Efficient synthesis of pyrroles and 4,5,6,7-tetrahydroindoles via palladium-catalyzed oxidation of hydroxy-enamines

Facile and one-pot synthetic route of poly-substituted pyrroles and 4-oxo-4,5,6,7-tetrahydroindoles is established, which consists of three steps: (1) palladium-catalyzed oxidation of hydroxy-enamines by using tetrakis(triphenylphosphine)palladium and mesityl bromide oxidation system, (2) intramolecular cyclization, and (3) dehydration.     

Tetracyanoethylation and fischer rearrangement of some 4-oxo-4,5,6,7-tetrahydroindoles

The reaction of the 1,2-diaryl-4-oxo-4,5,6,7-tetrahydroindoles, and 3-methyl-4-oxo-4,5,6,7-tetrahydroindole with tetracyanoethylene occurred at the 5 position of the tetrahydroindole ring. A Fischer rearrangement of the phenylhydrazones of these 4-oxotetrahydroindoles gave pyrrolo [2,3-c]carbazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 217–221, February, 1986.     

Chemo- and regioselective ethynylation of 4,5,6,7-tetrahydroindoles with ethyl 3-halo-2-propynoates

4,5,6,7-Tetrahydroindoles undergo a rapid, facile (rt, 60 min) ethynylation with ethyl 3-halo-2-propynoates upon grinding with solid K₂CO₃ (without solvent) at C-2 of the tetrahydroindole ring to afford ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)-2-propynoates in 62–90% yield.     

Aminomethylation of substituted 5-hydroxypyrimidines

Conditions that make it possible to obtain aminomethyl derivatives of 2-R-4,6-dimethyl-5-hydroxypyrimidine that are substituted both in the pyrimidine ring (R = H) and at the methyl group of the side chain (R = H, CH₃, C₆H₃) were found. The facts established in this research make it possible to propose various substitution mechanisms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–683, May, 1980.     

Aminomethylation of formononetin and cladrin by primary amines

The reaction of natural isoflavones formononetin and cladrin with primary amines and formalin in the presence of a base catalyst was studied. Several novel substituted 9,10-dihydro-4H,8H-chromeno [8,7-e][1,3]oxazin-4-ones containing alkyl, benzyl, or heterylalkyl substituents in the N-9 position were synthesized.     

Thermochemistry of substituted pyrroles

The heats of solution of a series of substituted pyrroles in benzene, carbon tetrachloride, chloroform, DMF, and pyridine were measured by a calorimetric method at 298.15 K. The influence of substituents in the pyrrole molecule on the energy parameters of solvation by organic solvents is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 495–499, March, 1993.     

A palladium- and copper-free cross-coupling of ethyl 3-halo-2-propynoates with 4,5,6,7-tetrahydroindoles on alumina

Ethyl 3-halo-2-propynoates undergo facile (no heating, no base, no solvent) palladium- and copper-free cross-coupling with 4,5,6,7-tetrahydroindoles on alumina to afford the corresponding 4,5,6,7-tetrahydroindole-2-propynoates in 46% and 71% yields. The yield of the by-products [ethyl 3,3-di(4,5,6,7-tetrahydro-1H-indol-2-yl)acrylates] under appropriate conditions can reach 79%.     

Efficient synthesis of substituted pyrroles through iron-mediated oxidation reaction of 3-methylenehexane-2,5-dione with primary amines

An efficient route has been developed for the synthesis of multiple substituted pyrrole derivatives from the readily available agents through iron-mediated oxidative aromatization process in good to excellent yields. This method is well tolerated with a diverse broad range of substrates and a complementary approach to currently available synthetic methods.     

Synthesis of arylsulfonyl substituted pyrroles

The cycloaddition reaction of symmetrically and unsymmetrically substituted munchnones with arylsulfonyl alkynes has been studied. The reaction affords pyrrole derivatives whose structures were assigned on the basis of spectroscopic data. The distribution of regioisomers observed in the case of unsymmetrically substituted munchnones is discussed.     

Simple synthesis of substituted pyrroles

Simple synthesis of substituted pyrroles using iodine-catalyzed and montmorillonite KSF-clay-induced modified Paal-Knorr methods has been accomplished with excellent yields. N-Substituted carbazole has also been prepared by following this method. If one of the reactants is a liquid, the reaction proceeds exceedingly well without a solvent. This method gives pyrroles with less nucleophilic multicyclic aromatic amines at room temperature.     

IR spectra of substituted pyrroles

The IR spectra of 52 substituted pyrroles, including 24 1-vinylpyrroles, were thoroughly analyzed. The principal analytical bands of the pyrrole ring and the vinyl group were isolated. Doublet character of the bands of the stretching vibrations of the double bond ( ^v C=C) and the C-H (CH₂=) out-of-plane deformation vibrations, which indicates the presence of rotational isomerism relative to the N-vinyl bond, was detected. The integral intensify of the principal component of the ^v C=C doublet was measured for 12 of the 1-vinylpyrroles, and it is shown that it is practically independent of the structure of the alkyl substituents in the ring. Proof for the existence of a nonplanar gauche conformation for the 1-vinylpyrroles was obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 910–914, July, 1977.     

