Studies on triacetic acid lactone-annulated heterocycles: synthesis of 3-aryloxyacetyl-6-methyl-2,3-dihydrothieno[3,2-c]pyran-4-ones by tandem cyclization

The hitherto unreported 3-aryloxyacetyl-6-methyl-2,3-dihydrothieno[3,2-c]pyran-4-ones were synthesized in 62–71% yield by the sulfoxide rearrangement of 4-(4′-aryloxybut-2′-ynylthio)-6-methyl-2-pyrone. The substrates were synthesized by phase-transfer-catalysed alkylation of the hitherto unreported 4-mercapto-6-methylpyran-2-one.     

Efficient synthesis of pyranochromene derivatives via three-component reaction of 4-hydroxy-6-methylpyran-1-one with aromatic aldehydes and cyclic 1,3-diketone catalyzed by ZnO nanoparticles

Russian Journal of General Chemistry - Three-component reaction of 4-hydroxy-6-methylpyran-1-one with aromatic aldehydes and cyclic-1,3-diketone catalyzed by ZnO nanoparticles under solvent-free...     

水介质中吡喃并[3,2-c]吡喃-5-酮衍生物的三组分一锅合成

水介质中在氯化三乙基苄基铵(TEBAC)催化下, 芳醛与丙二腈和4-羟基-6-甲基吡喃-2-酮三组分一锅反应合成了一系列2-氨基-3-氰基-4-芳基-4H,5H-吡喃-5-酮. 该反应具有产率高、污染少、操作简单、环境友好等优点.     

合成3-苯甲酰胺基-6-甲基-2-吡喃酮衍生物的新方法

以马尿酸、原甲酸三乙酯和乙酰乙酸乙酯或乙酰丙酮为原料,合成了两个3-苯甲酰胺基-6-甲基-2-吡喃酮衍生物(总产率66％)和一个新化合物——3-苯甲酰胺基-5-羟乙基-6-甲基-2-吡喃酮(总产率42％),其结构经1H NMR和13C NMR表征.     

Furannes et pyrroles disubstitués en 2,3. XVI synthèse de furo[3,2-c]pyranones-4 et nouvelle voie d'accès aux furo[3,2-c]pyridines

Treatment of 4-hydroxy-6-methylpyran-2-one with chloracetalhyde in basic aqueous medium gave 6-methylfuro[3,2-c]pyran-4-one. This compound reacted with ammonium hydroxide and some primary amines to form the corresponding N-substituted furo[3,2-c]pyrid-4-ones which may also be obtained from 4-hydroxy-α-pyridones. Furo[3,2-c]pyran-4-one was acylated at the 2 position and 4-chloro-6-methylfuro[3,2-c]pyridine easily gave 4-substituted derivatives by displacement of the halogen atom.     

Iodine catalyzed synthesis of the chromene derivatives in one-pot

Iodine catalyzed one-pot reactions of salicylaldehyde and dimolecular 1 H-indene-1,3(2H)-dione,barbituric acids,4-hydroxycoumarin, or 4-hydroxy-6-methylpyran-2-one were performed and provided a rapid,convenient and general approach to synthesize the chromene derivatives.2-(11-Oxo-10,11-dihydroindeno[l,2-b]chromen-10-yl)-1H-indene-1,3(2H)-diones P1-P4 and 10-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-3-methylpyrano[4,3-6]chromen-1(10H)-ones P8-P9 were unprecedentedly prepared and structurally identified by NMR and Mass.The confirmation of structure by single crystal X-ray crystallography is reported for P3.     

One-step reaction leading to new pyrazolo[1,5-a]pyrimidines by condensation of 2-pyrone with 5(3)-amino-3(5)-arylpyrazoles

Condensation of 5(3)-amino-3(5)-arylpyrazoles with 4-hydroxy-6-methylpyran-2-one leads to 5,7-dimethyl-2-arylpyrazolo[1,5-a]pyrimidines, 5-alkoxycarbonylmethyl-7-methyl-2-arylpyrazolo[1,5-a]pyrimidines and their isomeric 7-alkoxycarbonylmethyl-5-methyl-2-arylpyrazolo[1,5-a]pyrimidines. These compounds result from competitive reactions and from different cyclization pathways. Structure and mechanism of formation of these new products are reported.     

CAN-catalyzed synthesis of 10-arylpyrano[3,2-b]chromene-4,9-diones under solvent-free conditions

A novel and efficient one-pot synthesis of 10-aryl-7,8-dihydropyrano[3,2-b]chromene-4,9(6H,10H)-diones by three-component reaction of aromatic aldehydes, 5-hydroxy-2-methylpyran-4-one, and cyclic 1,3-dicarbonyl compounds in the presence of a catalytic amount of ceric ammonium nitrate under solvent-free conditions is described. The advantages of this method include operational simplicity, short reaction time, recyclable catalyst, and high yields.     

