Chemistry of the heteroanalogs of isoflavones. 20. Benzimidazole analogs of isoflavones

3-(2-Benzimidazolyl)chromones with electron-donating and electron-withdrawing substituents and also chromones unsubstituted at position 2 were obtained by the reaction of alkyl--(2-benzimidazolyl)-2,4-dihydroxy-5-acetophenones with carboxylic acid anhydrides and chlorides. Reactions with cleavage and with retention of the pyrone ring were carried out.For Communication 19, see [1].Taras Shevchenko Kiev University, Kiev. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1237–1244, September, 1997.     

Chemistry of heteroanalogs of isoflavones. 16. Benzthiazole analogs of isoflavones

The reaction of a-(2-benzthiazolyl)-2, 4-dihydroxy-5-alkylacetophenones with anhydrides and chlorides of carboxylic acids yielded 3-(2-benzthiazolyl)chromones with electron-acceptor and electron-donor substituents, as well as chromones unsubstituted in the 2 -position. Their acylation, alkylation, and aminoacylation reactions and their interaction with electrophilic and nucleophilic reagents were studied.Taras Shevchenko Kiev University, Kiev 252017. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 464–471, April, 1994. Original article submitted March 5, 1994.     

Chemistry of heteroanalogs of isoflavones 14. Isoxazole analogs of isoflavones

Isoxazole analogs of isoflavones have been synthesized by the cyclization of -(3-isoxazolyl)-2-hydroxyacetophenones. Their alkylation, acylation, and electrophilic substitution reactions, and reactions with binucleophiles have been studied. 3-(3-Isoxazolyl)-7-methoxychromones are rearranged selectively into 2-aminochromone derivatives by the action of hydroxylamine as a result of a double recyclization and are recyclized into pyrazole derivatives by hydrazine. Preparations with hypolipidemic, anabolic, hypoglycemic, and antiarrhythmic action are found among the derivatives of 3-(3-isoxazolyl)chromones.For Communication 13, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 29–39, January, 1993.     

Chemistry of heteroanalogs of isoflavones. 8. Reaction of benzofuran analogs of isoflavones and their 4-thioxo derivatives with hydroxylamine and hydrazine

A number of 3-(2-benzofuryl)-6-ethylchromones and their 4-thioxo derivatives were synthesized, and the action of hydroxylamine and hydrazine on them was investigated. Isomeric 3 (5)-(o-hydroxyphenyl) isoxazoles were obtained in the reaction with hydroxylamine. The predominant formation of one or the other isomer depends on the character of the substituents in the 2 and 4 positions of the chromone. The reaction of chromones with hydrazine leads to o-hydroxyphenylpyrazoles. The compounds obtained were characterized by their IR, UV, and PME spectra.See [ 1] for Communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 892–897, July, 1981.     

Chemistry of modified flavonoids. XVIII. Thiazole analogs of isoflavones. Homologous and isomeric series

Homologous and isomeric series of thiazole derivatives of isoflavones were produced on the basis of -(4-methyl-2-thiazolyl)-2-hydroxyacetophenones. A study of -(4-methyl-2-thiazoyl)-2-hydroxyacetophenones by PMR spectroscopy showed that these compounds exist in most nonpolar and low polarity organic solvents exclusively in the ketone form, but in dimethyl sulfoxide solution both the ketone and enol forms are observed in various ratios. A simple and effective preparative method of synthesis of homologs of 3-(2-diazolyl)-chromones was developed, and their alkylation at the phenolic hydroxyl was studied. Data of biological tests of the compounds synthesized are presented.For communication 17, see [1].T. G. Shevchenko Kiev University, Kiev 252601. Translated from Khimiya Geterotsikiicheskikh Soedinenii, No. 4, pp. 505–513, April, 1995. Original article submitted March 19, 1995.     

Chemistry of the heteroanalogs of isoflavones

3-(1-Benzimidazolyl)chromones were obtained by the reaction of -(1-benzimidazolyl)-2,4-dihydroxy-5-ethylacetophenone with trifluoroacetic anhydride and acetic formic anhydride.For Communication 20, see [1].Taras Shevchenko National University. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1377–1379, October 1997.     

Synthetic analogs of natural flavolignans IX. Synthesis of 3-amino-substituted analogs of hydnocarpin

New 3-amino-substituted chromones with 1,3-benzodioxan and 1,4-benzodioxan nuclei in position 2 have been synthesized. The structures of the compounds obtained have been confirmed by their PMR spectra.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 178–181, March–April, 1999.     

