Synthesis of 2-acylcyclohexane-1,3-diones through tetrahydrobenzisoxalones

A new method was developed for the synthesis of 2-acylcyclohexane-1,3-diones from the adducts of 1,3-dipolar cycloaddition of nitrile oxides to cyclohexenones. The method is examined in the case of the preparation of 2-acetyl-,2-enanthoyl-, and 2-benzoyldimedone.     

A convenient one-pot synthesis of substituted 2-pyrone derivatives

2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time.     

1,3-Dimercaptopropyl-2-thiopyrimidines

Reaction of 2-phenyl-1,3-dithiane-5-isothiuronium bromide with halopyrimidines gives 5-pyrimidylthio-1,3-dithianes and 1,3-dimercaptopropyl-2-thiopyrimidines. Some derivatives have been isolated and characterized. The complexing ability of the 1,3-dimercapto-2-thiopyrimidines has been examined by the metallic indicator method.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 605–610, May, 1970.     

Synthesis of 2-substituted benzo-1,3-ditelluroles

A method for the synthesis of 2-phenylbenzo-1,3-ditellurole by the reaction of disodiumo-benzeneditellurolate with benzylidene chloride was proposed. 2-Methylbenzo-1,3-ditellurole and benzo-1,3-ditellurole-2-carboxylic acid were prepared by the reaction of 2-lithiobenzo-1,3-ditellurole with MeI and CO₂, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1132–1134, June, 2000.     

Superoxide anion-scavenging effect of 2-amino-1,3-selenazoles

We investigated the superoxide anion scavenging effects of thirteen 2-amino-1,3-selenazoles using a highly sensitive quantitative chemiluminescence method. At 166 microM, the 2-amino-1,3-selenazoles scavenged in the range of 14.3 to 96.7% of O2-. 2-Piperidino-1,3-selenazole and 4-phenyl-2-piperidino-1,3-selenazole exhibited the strongest superoxide anion-scavenging activity among the 2-amino-1,3-selenazoles. The 50% inhibitory concentrations (IC50) of 2-piperidino-1,3-selenazole and 4-phenyl-2-piperidino-1,3-selenazole were determined to be 4.03 microM and 92.6 microM, respectively. Thus, these compounds acted in vitro as effective O2- scavengers.     

New Approach to the Synthesis of 1,3-Chloroisothiocyanatoalkanes. Synthesis of Tetrahydro-1,3-thiazine-2-thiones and 2-Alkylamino-5,6-dihydro-1,3-thiazines

A method was developed to prepare 1,3-chloroisothiocyanatoalkanes by reducing 1,3-isothiocyanato ketones using sodium borohydride at pH ~7 and subsequent treatment of the resultant 1,3-isothiocyanato alcohols with thionyl chloride. The reaction of 1,3-chloroisothiocyanatoalkanes with sodium hydrosulfide or amines gives substituted tetrahydro-1,3-thiazine-2-thiones or 2-amino-5,6-dihydro-1,3-thiazines.     

3-丙烯酰基-1,3-噁唑烷-2-酮的合成

3-α,β-不饱和酰基-1,3-噁唑烷-2-酮在烷基化及Diels-Alder等反应中在手性催化剂的存在下,产物都有较高的对映选择性。但3-丙烯酰基-3,3-噁唑烷-2-酮极易聚合,现有制备方法结果均不理想。本文将丙烯酸与丙烯酰氯在三乙胺的存在下生成酸酐,再在无水氯化锂的作用下与1,3-噁唑烷-2-酮在室温反应,反应结束后直接将反应混合物通过硅胶柱色谱进行层析分离得到3-丙烯酰基-1,3-噁唑烷-2-酮,产率达83％。合成路线如下：     

On the preparation of 2-halo alkyl substituted 1,3-dioxolanes and 1,3-dioxanes

Several methods for the preparation of 2-perfluoromethyl-substituted 1,3-dioxolanes and 1,3-dioxanes were tried. The method of Nerdel for the preparation of 1,3-dioxolanes, making use of the condensation between carbonyl compounds and oxiranes, was found to be suitable for perhalogenated ketones and aldehydes, and may even be extended to oxetanes, affording 2-perhaloalkylated 1,3-dioxanes.The yield of the cyclic acetals drops with inreasing substitution.     

