Six new 2-(2-phenylethyl)chromones from Agarwood

Six new chromones, 6-methoxy-2-[2-(3-methoxy-4-hydroxyphenyl)ethyllchromone (2), 6,8-dihydroxy-2-(2-phenylethyl)chromone (3), 6-hydroxy-2-[2-(4-hydroxyphenyl)ethyl]chromone (4), 6-hydroxy-2-[2-(2-hydroxyphenyl)ethyl]chromone (5), 7-hydroxy-2-(2-phenylethyl)chromone (6), and 6-hydroxy-7-methoxy-2-(2-phenylethyl)chromone (7) were isolated from the ether extract of agarwood in addition to a known compound, 2-(2-phenylethyl)chromone or flidersiachromone (1). Their structures were determined by spectroscopic methods including UV, IR, and NMR spectral data and comparisons with the calculated values using the hydroxyl and methoxyl substituent increments of the chromone ring.     

Four new 2-(2-phenylethyl)chromone derivatives from withered wood of Aquilaria sinensis

Four new chromone derivatives, 5-hydroxy-6-methoxy-2-(2-phenylethyl)chromone (1), 6-hydroxy-2-(2-hydroxy-2-phenylethyl)chromone (2), 8-chloro-2-(2-phenylethyl)-5,6,7-trihydroxy-5,6,7,8-tetrahydrochromone (3), 6,7-dihydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydrochromone (4) were isolated from the MeOH extract of withered wood of Aquilaria sinensis, together with seven known constituents of agarwood.     

Reaction of natural isoflavonoids and their analogs with hydroxylamine

Recyclization of the chromone ring in several natural isoflavonoids and their analogs by reaction with hydroxylamine was studied. It has been found that the most suitable base for carrying out the reaction is N-methylmorpholine. Several derivatives of 4-aryl-5-(2-hydroxyphenyl)isoxazole were synthesized. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 332–336, July–August, 2007.     

Three 2-(2-phenylethyl) chromones and two terpenes from agarwood

A new Chromone, 7,8-dimethoxy-2-[2-(3'-acetoxyphenyl)ethyl]chromone (1) was isolated from an acetone extract of the Cambodian agarwood along with two known chromones, 6-methoxy-2-(2-phenylethyl)chromone (2) and 6,7-dimethoxy-2-(2-phenylethyl)chromone (3). In addition, an abietane ester (4) and the sesquiterpene dehydrofukinone (5) were isolated from the agarwood oil of the same origin. Structural elucidation of all isolated compounds was made based on IR, 1H and 13C NMR spectroscopic data.     

Studies on heterocyclic compounds. VII. Syntheses of novel furo[2, 3-b]chromones

Furo[2, 3-b]chromone ( 1a ) was conveniently prepared by the PPE-promoted cyclization of 5-(2′-carboxy-phenoxy)furan-2-carboxylic acid ( 8 ) which was made from methyl salicylate and ethyl 5-nitrofuran-2-carboxyl-ate. Furo[2, 3-b]chromon-2-acrylic acid ( 13 ) was obtained by a similar cyclization. Direct acylation of 1a afforded 2-acetylfuro[2, 3-b]chromone ( 10 ). Several derivatives of furo[2, 3-b]chromone were found to display activity in the rat passive cutaneous anaphylaxis (PGA) test for antiallergic activity.     

Researches on pyranes,their analogs,and related compounds

Condensation of 2, 4-diacetylphenol with diethyl oxalate serves as a basis for preparing 2-carbethoxy- and 2-carboxy-6-acetylchromones (I, II), 2-carbethoxy-6-ethoxyoxalyacetylchromone (V), and 2-carboxy-6-hydroxyoxalylacetylchromone (VI). The Mannich reaction is used to synthesize 6-(ω-dialkylaminopropionyl)-2-carboxychromones (VII, VIII) from compound I. Reaction of chromone-2-carbonyl chloride with enamines prepared from cyclohexanone and tetrahydrothiopyrone-4- gives syntheses of 2-(chromonoyl-2)cyclohexanone (III) and 3-(chromonoyl-2)tetrahydrothiopyrone-4 (IV). Hydrazine hydrate and compound III give the pyrazole derivative IX, while hydrazine hydrate and compound IV give pyrazole derivative X along with pyrazolylpyrazole derivative XI, which results from a second molecule of hydrazine hydrate opening the chromone ring. For Part XX see [11].     