Use of lanthanide shift reagents for studying pyridine analogs of isoflavones

The interaction of lanthanide shift reagents (LSR) with pyridine analogs of isoflavone and their derivatives has been studied. It was found that the pyridine nitrogen atom can increase the coordinating ability of electron donor groups in the molecule, in particular the sulfur atom in chromone thiones. It has been shown that LSR interact actively with pyridinium methylsulfate salts containing the 3-chromone substituent. The efficiency of the coordination is influenced by the occurrence of steric hindrance around the chromone carbonyl. The structure of the adducts of these salts with LSR is discussed.Taras Shevchenko University, Kiev 252033, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 342–345, March, 1998.     

Chemistry of heteroanalogs of isoflavones

Condensation of cyanomethyl derivatives of benzimidazole and benzothiazole with resorcinol gave the corresponding 2,4-dihydroxy-α-hetarylacetophenones. The latter were converted to 3-hetarylchromones with methyl, trifluoromethyl, and ethoxycarbonyl groups in the 2 position or to chromones without substituents in this position.     

Chemistry of heteroanalogs of isoflavones. 23. Synthesis of aminoacyl derivatives of 3-phenoxychromone

Reaction of Boc-protected amino acids with 3-phenoxy-2-trifluoromethylchromones gave new, previously unknown aminoacyl derivatives.T. G. Shevchenko Kiev University, Kiev 252033, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 744–748, June, 1999.     

Reactions of 3-(polyfluoroacyl)chromones with hydroxylamine. The first synthesis of 3-cyano-2-(polyfluoroalkyl)chromones

Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine proceeds via nucleophilic 1,4-addition followed by opening of the pyrone ring and subsequent cyclization to 4-(polyfluoroalkyl)-4H-chromeno[3,4-d]isoxazol-4-ols in good yields. On treatment with trifluoroacetic acid, the isoxazole ring of this annulated heterocyclic system opens to give 3-cyano-2-(polyfluoroalkyl)chromones. Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine hydrochloride occurs only at the carbonyl carbon atom connected to the R^F group to give the corresponding oximes in low yields.     

Structural revision in the reactions of 3-cyanochromones with primary aromatic amines. Improved synthesis of 2-amino-3-(aryliminomethyl)chromones

3-Cyanochromones react with primary aromatic amines to give 2-amino-3-(aryliminomethyl)chromones as the sole products or as their mixtures with Z- and E-3-anilino-2-salicyloylacrylonitriles, depending on the reaction conditions. With aliphatic amines, 2-amino-3-(alkyliminomethyl)chromones are obtained in good yields. The reaction of 3-cyanochromone with o-phenylenediamine is reinvestigated and proof for the product structure and a possible reaction pathway are presented.     

Thiazole analogs of chalcone and flavone

New thiazole analogs of chalcones and their epoxides were obtained. Thiazole analogs of flavone and isoflavone were synthesized for the first time on the basis of these compounds. It is shown that o-hydroxyphenylpyrazole derivatives are formed by the action of hydrazine hydrate on 2-(4-thiazolyl)chromones. The PMR spectra of the new substances are presented and discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1202–1208, September, 1981.     

Bromination and Azidation Reactions of 2-Styrylchromones. New Syntheses of 4(5)-Aryl-5(4)-(2-chromonyl)-1,2,3-triazoles

The bromination of 2-styrylchromones, bearing electron neutral substituents, with two molar equivalents of piridinium tribromide gave 2-(2-aryl-1,2-dibromoethyl)chromones and 3-bromo-2-(2-aryl-1,2-dibromoethyl)chromones. The presence of electron-donating substituents on their B ring led to a mixture of compounds due to the higher reactivity of their C(2)=C(3) and C=C double bonds, whereas the strongly electron-withdrawing group hindered the bromination. The dehydrobromination of 2-(2-aryl-1,2-dibromoethyl)chromones with triethylamine gave a diastereomeric mixture of (E)- and (Z)-2-(-bromostyryl)chromones. Some novel 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles have been obtained from the reactions of 2-(2-aryl-1,2-dibromoethyl)chromones, 2-(-bromostyryl)chromones, and 2-styrylchromones with sodium azide. The reactions of 2-styrylchromones with sodium azide are more efficient, general, and constitute a one-pot synthetic method of 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles allowing the preparation of 1,2,3-triazoles bearing either electron-donating or electron-withdrawing substituents in their aryl ring. The structure of all new compounds was established by extensive NMR spectroscopic studies.     