Cross-condensation of derivatives of cyanoacetic acid and carbonyl compounds. 2. One-pot synthesis of substituted 2-amino-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyrans in ethanol and ionic liquid [bmim][PF6]

The three-component reaction of 4-hydroxy-6-methylpyran-2(2H)-one with cyanoacetic acid derivatives and carbonyl compounds in EtOH or in the ionic liquid, viz., 1-butyl-3-methylimidazolinium hexafluorophosphate ([bmim][PF₆]), affords substituted 2-amino-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyrans. The yield of substituted pyrano[4,3-b]pyrans in [bmim][PF₆] is by 10—14% higher than that in EtOH.     

Heterocyclization of functionalized heterocumulenes with C,N-, C,O-, and C,S-binucleophiles: VIII. Synthesis of pyrano(chromeno)[3,4-e][1,3]oxazines by condensation of 1-chloroalkyl isocyanates with 4-hydroxy-6-methylpyran-2-one and 4-hydroxycoumarin

1-Chlorobenzyl isocyanates react with 4-hydroxy-6-methylpyran-2-one and 4-hydroxycoumarin forming 4-aryl-3,4-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]oxazine-2,5-diones. The reaction of 1-aryl-2,2,2-trifluoro-1-chloroethyl isocyanates with the above substrates gives rise to structurally isomeric 2-aryl-2-trifluoromethyl-2,3-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]-oxazine-4,5-diones.     

H_6P_2W_（18）O_（62）á18H_2O： A green and reusable catalyst for one-pot synthesis of pyrano[4,3-b]pyrans in water

A convenient,effcient and environmentally benign procedure has been developed for the synthesis of pyrano[4,3-b]pyran derivatives via a one-pot,three-component reaction of 4-hydroxy-6-methylpyran-2-one,aldehydes and malononitrile in water using H6P2W18O62á18H2O as catalyst.Reusability of the catalyst and reaction media,short reaction times and easy isolation of products are some added advantages of the present methodology.     

Synthesis and structure of (C=O→Si←O′=C′)bis(2-methyl-4-oxopyran-3-yloxy)difluoro-(λ<Superscript>6</Superscript>)siliconium

A new six-coordinate silicon compound, (C=O→Si←O′=C′)bis(2-methyl-4-oxopyran-3-yloxy)-difluoro(λ⁶)siliconium, containing two five-membered rings closed by C=O→Si coordination bonds, forms o protodesilylation trifluoro(phenyl)silane with 3-hydroxy-2-methylpyran-4-one (maltol). According to multinuclear NMR and IR spectral data and quantum-chemical calculations, the silicon atom in this compound has an octahedral environment with two cis-arranged C=O→Si bonds     

Near-infrared solid-state fluorescent naphthooxazine dyes attached with bulky dibutylamino and perfluoroalkenyloxy groups at 6- and 9-positions

No solid-state fluorescence is observed for 9-(diethylamino)benzo[a]phenoxazin-5-one (Nile Red). However, 9-dibutylamino-6-{perfluoro[4-methyl-3-(1-methylethyl)-2-penten]-2-oxy}benzo[a]phenoxazin-5-one showed fluorescence maximum at 717 nm in solid state with fluorescence quantum yield 0.024. X-ray crystallographic analysis suggests that prevention of network π−π interactions by the bulky fluorine-containing and dibutylamino groups is essential to show solid-state fluorescence.     

二氧化硫脲:一锅合成吡喃并[4,3-b] 吡喃类化合物的高效可重复使用有机催化剂（英文）简

A series of pyrano[4,3-b]pyran derivatives have been synthesized in excellent yields by the reaction of aromatic aldehydes with malononitrile or cyanoacetate and 4-hydroxy-6-methylpyran-2-one in water at 80℃, with the transformation being catalyzed by an aqueous solution of thiourea dioxide (TUD). Upon completion of the reaction, the product was isolated by filtration or extraction and the remaining aqueous TUD solution could be reused several times without any discernible impact on its catalytic activity. This procedure offers several advantages over existing procedures, including high yields, operational simplicity, the use of a non-toxic catalyst and solvent, short reaction time and minimum pollution of the environment, making it a useful and attractive process for the preparation of pyrano[4,3-b]pyran derivatives.     

The Synthesis of Novel Crown Ethers, Part VII [1]. Coumarin Derivatives of Benzocrowns and Cation Binding from Fluorescence Spectra

4-[3-(1-benzopyran-2-one)] derivativesof benzo[12]crown-4, benzo[15]crown-5 andbenzo-[18]crown-6 were synthesized from4-[3-(1-benzopyran-2-one)]-1,2-dihydroxy-benzenereacting with bis-ethyleneglycol dihalides orpentaethylene glycol ditosylate in alkali carbonate/DMF/water. The original products were identified byhigh resolution EI-mass spectra as well as IR,¹H-NMR and ¹³C-NMR spectroscopy. The 1 : 1binding constants of Mg²⁺, Li⁺, Na⁺ andK⁺ with the coumarin-benzocrowns were estimated usingfluorescence emission spectroscopy in acetonitrile.The complexing enhanced quenching fluorescence spectra(CEQFS) and complexing enhanced fluorescence spectra(CEFS) exhibited the ion binding powers due tocationic recognition rules of the macrocycles.     

