Synthesis and condensation reactions of the boron difluoride complex with 3-acetyl-4-hydroxy-1-methyl-2-quinolone

A reaction of 3-acetyl-4-hydroxy-1-methyl-2-quinolone with boron trifluoride etherate gave its boron difluoride complex. Condensation of this complex with various carbonyl compounds afforded new 2-quinolone derivatives (polymethine and styryl dyes) that intensely absorb in the visible region of the spectrum and show effective fluorescence. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1701–1706, August, 2008.     

Synthesis of 4-hydroxy-2-methylisocarbostyril-3-carboxanilides

A procedure for preparing the title compounds is reported. These compounds represent the first 2-substituted-4-hydroxyisocarbostyrils, a structural type which could not be obtained by N-alkylation of the previously known 2H-4-hydroxyisocarbostyril. Although 3-carboxanilides in this series could not be made by aminolysis of the corresponding 3-ester, they were successfully prepared from 4-hydroxy-2-methylisocarbostyril using aryl isocyanates and sodium hydride in hexamethylphosphoramide as solvent. Evidence is presented for an enolic (“4-hydroxy”) form of the title compounds and preference for O-alkylation was observed. Contrary to previous reports, data was obtained to support the enolic structure of the previously known 4-hydroxyisocarbostyril.     

Synthesis of 4-hydroxy- and 3-aryl-4-amino- 2-trifluoromethylpyridines

Schemes for synthesizing 3-acyl-4-amino(hydroxy)-2-trifluoromethylpyridines from 3-acyl 4-amino-5,5,5-trifluoro-3-penten-2-ones via their diphenylboron chelate complexes have been suggested.Translated fromlzvestiyn Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2715–2718, November, 1996,     

Synthesis of some 2-alkyl-4-quinolone and 2-alkyl-4-methoxyquinoline alkaloids

Acid-catalyzed condensation of a series of 3-oxoalkanoic acid esters with aniline affords the corresponding 2-alkyl-4-quinolones in good yield. Treatment of these compounds with methyl iodide affords 2-alkyl-4-methoxyquinolines and 2-alkyl-N-methylquinolones. Three of the compounds are naturally-occurring alkaloids which are synthesized here for the first time.     

3-氨基-2-羟基-4-苯基丁酸的合成

3-氨基-2-羟基-4-苯基丁酸的合成;乌苯美司;氨基羟基苯基丁酸;合成     

Synthesis of substituted 3-hydroxy-4-alkoxycarbonyl-2-azetidinones

A short chemical process is described for the synthesis of optically active 3-hydroxy-4-alkoxycarbonyl-2-azetidinones (β-lactams) from L-tartaric acid.     

Synthesis of 4-hydroxy-3-triftuoromethylpyrazoles

Trifluoroacetaldehyde hydrazones are condensed with glyoxals to give 4-hydroxy-3-trifluoromethylpyrazoles, the reaction offering a novel route to 4-hydroxypyrazoles carrying trifluoromethyl group. The 4-hydroxyl group was easily converted to its derivatives by the reaction with various electrophiles.     

Synthesis of N-substituted 3-hydroxy-2-methyl-4-pyridones and -pyridonimines

Carbohydrates with 1,4 glycosidic bonds like maltose, lactose, dextrin or starch react with primary amines as well as amino acids or proteins to give i.e. 3-hydroxy-2-methyl-4-pyridones 5 and 3-hydroxy-2-methyl-4-pyridonimines 7. A generally applicable synthesis of compounds of this type is described. The pyridones 5 and pyridonimines 7 are strongly complexing agents. Molybdenum-derivatives, for instance, are suitable as fairly stable oxidation catalysts.     

Synthesis of 1-Benzoyl-3-aryl-4-hydroxy-4-phenylimidazolidin-2-thiones

l-Benzoyl-3-aryl-4-hydroxy-4-phenylimidazolidin-2-thiones can be synthesized readily from the cyclization of 1-benzoyl-3-arylthioureas with bromine-acetophenone in the presence of excess triethylamiqe.     

Synthesis and stereochemistry of 3-hydroxy-4-alkylthiosulfolanes

4-Hydroxy-2-sulfolene, 3-hydroxy-4-chlorosulfolane, and 3,4-epoxysulfolane react with thiols in alkaline media to give mixtures of cis,trans-3-hydroxy-4-alkylthisulfolanes in a ratio of 23.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1631–1636, December, 1979.Original article submitted September 4, 1978; revision submitted June 1, 1979.     

Synthesis and characterization of 4-hydroxy-3-phenylprolines

4-Hydroxy-3-phenylprolines were synthesized via 1-acetyl-2,2-diethoxycarbonyl-2,3-dihydro-3-phenyl-1H-pyrrole. Reversed phase hplc resulted in the isolation of the products which were characterized by ¹H and ¹³C nmr spectroscopy.     

