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.     

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.     

Preparation and covalent hydration of 4H-imidazole derivatives

2,4,4-Trimethyl-5-phenyl-4H-imidazole, 4H-imidazole 3-oxide, and 4H-imidazole 1,3-dioxide were synthesized from 1-hydroxy-2,5,5-trimethyl-4-phenyl-3-imidazoline and 3-imidazoline 3-oxide, The action of hydrogen chloride on these compounds and on 2,4,4-trimethyl-5-phenyl-4H-imidazole 1-oxide gives products of the addition of water or alcohol — derivatives of 4-hydroxy-2-imidazolinium chlorides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1246–1251, September, 1972.     

Rhodiolosides A-E, monoterpene glycosides from Rhodiola rosea

Five new monoterpene glycosides, rhodiolosides A-E (1-5), were isolated from the roots of Rhodiola rosea (Crassulaceae). Their structures were elucidated as (2E,6E,4R)-4,8-dihydroxy-3,7-dimethyl-2,6-octadienyl beta-D-glucopyranoside (1), (2E,4R)-4-hydroxy-3,7-dimethyl-2,6-octadienyl alpha-D-glucopyranosyl(1-->6)-beta-D-glucopyranoside (2), (2E,4R)-4-hydroxy-3,7-dimethyl-2,6-octadienyl beta-D-glucopyranosyl(1-->3)-beta-D-glucopyranoside (3), (2E,4R)-4,7-dihydroxy-3,7-dimethyl-2-octenyl beta-D-glucopyranoside (4), and (2E)-7-hydroxy-3,7-dimethyl-2-octenyl alpha-L-arabinopyranosyl(1-->6)-beta-D-glucopyranoside (5), on the basis of various spectroscopic analyses and chemical degradation.     

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.     

Synthesis,stereochemistry, and isomeric transformations of cis- and trans-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines

The corresponding trans- and cis-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines were obtained from complexes of cis- and trans-1-methyl-2-aryl-3-aroylaziridines with BF₃ by heating with acetonitrile. The reaction proceeds with inversion of the configuration of the starting 3-aroylaziridines. In the presence of bases the complexes of cis-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines readily undergo isomerization to the corresponding trans analogs. The structures of the products were established on the basis of the IR, PMR, and mass spectra and the results of elementary analysis. The configurations of the compounds were determined by means of the Overhauser nuclear effect.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 952–957, July, 1981.     

Synthesis of the natural enantiomers of ascochlorin,ascofuranone and ascofuranol

Three fungal metabolites with a common structural feature as prenylated phenols were synthesized in their naturally occurring and optically active forms: ascochlorin [(2'$\text{E}$,4'$\text{E}$,1'$\text{R}$,2'$\text{R}$,6'$\text{R}$)-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[5'-(1',2',6'-trimethyl-3'-oxo-cyclohexyl)-3'-methyl-2', 4'-pentadienyl] benzaldehyde], ascofuranone [(2'$\text{E}$,6'$\text{E}$,1'$\text{S}$)-(-)-5-chloro-2, 4-dihydroxy-6-methyl-3-[7'-(3',3'-dimethyl-4'-oxo-2'-oxacyclopentyl)-3',7'-dimethyl -2', 6'-heptadienyl] benzaldehyde] and ascofuranol [(2'$\text{E}$,6'$\text{E}$,1'$\text{S}$,4'$\text{S}$)-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[7'-(3', 3'-dimethyl-4'-hydroxy-2'-oxacyclopentyl)-3', 7'-dimethyl-2',6'-hepta-dienyl]benzaldehyde ]. (+)-Ascofuranone and (+)-ascofuranol were also synthesized. By the present synthesis the absolute configuration of the natural (-)-ascofuranol was established as (1'$\text{S}$,4'$\text{S}$).     