Nonlinear fluorescence quenching of newly synthesized coumarin derivative by aniline in binary mixtures

The fluorescence quenching of newly synthesized coumarin (chromen-2-one) derivative, 4-(5-methyl-3-phenyl-benzofuran-2-yl)-6-chloro-chromen-2-one (MPBClC) by aniline in different binary solvent mixtures of benzene and acetonitrile have been reported by steady state fluorescence measurements. All the measurements were carried out at room temperature (296 K). A positive curvature from linearity was observed in the Stern–Volmer (S–V) plot in all the solvent mixtures. Various rate parameters for the fluorescence quenching have been determined by sphere of action static quenching model and finite sink approximation model. The results show that the positive curvature in the S–V plot is due to both static and dynamic quenching processes. Further, with the use of finite sink approximation model, it is concluded that these bimolecular reactions are diffusion-limited.     

Synthesis and fluorescence properties of novel benzo[a]phenoxazin-5-one derivatives

Thirteen, benzo[a]phenoxazin-5-one derivatives 3a-m were synthesized from 4-nitrosoaniline hydrochlorides 1a-m and ethyl 1,3-dihydroxynaphthoate 2 and their fluorescence properties were discussed in terms of the electronic effect of substituents. A coupling reaction was carried out with 6-carbethoxy-9-N-(2-hydroxyethyl)-N-methylamino-5H-benzo[a]phenoxazin-5-one (3k) and acetyl-DL-alanine to afford N-[(6-carbethoxy-5-oxo-5H-benzo[a]phenoxazin)-9-yl]-N-methylaminoethylene acetyl-DL-alanine ester (4).     

Quinazolines and 1,4-benzodiazepines. XLVI. Photochemistry of nitrones and oxaziridines

The cyclic nitrones 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide ( 5a ) and 1,3-dihydro-7-methylthio-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide ( 5b ) are photoisomerized to readily isolable oxaziridines, 7-chloro-4,5-epoxy-5-phenyl-1,3,4–5-tetrahydro-2H-1,4-benzodiazepin-2-one ( 6a ) and 4,5-epoxy-5-phenyl-1,3,4,5-tetrahydro-7-methylthio-2H-1,4-benzo-diazepin-2-one ( 6b ). Oxaziridine 6b upon further irradiation gave ring expansion and ring contraction products, 4,6-dihydro-2-phenyl-9-methylthio-5H-1,3,6-benzoxadiazocin-5-one ( 7b ) and 4-benzoyl-3,4-dihydro-6-methylthioquinoxalin-2(1H)-one ( 8b ) respectively. The ring contraction product, 4-benzoyl-6-chloro-3,4-dihydroquinoxalin-2(1H)-one ( 8a ), was obtained from irradiation of oxaziridine 6a .     

1,2,3,4-四氢喹啉-4-酮衍生物的线性及非线性光学性质

合成了一系列具有刚性结构的推拉型1,2,3,4-四氢喹啉-4-酮衍生物: 1-苄基-1,2,3,4-四氢喹啉-4-酮(BTHQ)、2-(1,2,3,4-四氢喹啉-4-叶立德)丙二腈(THQM)、1,6-二羰基久洛尼定(DOJ)和1,6-二(二氰甲烯基叶立德)久洛尼定(BDCJ).测定了其吸收光谱、单光子荧光光谱和双光子上转换荧光光谱. 这类化合物的单双光子荧光参数都存在着很强的、规则的溶剂效应, 表明分子激发态可能存在较大的极性. 它们的二氯甲烷溶液在800 nm飞秒激光(150 fs)照射下, 能够发射出很强的双光子上转换荧光. 采用非线性透过率法测得四个化合物的双光子吸收截面在0.83～23.95×10－50 cm4&#8226;s&#8226;photon－1之间. 这类化合物的激发态存在有效的分子内电荷转移, 对双光子吸收和双光子荧光发射有较大贡献.     

On the reactions of aroylacetonitriles with acetoacetates

2,7-Diaryl-3-cyano-4-methylpyrano[4,3-b]pyridin-5-ones were synthesized by Ni(acac)₂-catalyzed condensation of aroylacetonitriles with acetoacetates. The competitive Knoevenagel reaction gave 6-aryl-5-cyano-4-methylpyran-2-ones as by-products. A preparative method for the synthesis of the latter compounds in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst was proposed.