Synthesis and structure of 4-hydroxy-3-pyridylcoumarins

The reaction of substituted 3-cinnamoyl-4-hydroxycoumarins with pyridinium salts of various bromomethyl ketones gives the corresponding 4-hydroxy-3-pyridylcoumarins. The use of microwave radiation decreases the time required and improves the yield of this reaction. The products obtained do not display solvatochromic properties or photochemical activity.     

4-芳亚甲基-2-羟基-3-蒎酮类化合物的合成及其紫外吸收特征研究

以(-)-α-蒎烯为原料合成了系列新型4-芳亚甲基-2-羟基-3-蒎酮类化合物.(-)-α-蒎烯经选择性氧化得到(+)-2-羟基-3-蒎酮;在碱催化作用下,(+)-2-羟基-3-蒎酮与苯甲醛、对甲基苯甲醛、对甲氧基苯甲醛、对羟基苯甲醛、对氯苯甲醛、对硝基苯甲醛和糠醛等芳香醛缩合,得到系列光学活性4-芳亚甲基-2-羟基-3-蒎酮类化合物a～g.采用1H NMR,13C NMR,GC-MS和FT-IR等分析手段对合成所得4-芳亚甲基-2-羟基-3-蒎酮类化合物的结构进行了表征,考察了它们的紫外吸收特性及光稳定性.结果表明,化合物a,b,e对UVB具有良好的吸收性能;而化合物c,d,f,g兼具长波紫外线(UVA)和中波紫外线(UVB)的吸收性能.化合物a～g的光稳定性顺序为d>c>e>f>b>a>g.     

Synthesis of 2-carbethoxy-3-methyl-4-hydroxy-6-phenylbenzofuran derivatives

4-Hydroxybenzofuran derivatives were synthesized, and their reactions with bromine and nitric acid were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 879–882, July, 1976.     

3－烷基-4-羟基-2-噻唑烷硫酮-4-羧酸乙酯的一锅煮合成

Ethyl 3-alkyl-4-hydroxy-2-thioxothiazolidine-4-carboxylates were prepared in excellent yields from the reaction of corresponding primary amines with carbon disulfide and ethyl 3-bromo-2-oxopropanoate in the presence of anhydrous potassium phosphate in DMF at room temperature within 1 h. The structures of the highly functionalized products were corroborated spectroscopically （IR, ^1H NMR, ^13C NMR, EI-MS） and by elemental analyses. A plausible mechanism for such type of cyclization was proposed.     

Synthesis and reactions of 3-aroyl derivatives of 4-hydroxy-2-quinolones and 4-hydroxycoumarin

3-Aroyl-4-hydroxy-2-quinolones 4 and 11 can be synthesized starting with 1 or 9 via Fries rearrangement of the corresponding esters 3 and 10 , catalyzed by potassium cyanide and 18-crown-6. A one pot procedure is presented in which the esters do not need to be isolated. Reduction of the aryl ketones 4 and 11 with zinc dust leads to the benzyl derivatives 5 and 12 . Reaction of the aryl ketones 4 and 11 with hydroxylamine and subsequent heating of the crude product leads via thermal Beckmann rearrangement and dehydration to oxazoloquinolones 7 and 14 . 2-Aroyloxypyrido[1,2-a]pyrimidin-4-ones 17 and 20 could not be converted to the corresponding ketones by Fries rearrangement.     

Synthesis and stereochemistry of 3-hydroxy-6-perfluoroalkyl-2, 3-dihydro-4-pyrones

The reaction of a number of aliphatic and alicyclic acetloxiranes with perfluoroalkanoic acid esters was studied. It is shown that substituted 3-hydroxy-6-perfluoroalkyl-2,3-dihydro-4-pyrones are formed. The reverse reaction scheme, including the formation of an intermediate -diketone and cyclization of its enol form to a dihydropyrone, was confirmed in the case of the condensation of 3-methyl-2,3-epoxycyclohexanone with ethyl trifluoroacetate. The stereochemistry of the reaction products, which exist in a half-chair confirmation with a pseudoequatorial hydroxyl group, was examined by means of PMR spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 897–900, July, 1978.     

2,5-二甲基-4-羟基-3(2H)呋喃酮的合成

以乙酰丙酮(1)为原料，经电解氧化偶联，Paal-Knorr闭环，Baeyer-Villiger氧化，水解等步骤，合成了一种重要的杂环香料，2,5-二甲基-4-羟基-3(2H)呋喃酮(6)。     

Synthesis of 4-norpyridoxine (3-hydroxy-5-hydroxymethyl-2-methylpyridine)

3-Hydroxy-5-hydroxymethyl-2-methylpyridine (4-norpyridoxine) has been synthesized by the heterodiene condensation of 4-methyl-5-propoxyoxazole and 5-ethoxy-2,5-dihydrofuran-2-one through the stage of 3-hydroxy-2-methylpyridine-5-carbaldehyde with reduction of the latter by NaBH₄. One of the isomeric adducts has been isolated, and its stereochemistry has been established by PMR spectroscopy.