New sesquiterpenes from Ferula ferulaeoides (Steud.) Korovin. VI. Isolation and identification of three new dihydrofuro[2,3-b]chromones

Three novel 2-prenyl-dihydrofurochromone-type sesquiterpenoid derivatives, 2,3-dihydro-7-hydroxy-2S*,3R*-dimethyl-2-[4,8-dimethyl-3(E),7-nonadienyl]-furo[2,3-b]chromone, 2,3-dihydro-7-hydroxy-2S*,3R*-dimethyl-2-[4-methyl-5-(4-methyl-2-furyl)-3(E),7-pentenyl]-furo[2,3-b]chromone, and 2,3-dihydro-7-hydroxy-2R*,3R*-dimethyl-2-[4-methyl-5-(4-methyl-2-furyl)-3(E),7-pentenyl]-furo[2,3-b]chromone, were isolated from the roots of Ferula ferulaeoides. The structures were established by comprehensive spectral analysis. The biosynthetic pathway leading to these 2-prenyl-dihydrofurochromone-type sesquiterpenoids is proposed based on their structures.     

Synthesis of Some New 1,3,2-Oxazaphosphinine, 1,3,2-Diazaphosphinine,Acyclic, and/or Cyclic α-Aminophosphonate Derivatives Containing the Chromone Moiety

The synthesis of some new 1,3,2-oxazaphosphinine 18, 1,3,2-diazaphosphinine 19, acyclic, and cyclic α-aminophosphonate derivatives 3–17 containing the chromone moiety have been achieved via reaction of 3-(phenyliminomethyl)chromone (1), 3-(phenylaminomethylene)-2-hydroxychromanone (4), and/or 3-(phenylamino-methylene)-2-(phenylamino)chromanone (5) with diethyl phosphite, tris(2-chloroethyl)phosphite, and phenylphosphonic dichloride. Structures of the products were verified on the basis of their elemental analyses, IR, ¹H, and ³¹P NMR spectral data.     

New 2-(2-phenylethyl)chromone derivatives from agarwood and their inhibitory effects on tumor cells

Abstract

Two new chromone derivatives, 7-hydroxy-2-[2-(3'-methoxy-4'-hydroxyphenyl)-ethyl]chromone (1), and 6,7-dimethoxy-2-[2-(3'-hydroxyphenyl)-ethyl]chromone (2) were isolated from the EtOH extract of agarwood of Aquilaria sinensis, together with eleven known analogues. Their structures were established by detailed HR-ESIMS, 1D and 2D NMR spectroscopic analysis, as well as comparison with the literature data. Selected the isolates (1, 2, 4–8, 10, 11) were tested for their antitumor activities against SMMC-7721, MGC-803 and OV-90 cell lines using the MTT method with cisplatin and paclitaxel as the positive control. All the tested compounds showed weak cytotoxic activities with IC₅₀ values ranged from 18.82 to 37.95 µg/ml.     

A new chromone from seeds of <Emphasis Type="Italic">Cydonia oblonga</Emphasis>

The new chromone 5,7-dihydroxy-2-n-pentacosanylchromen-4-one (1) in addition to the three known compounds ursolic acid (2), tormentic acid (3), and β-daucosterol (4) were isolated from seeds of Cydonia oblonga. Their structures were determined based on their 1D and 2D NMR and HR-ESI-MS spectral data.     

