyl-1-phenyl-1-aza-3-silacyclopentane were obtained by the reaction of dimethyl(chloromethyl)vinylsilane and dimethyl(chloromethyl)allylsilane with aniline in THF in the presence of mercury acetate followed by reduction with sodium borohydride. Aminomercuration-demercuration of dimethyl(3-chloropropyl)vinylsilane and dimethyl(3-chloropropyl)allylsilane results in the corresponding 3-chloropropylphenylaminoalkyl derivatives. Dimethyl(3-chloropropyl)(2-phenylaminopropyl)-silane undergoes cyclization under the same reaction conditions giving 2,4,4-trimethyl-1-phenyl-1-aza-4-silacycloheptane in low yield. Competitive nucleophilic substitution of the chloroalkyl group of initial silanes by aniline affords dimethyl(phenylaminoalkyl)alkenylsilanes.     

New derivatives of imidazoline 3-oxide and thiazoline with 2,6-dialkylphenol fragments

(2,6-Dialkyl-4-hydroxyphenyl)-2-butanones and aminooxides were used to obtain the corresponding 3-imidazoline 3-oxides. Nitrosylation of 3-imidazoline 3-oxide containing a phenol substituent proceeds either at the imidazoline ring amino group or at the phenol fragment. Intermolecular cyclization of (2,6-di-tert-butyl-4-hydroxyphenyl)-2-butanone with sulfur and ammonia gave a 3-thiazoline as two diastereomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 62–67, January, 1986.     

Reaction of sterically hindered 1-hydroxy-3-imidazoline 3-oxides with phenyllithium

The reaction of 3-imidazoline 3-oxide derivatives with phenyllithium followed by oxidation affords nitroxyl radicals of the 2-imidazoline or 2-imidazoline 3-oxide series depending on the nature of the substituent in position 2 of the heterocycle.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 292–294, February, 1994.     

Synthesis of a C(9)—C(13) fragment of acutiphycin from levoglucosan

Alkylation of (1R,2R,5R)-2-benzenesulfonyl-6,8-dioxa-bicyclo[3.2.1]octan-3-one, which is accessible from levoglucosan, afforded (1R,2R,5R)-2-benzenesylfonyl-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-one. This was further converted into (1S,2R,3S,5R)-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-ol representing the C9—C13 fragment of acutiphycin molecule.     

Preparation and alkaline cleavage of 4H-imidazole N-oxides

Heating 1-acyloxy-5,5-dimethyl-3-imidazoline 3-oxides in vacuo gives derivatives of 4H-imidazole 1-oxides. The reaction of the latter with alkalis is accompanied by ring opening and the formation of oximes of-acylamino ketones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1241–1245, September, 1972.     

3,6,6-trimethyl-4-oxo-1-(2-pyridyl)-4,5,6,7-tetrahydroindazole in Schmidt reaction and Beckmann rearrangement conditions for the 4-hydroxyimino derivative

Treatment of 3,6,6-trimethyl-4-oxo-1-(2-pyridyl)-4,5,6,7-tetrahydroindazole with sodium azide in acids gives 3,7,7-trimethyl-5-oxo-1-(2-pyridyl)-5,6,7,8-tetrahydro(4H)pyrazolo[4,3-b]azepine. Heating 1-(2-pyridyl)-3,6,6-trimethyl- and 1-phenyl-6,6-dimethyl-4-hydroxyimino-4,5,6,7-tetrahydroindazoles in polyphosphoric acid gives 1-phenyl-5,6-dimethyl- and 1-(2-pyridyl)-3,5,6-trimethyl-4-aminoindazole respectively: The reactions of the latter with 4-dimethylaminobenzaldehyde gave the 4-(4-dimethylaminobenzalamino) derivative and with 2-formyldimedone the 4-(4,4-dimethyl-2,6-dioxocyclohexylidenemethylamino) derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 830–834, June, 2000.