Determination of molybdenum(VI) by differential pulse polarographic technique using 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D)

A novel analytical reagent 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D) was synthesized for the determination of molybdenum(VI). The present paper reveals the detailed study of electroanalytical behaviour for [Mo-(4-2-HPEDB-1,3,D)] complex under optimized conditions. The peak obtained for [Mo-(4-2-HPEDB-1,3,D)] prevent the interference of foreign ions which shows the sensitivity of the proposed method. The linearity was maintained at the concentration range of 0.5–200 μg/mL at pH 4.5 with correlation factor 0.9997. The present method was successfully applied for the analysis of molybdenum(VI) in biological fluids and plant material. The results obtained from the proposed method show good agreement with reference method.     

Synthesis of 2-phenylethynyl-1,3-dioxanes and their hydrolysis

2-Phenylethynyl substituted 1,3-dioxanes were obtained by the reaction of 1,3-dioxanium salts with an lotsich reagent. It was shown that they are readily hydrolyzed with the formation of a-acerylenic ketones. A simple new method is proposed for the synthesis of the latter without isolating the intermediate 1,3-dioxanes using the reaction of 4 substituted 2-methyl(phenyl, furyl)-1,3-dioxanium salts with hydroxymethyl- and phenylethynylmagnesium bromide as examples.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 193–197, February, 1996.     

Cu(OTf)2 catalyzed cross-coupling reaction of 1,3-dicarbonyl derivatives with 2-oxo-1-pyrrolidine compounds

An efficient method for the cross-coupling reactions of 1,3-dicarbonyl compounds with 2-oxo-1-pyrrolidine compounds 1 was developed. Cu(OTf)₂ catalyzed C–C bond forming reactions using substrates 1 with 1,3-dicarbonyl compounds in chloroform, providing the corresponding compounds of 2-oxo-1-pyrrolidine bearing 1,3-dicarbonyl moiety in moderate to good yields.     

Synthesis of 2-hetaryl-2-(tetrahydrofuran-2-ylidene)acetonitriles

The reaction of azolylacetonitriles with γ-chlorobutyryl chlorides gave the corresponding 2-(1-R-1,3-di- hydro-2H-benzimidazol-2-ylidene)-, 2-(1,3-benzothiazol-2-ylidene)-, and 6-chloro-2-(4-methylthiazol-2-ylidene)-3-oxohexanenitriles. A study of the intramolecular cyclization of 2-(quinazolin-2-ylidene)-3-oxo-6-hexanenitriles and -heptanenitriles has led to the development of an efficient method for the preparation of 2-(quinazolin-2-yl)-2-(tetrahydrofuran-2-ylidene)acetonitriles. The (Z,E)-isomerism of the synthesized 2-hetaryl-2-(tetrahydrofuran-2-ylidene)acetonitriles was studied.     

[2+2] Cycloaddition of 1,3‐Dienes by Visible Light Photocatalysis

[2+2] Photocycloadditions of 1,3‐dienes represent a powerful yet synthetically underutilized class of reactions. We report that visible light absorbing transition metal complexes enable the [2+2] cycloaddition of a diverse range of 1,3‐dienes. The ability to use long‐wavelength visible light is attractive because these reaction conditions tolerate the presence of sensitive functional groups that might be readily decomposed by the high‐energy UVC radiation required for direct photoexcitation of 1,3‐dienes. The resulting vinylcyclobutane products are poised for a variety of further diversification reactions, and this method is consequently expected to be powerfully enabling in the synthesis of complex organic targets.     

Potassium fluoride-promoted reaction of (2-chloro-2-nitroethenyl)benzenes with 1,3-dicarbonyl compounds. A general synthesis of 6,6-dimethyl-2-nitro-3-phenyl-3,5,6,7-tetrahydro-4(2H)benzofuranones and some analogs

A convenient procedure to prepare in good yields 6,6-dimethyl-2-nitro-3-phenyl-3,5,6,7-tetrahydro-4(2H)-benzofuranones starting from (2-chloro-2-nitroethenyl)benzenes and 5,5-dimethyl-1,3-cyclohexanedione in the presence of potassium fluoride is reported. This method also proved efficient with other 1,3-dicarbonyl compounds, and has been successfully extended to 1,3-cyclohexanedione, 2,5-pentanedione, dibenzoylmethane and ethyl acetoacetate.     