Route to stable nitroxides with alkoxy groups at α- carbon - the derivatives of 2- and 3-imidazolines

Oxidation of 1-hydroxy-5,5-dimethyl-3-imidazoline-3-oxides containing one or two hydrogen atoms in position 2 of the heterocycle with lead dioxide in alcohol leads to stable nitroxides with alkoxy groups at α-carbon, the derivatives of 2- and 3-imidazolines, via the intermediate formation of 4H-imidazol-1,3-dioxides.     

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.     

Benzoid-quinoid tautomerism of Schiff bases and their structural analogs: LV. Crown-containing N-phenylimines derived from ortho-hydroxycarbaldehydes of the coumarin series

Schiff bases were synthesized from 3-hydroxy-6-oxo-6H-benzo[c]chromene-4-carbaldehyde, 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6-carbaldehyde, 6,7-dihydroxy-4-methyl-2-oxo-2H-chromene-8-carbaldehyde, 5,7-dihydroxy-4-methyl-2-oxo-2H-chromene-6,8-dicarbaldehyde, and 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6,8-dicarbaldehyde and (¹⁵N)aniline or aminobenzo-15-crown-5 (2,3,5,6,8,9,11,12-octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-amine), and tautomeric equilibrium between the hydroxy enimino and keto enamino forms of the 4- and 8-iminomethyl derivatives in solution was revealed by 1H NMR and electronic spectroscopy. Addition of alkaline earth cations to their solutions in acetonitrile displaced the tautomeric equilibrium toward the hydroxy enimino structure due to complex formation with the crown ether fragment.     

Acyclic analogs of nucleosides. Synthesis of hydroxyalkyl derivatives of 2-trifluoromethyl- and 2-trifluoromethylthiobenzimidazole

1-(2,3-Dihydroxypropyl)-, 1-(4-hydroxy-2-oxabutyl)-, 1-(3-hydroxymethyl-4-hydroxy-2-oxabutyl)-, 1-(1,5-dihydroxy-3-oxa-2-pentyl)-, 1-(5-hydroxy-3-oxa-2-pentyl)-, and 1-(4,5-dihydroxy-2-oxapentyl)-2-trifluoromethyl- and -2-trifluoromethylthiobenzimidazoles were obtained by condensation of trimethylsilyl derivatives of 2-substituted benzimidazoles with alkylating agents in the presence of SnCl₄, or by direct alkylation of the sodium salts of the heterocycles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 632–636, May, 1988.     

New metallochromic indicators for compleximetric titration of calcium

Seven o,o'-dihydroxyazo dyes were synthesized and tested as metallochromic indicators for calcium: 1-(2-hydroxy-3-sulfo-5-chloro-1-phenylazo)-2-hydroxy-3-naphthoic acid (I), 1-(2-hydroxy-3-sulfo-5-chloro-1-phenylazo)-2-naphthol-3,6-disulfonic acid (II), 1-(2-hydroxy-6-sulfo-1-naphthylazo)-2-naphthol-3,6-disulfonic acid (III), 2,2'-dihydroxy-1, 1'-azonaphthalene-3,3', 6,6'-tetrasulfonic acid (IV), 1-(2-hydroxy-3-carboxy-1-naphthylazo)-2-naphthol-3,6-disulfonic acid (V), 1-(2,3-dihydroxy-1-naphthylazo)-2-naphthol-3, 6-disulfonic acid (VI), 1-(2,3-dihydroxy-6-sulfo-1-naphthylazo)-2-naphthol-3,6-disulfonic acid (VII). The acid dissociation constants and the formation constants of the calcium and magnesium chelates of these dyes were determined. The rate of the decomposition of these dyes and their calcium chelates in alkaline solutions was also examined. From the results of photometric and visual titrations of calcium in the presence of magnesium, indicators III and IV provide the sharpest end-points and the best stability in alkaline solutions.     