The Reaction of 3-Formylchromone with ortho-Substituted Anilines. Preparation of a Tetraaza [14]annulene

The reactions of 3-formylchromone ( 1 ) with 1, 2-phenylenediamine, 2-amino-diphenylamine and 2-aminophenol were reinvestigated and shown to yield 1, 8-dihydro-6, 13-di (2-hydroxybenzoyl)-dibenzo [b, i]-l, 4, 8, 11-tetraazacyclotetradeca- 4, 6, 11,13-tetraene ( 7 ), 3-[2-(1-phenyl)benzimidazolyl]chromone ( 10b ) and 3-(2-hydroxyphenyl)iminomethylchromone ( 4 ), respectively at variance with earlier reports. Compound 4 reacts with ethanol to give 2-ethoxy-3-[(2-hydroxyphenyl)-aminomethylidene]chroman-4-one ( 5b ). Dehydrogenation of 7 produces 3-(2-benz-imidazolyl)chromone ( 10a ), also at variance with earlier reports. The structures have been elucidated with the aid of NMR. and mass spectra. The reaction mechanism is discussed.     

Mushroom tyrosinase inhibition activity of some chromones

Currently, aloesin is used in the cosmetic industry as a whitening agent because it inhibits tyrosinase activity. Aloesin is a C-glycosylated chromone compound isolated from aloe, and it is difficult to synthesize because of C-glycosyl moiety in the molecule. The purpose of this study is to search for a new chromone compound which is easy to synthesize and which posesses stronger tyrosinase inhibitory activity than aloesin. Fourteen chromone derivatives were synthesized and screened for their mushroom-tyrosinase inhibitory activity. 5-Methyl-7-methoxy-2-(2'-benzyl-3'-oxobutyl)chromone (15) showed the strongest activity among tested compounds. Its activity was not only stronger than aloesin, but also stronger than arbutin and kojic acid. The kinetic analysis revealed a competitive inhibition of 15 with tyrosinase for the L-tyrosine binding site.     

2-[6-Alkyl-3-hetaryl-4-oxo-9,10-dihydro-4H,8H-chromeno-[8,7-<Emphasis Type="Italic">e</Emphasis>][1,3]oxazin-9-yl]acetic acids

The interaction has been studied of a series of substituted 3-hetaryl-7-hydroxychromones with amino acids and formaldehyde (reactants ratio 1: 1: 2 respectively). In the case of glycine and Het = 3-isoxazolyl the product of aminomethylation at position 8 of the chromone was obtained, and with other Het (including Het = 4-phenyl-1,2,4-triazol-3-yl) 2-[6-alkyl-3-hetaryl-4-oxo-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]-oxazin-9-yl]acetic acids were formed. With β-alanine and Het = 4-phenyl-1,2,4-triazol-3-yl the corresponding β-substituted propionic acid was synthesized, but proline did not participate in the reaction, leading to bis(6-ethyl-3-hetaryl-7-hydroxychromon-8-yl)methane. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 683–689, May, 2007.     

α-Halogenoketones—XIV: Studies in the chemistry of 2''-hydroxyacrylophenones

The chromone epoxide ring system has been synthesised. Base-catalysed cyclization and dehydrobromination of α-bromo-o-acyl (aroyl) oxyacetopheones or 2-bromo-1, 3-diones yielded 3-substituted chromone epoxides. Acid-catalysed rearrangement of a 2-methylchromone epoxide in an aprotic solvent gave a 2-methylenech-romanonol, while a 3-methoxymethylchromone epoxide fragmented to chromonol under these conditions; in alchols, chromone epoxides gave 2-alkoxychromanonols.     

-Halogenoketones—XIII Chromone epoxides; their synthesis and acid-catalysed rearrangement

The chromone epoxide ring system has been synthesised. Base-catalysed cyclization and dehydrobromination of -bromo-o-acyl (aroyl) oxyacetopheones or 2-bromo-1, 3-diones yielded 3-substituted chromone epoxides. Acid-catalysed rearrangement of a 2-methylchromone epoxide in an aprotic solvent gave a 2-methylenech-romanonol, while a 3-methoxymethylchromone epoxide fragmented to chromonol under these conditions; in alchols, chromone epoxides gave 2-alkoxychromanonols.     