Zur Bestimmung von Carbamaten 2-(1,3-Dioxolan-2-yl)-phenyl-N-methyl-carbamat in Reaktionsgemischen

Zusammenfassung Am Beispiel von 2-(1,3-Dioxolan-2-yl)-phenyl-N-methyl-carbamat werden Hydrolyse-bedingungen und spezifische Bestimmungsverfahren für Carbamate beschrieben. Besonders günstig verläuft die Hydrolyse unter Verwendung von Kaliumhydroxid in Propylenglykol oder von konz. Phosphorsäure. Wegen der erhöhten Reaktionstemperaturen verlaufen die Reaktionen rasch.Eine für 2-(1,3-Dioxolan-2-yl)-phenyl-N-methyl-carbamat gültige Bestimmungsmethode beruht auf der Umsetzung des Acetalringes mit Hydroxylaminhydrochlorid [8]; es entsteht direkt das entsprechende Oxim. Möglicherweise vorhandene Nebenprodukte, welche die gleiche Reaktion geben, sind Salicylaldehyd und 2-(1,3-Dioxolan-2-yl)-phenol; sie lassen sich colorimetrisch als Eisen(III)-Komplexverbindung bestimmen.

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The determination of carbamates. 2-(1,3-dioxolane-2-yl)-phenyl-N-methyl-carbamate in reaction mixtures

Hydrolysis procedures for carbamates have been investigated, using 2-(1,3-dioxolane-2-yl)-phenyl-N-methyl-carbamate as an example. Phosphoric acid (85% w) and potassium hydroxide in propylene glycol are suitable hydrolyzing agents. Due to the elevated reaction temperature, hydrolysis is fast.A method applicable to the determination of 2-(1,3-dioxolane-2-yl)-phenyl-N-methyl-carbamate is based on direct conversion of the acetal group to the related oxime, with hydroxylamine hydroehloride as reagent.Salicyl aldehyde and 2-(1,3-dioxolane-2-yl)-phenol, which are potential by-products, give the same reaction. They form a coloured iron(III)-complex and can thus be determined.

     

New approach to the synthesis of cyclic 1,3-dithioacetals from thiophene-2-carbaldehydes

A highly selective method was developed for preparation of previously unknown 1,3-dithiolanes and 1,3-dithianes by reactions of thiophene-2-carbaldehyde and its analogs with alkanedithiols under the action of trimethylchlorosilane.     

高效液相色谱-电感耦合等离子体质谱法测定化妆品中2-溴-2-硝基-1,3-丙二醇

建立了高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)测定化妆品中2-溴-2-硝基-1,3-丙二醇的方法。采用ZORBAX RX-C_8色谱柱(150×2.1 mm,5μm)进行分离,以甲醇-水-5%磷酸(10∶985∶5,用2 mol/L NaOH调至pH 3.0)为流动相,流速为0.7 m L/min,柱温为室温。结果显示,2-溴-2-硝基-1,3-丙二醇在2.5 min处出峰,其线性范围为0.01~1.0 mg/L,相关系数为0.999 9。不同基质化妆品的方法检出限均为1.0μg/g,回收率为94.6%~101.3%,相对标准偏差(RSD,n=6)为1.5%~4.5%。该方法快速、准确、灵敏、无干扰,适用于化妆品中2-溴-2-硝基-1,3-丙二醇的定性定量测定。     

Diastereoselective synthesis of 2-phenylselenenyl-1,3-anti-diols and 2-phenylselenenyl-1,3-anti-azido-alcohols via hydroxy and azido-selenenylation reactions

A method to synthesize 2-phenylselenenyl-1,3-anti-diols and 2-phenyl- selenenyl-1,3-anti-azidoalcohols via hydroxy- or azido-selenenylation of trans-allylic alcohols is reported. Moreover, the first example of hydroxyl-selenenylation of an allylic azide is presented. Yields ranging from moderate to good and diastereomeric ratios up to 95:5 are achieved.     

Isomerization of 2-trichloromethyl-4-methylene-1, 3-dioxolanes

The thermal isomerization of 2-trichloromethyl-4-methylene-1,3-dioxolanes was studied. This reaction may serve as a convenient method for the preparation of 2-trichloromethyl-4-methyl-5-alkyl(aryl)-1,3-dioxols.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 446–449, April, 1973.     

Selective monobenzoylation of 1,2- and 1,3-diols catalyzed by Me2SnCl2 in water (organic solvent free) under mild conditions

We have developed an efficient method for selective monobenzoylation of 1,2- and 1,3-diols in water catalyzed by Me(2)SnCl(2). Treatment of 1,2- and 1,3-diols with benzoyl chlorides, DMT-MM, and potassium carbonate in the presence of a catalytic amount of Me(2)SnCl(2) and DMAP in water at room temperature gave monobenzoates in up to 97% yield.