Bromination and Azidation Reactions of 2-Styrylchromones. New Syntheses of 4(5)-Aryl-5(4)-(2-chromonyl)-1,2,3-triazoles

Summary. The bromination of 2-styrylchromones, bearing electron neutral substituents, with two molar equivalents of piridinium tribromide gave 2-(2-aryl-1,2-dibromoethyl)chromones and 3-bromo-2-(2-aryl-1,2-dibromoethyl)chromones. The presence of electron-donating substituents on their B ring led to a mixture of compounds due to the higher reactivity of their C(2)=C(3) and C=C double bonds, whereas the strongly electron-withdrawing group hindered the bromination. The dehydrobromination of 2-(2-aryl-1,2-dibromoethyl)chromones with triethylamine gave a diastereomeric mixture of (E)- and (Z)-2-(-bromostyryl)chromones. Some novel 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles have been obtained from the reactions of 2-(2-aryl-1,2-dibromoethyl)chromones, 2-(-bromostyryl)chromones, and 2-styrylchromones with sodium azide. The reactions of 2-styrylchromones with sodium azide are more efficient, general, and constitute a one-pot synthetic method of 4(5)-aryl-5(4)-(2-chromonyl)-1,2,3-triazoles allowing the preparation of 1,2,3-triazoles bearing either electron-donating or electron-withdrawing substituents in their aryl ring. The structure of all new compounds was established by extensive NMR spectroscopic studies.     

Chemistry of modified flavonoids 17. Imidazole analogs of flavonoids

Summary Imidazole analogs of chalcones were synthesized by the reaction of 1-methyl-2 formyl-5-chloroimidazole with o-hydroxyacetophenones. Isomerization and oxidative cyclization of chalcones yielded imidazole analogs of flavonones and flavones. These compounds were used in the synthesis of pyrazolines, pyrazoles, and isoxazoles.Taras Shevchenko Kiev University, Kiev 252017. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1063-1070, August, 1994.For Communication 16 see [1].     

Reactions of 3-(polyfluoroacyl)chromones with hydroxylamine: synthesis of novel R-containing isoxazole and chromone derivatives

Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine free base proceeds via nucleophilic 1,4-addition followed by opening of the pyrone ring and subsequent cyclization to 4-(polyfluoroalkyl)-4H-chromeno[3,4-d]isoxazol-4-ols in good yields. On treatment with trifluoroacetic acid, the isoxazole ring of this annulated heterocyclic system opens to give 3-cyano-2-(polyfluoroalkyl)chromones, which were successfully hydrolyzed with concentrated H₂SO₄ to afford 3-carbamoyl-2-(polyfluoroalkyl)chromones. On the other hand, oximation of 3-(polyfluoroacyl)chromones with hydroxylamine hydrochloride occurs either at the carbonyl carbon atom connected to the R^F group or at the C-2 atom to give 3-R^FC(NOH)-chromones and 5-R^F-4-salicyloylisoxazole oximes, respectively. The former were easily converted to 3-R^F-4-salicyloylisoxazoles by simple heating in dimethyl sulfoxide.     

Synthetic and modified isoflavonoids XIX. Synthesis of 8-methyl-substituted analogs of pseudobaptigenin

New 8-methyl-substituted chromones with 1,4-benzodioxane and 1,5-benzodioxepane nuclei in position 3 have been synthesized. Their structures have been confirmed by chemical transformations and PMR spectra.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 370–374, May–June, 1997.     

Features of the reaction of heterocyclic analogs of chalcone with lanthanide shift reagents

The PMR spectra of heterocyclic analogs of 2-hydroxychalcone containing thiazole, benzofuran, triazole, imidazole, benzodioxane, or pyridine rings in the presence of lanthanide shift reagents are studied. It is found that the most effective reagent for modifying the spectra of these compounds is Yb(fod)3. The broadening of the spectra of 2-hydroxy chalcones in the presence of lanthanide shift reagents is explained by the dynamic effects of complex formation. An example is given of the determination of the conformation of molecules of 2-hydroxychalcone by the simultaneous use of lanthanide shift reagents and the homonuclear Overhauser effect.Taras Shevchenko Kiev University, Kiev 252017. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 457–463, April, 1994     

Asymmetric synthesis of organoelemental analogs of natural compounds. 7. (2R,3S)-2-amino-3-hydroxy-5-phosphonovaleric acid

The reaction of the Ni(II) complex of the Schiff base of glycine with (S)-2-N-(N¹-benzylprolyl)-o-aminobenzophenone with diethyl-3-bromo-2-hydroxypropyl phosphonate yields the corresponding complex from which (2R, 3S)-2-amino-3-hydroxy-5-phosphonovaleric acid is separated with HCl.See [1] for Communication 6.Institute of Bioorganic Chemistry and Petrochemistry, Ukrainian Academy of Sciences, 252660 Kiev; N. A. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1172–1175, May, 1992.