Reactions of 2(3)-ethoxycarbonyl-5,6,7,8-tetrafluorochromones with methylamine

2-Ethoxycarbonyl-5,6,7,8-tetrafluorochromone reacts with methylamine differently, depending on the solvent nature and the amount of the amine: in DMSO and MeCN, the fluorine atom at the C(7) atom is initially replaced and then the C(2) and/or C(9) are attacked, while in ethanol, the reaction involves the C(2) atom with opening of the pyrone ring. The reaction of 3-ethoxycarbonyl-5,6,7,8-tetrafluoro-2-methylchromone with methylamine results, regardless of the solvent, in opening of the chromone ring and the formation of intermediate ethyl 3-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)-2-(1-methylamino)ethylidene-3-oxopropionate, which undergoes intramolecular cyclization to give 5,6,7,8-tetrafluoro-3-(1-methyl-amino)ethylidene-3,4-dihydro-2H-benzopyran-2,4-dione. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2093–2098, September, 2005.     

芦荟色酮的高速逆流色谱分离制备方法研究

芦荟色酮是在芦荟叶中特有的一类具有抗炎和抑制酪氨酸酶等作用的活性物质。以芦荟全叶为原料,经过一系列的预处理手段,从脱色剂活性炭中获得芦荟色酮粗提物,再经过溶剂分配和富集后采用高速逆流色谱（HSCCC）对其中的色酮成分进行分离纯化。研究结果表明,采用氯仿-甲醇-水(体积比为4∶3∶2)混合溶液和二氯甲烷-甲醇-水(体积比为5∶4∶2)混合溶液作为溶剂分离系统,经过两步HSCCC可以分离纯化出色谱纯度在95％以上的芦荟色酮单体。经过紫外检测、快原子轰击质谱及核磁共振等方法的结构分析鉴定,证实分离所得物质为肉桂酰基-C-葡萄糖甙芦荟色酮。     

Protogenkwanin 4′-glucoside,a new type of natural flavonoid with a non aromatic B-ring

From fertile sprouts of $\text{Equisetum arvense}$ L. (Equisetaceae) a flavonoid has been isolated and called protogenkwanin 4′-glucoside (2-(4-β-D-glucosyloxy-1-hydroxy-2,5-cyclohexadienyl)-5-hydroxy-7-methoxy chromone). Its structure has been established on the basis of chemical and spectroscopical evidences.     

Bioactive metabolites from <Emphasis Type="Italic">Penicillium</Emphasis> sp. P-1, a fungal endophyte in <Emphasis Type="Italic">Huperzia serrata</Emphasis>

A chemical study of metabolites of the strain Penicillium sp. P-1, an endophyte from the stems of Huperzia serrata, furnished a new chromone derivative, (2S)-2,3-dihydro-7-hydroxy-6,8-dimethyl-2-[(E)-prop-1-enyl]- chroman-4-one (1), an enantiomer of a known compound, and seven known compounds 2–8. The structure and absolute configuration of 1 were established using spectroscopic methods, including extensive 2D NMR and CD analyses. Cytotoxic activity of compounds 1–3 against HeLa and HepG2 cell lines were evaluated, in which compounds 2 and 3 exhibited marked cytotoxic activity against HeLa cells.     

Chalcone dihalides—II : The similarity of the effects of 2-thienyl and 4-methoxyphenyl substituents in the side chain

2,3-Dibromo-2′-hydroxy-3-(2-thienyl)propiophenones, with base, gave mixtures of the corresponding chromone and coumaranone and were readily converted into their 3-alkoxyl derivatives. Chromones were obtained by pyrolysing the dibromides and coumaranones by treatment of the 3-alkoxyl derivatives with aqueous ethanolic alkali.