Features of the reaction of 3,4-dihydroxy-6-oxo-2,4-alkadienoic acid esters with acetone and <Emphasis Type="Italic">p</Emphasis>-toluidine

Three-component reactions of 3,4-dihydroxy-6-oxo-2,4-alkadienoic acids with acetone and p-toluidine were studied; their specific feature was the formation of the regioisomeric esters of 4-hydroxy-2,2-dimethyl-1-(4-methylphenyl)-5-(2-oxoalkyliden)-2,5-dihydro-1H-pyrrole-3-carboxylic acids and [4-alkanoyl-3-hydroxy-5,5-dimethyl-1-(4-methylphenyl)-1,5-dihydro-2H-pyrrol-2-ylidene]acetic acid. Structure of the synthesized compounds was discussed based on the data of IR and ¹H NMR spectroscopy and X-ray diffraction analysis.     

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.     

Phytoestrogens

Conclusions 1. Eight new representatives of methyl- and methoxycoumestans were obtained.2. For the synthesis of the coumestans, the following previously undescribed coumarins have been synthesize 4,7-dihydroxy-5-methyl-, 4,7-dihydroxy-5-methoxy-, and 4-hydroxy-7-methoxy-5-methylcoumarins.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 3, pp. 355–358, 1970.For part IV, see [4].     

Alkylation of 5-substituted 1-H-tetrazoles by Mannich bases under the action of ultrasound

Alkylation of 5-substituted 1-H-tetrazoles by Mannich bases — N-(3,5-dimethyl-4-hydroxybenzyl)piperidine and N-(2-hydroxy-3-methoxy-5-formylbenzyl)piperidine — under the action of ultrasound increases the yield of the desired products, reduces the reaction time, and improves the regioselectivity.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1060–1063, August, 1993.     

Three new podocarpane-type diterpenoids from callus of Securinega suffruticosa

Three new podocarpane-type diterpenoids, 3beta,12-dihydroxy-13-methyl-6,8,11,13-podocarpatetraen (1), 3beta,12-dihydroxy-13-methyl-5,8,11,13-podocarpatetraen-7-one (2), and 1-(7-hydroxy-2,6-dimethyl-1-naphthyl)-4-methyl-3-pentanone (3) (20(10-->5)-abeo-4,5-seco-5(10),6,8,11,13-podocarpapentaen-3-one) were isolated from callus of Securinega suffruticosa. The structures were elucidated by spectroscopic methods. Compounds 1, 2, and 3 showed cytotoxic activity against five human cancer cell lines (A549, BEL 7402, BGC-823, HCT-8, A2780).     

Facile addition of methyl lithium to a 4-vinylpyridine system

The rapid addition of methyl lithium to the 4-vinylpyridine system present in 4-{2,6-dihydroxy-4-(3-methyl-2-octyl)phenyl}-2-methyl-4-(4-pyridyl)but-3-en-2-ol ( 2 ) is reported. The α and β-4-{2,6-dihydroxy-4-(3-methyl-2-octyl)phenyl}-2,3-dimethyl-4-(4-pyridyl)butan-2-ols 4 and 5 formed, are cyclised by heating with 5N hydrochloric acid to trans and cis-3,4-dihydro-5-hydroxy-7-(3-methyl-2-octyl)-4-(4-pyridyl)-2,2,3-trimethyl-2H-1-benzopyran 6 and 7 respectively.     

Synthesis of nitroxyl radicals — Derivatives of 5,5-dimethoxy-3-imidazoline-3-oxide-1-oxyl from 2H-imidazole 1,3-dioxides

2H-Imidazole 1,3-dioxides containing an aldonitrone fragment in the heterocyclic ring are obtained by the oxidation of 5-unsubstituted 1-hydroxy-3-imidazoline 3-oxides. Their further oxidation by lead dioxide in methanol leads to the formation of stable nitroxyl radicals — 5,5-dimethoxy-3-imidazoline-3-oxide-1-oxyls.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2122–2126, September, 1991.