Interactions of iron with biogenic amines and ATP

Studies on the chelation of iron(II) with a number of individual monoamines and adenosine-5-triphosphate (ATP) were carried out potentiometrically in aqueous model systems at 25·0±0·1°C and an ionic strength of 1·0 (KNO₃). The nature of interaction of phosphatidylserine (a membrane-bound phospholipid) with Fe(II) was also investigated. In the combined presence of ATP and the amines, Fe(II) ion was found to be chelated to both the ligands in the pH range 6·8–7·2 which is of biological interest. The binding constants (log K) for the coordination of the amines with Fe(II)-ATP are reported for norepinephrine (NE), dopamine (DA), octopamine (OA), tyramine (TA), p-hydroxyamphetamine (p-HAA), norephedrine (NEph), p-hydroxynorephedrine (p-HNEph) and normetanephrine (NMeN), and the values ranged from 3·78 to 7·98. The reactions of a number of other biogenic amines with Fe(II) in the pH range 3–10·5 are postulated on the basis of equilibrium data generated in this study. Phosphatidylserine (PS) was found to coordinate with Fe(II)-ATP to form the ternary chelate, Fe(II)-ATP-PS, in the pH range 5–6·5. NE exhibited strong binding with the Fe(II)-ATP-PS system in the pH range 6·5–8·5.     

Enzymatic determination of biogenic amines with transglutaminase

Tyramine, histamine, putrescine and cadaverine, the most common biogenic amines indicating the food quality, were studied in the transglutaminase-catalyzed reaction. Transglutaminase (protein-glutamine gamma-glutamyltransferase EC 2.3.2.13) catalyzes an acyl transfer reaction between a donor substrate and an acceptor substrate (e.g. biogenic amine) and forms a cross-linkage between substrates with a release of ammonia. The reaction can be monitored by measuring the ammonia produced in the reaction. The concentration of produced ammonia was found to be proportional to the concentration of biogenic amine and could hence be used to determination of biogenic amines in food matrixes.     

Synthesis of substituted pyrroles from ketones

A number of substituted pyrroles have been prepared through a four step reaction sequence based on the regiospecific alkylation of N,N-dimethylhydrazones with 2-iodomethyl-1,3-dioxolane.     

基于核酸适配体信号置换结合循环扩增的液相色谱法检测4种生物胺

生物胺的含量是衡量食品卫生状况和药物纯度的重要标志之一,建立食品药品中生物胺的精准、灵敏检测具有重要的实际意义。该文基于核酸适配体置换生物胺信号源并结合荧光信号循环扩增的策略,建立了一种新型的同时检测鱼肉、猪肉和抗生素中4种生物胺的高效液相色谱法(HPLC)。首先通过两步信号置换,将无荧光信号的目标物转换为有荧光信号的核酸探针;再结合双链特异性核酸酶辅助信号扩增策略,获取大量不同长度和碱基序列的核酸探针;最后借助HPLC平台实现实际样品中多种生物胺信号的精确识别。文章研究了核酸探针的碱基序列和长度对出峰时间和前后顺序的影响,以提高荧光信号的区分度。通过正交实验探讨了柱温、流速和梯度洗脱过程、反应温度、孵化时间等对信号分离的影响,确定最优条件,提高信号的分离效率。该方法对目标物酪胺、组胺、精胺和色胺的检出限分别为0.25、0.21、0.27和0.19 pmol/L,线性范围为1 pmol/L~1 μmol/L。通过对硫酸大庆霉素、鱼肉和猪肉样品中生物胺含量进行检测,研究了该方法检测实际样品的可行性。该方法可精准识别、捕获和分离复杂基质样品中的生物胺组分,能有效提高对目标分析物的选择性,并降低实际样品中的基质干扰,有望为食品药品分析领域提供一种新的思路。     

Oxazolidines. 1. Basic catalytic disproportionation of cyclohexanospiro-2-oxazolidines: Synthesis of N-substituted 4,5,6,7-tetrahydroindoles

It has been shown that the basic catalytic disproportionation of cyclohexanospiro-2-oxazolidines in the presence of potassium hydroxide or sodium methylate leads to N-substituted 4,5,6,7-tetrahydroindoles with a yield of up to 73%. The influence of the character of substituents at the nitrogen atom of oxazolidine on the course of the reaction has been established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 533–535, April, 1986.     

Fluorometric sensing of biogenic amines with aggregation-induced emission-active tetraphenylethenes

A fluorometric sensor for detection and identification of biogenic amines with carboxylic acid modified tetraphenylethenes (TPEs) based on aggregation-induced emission (AIE) is reported. A mixture of the carboxylic acid substituted TPE and biogenic amines displayed a blue emission on aggregation, which serves as a "turn-on" fluorescent sensor for the amines, the degree of fluorescence enhancement being dependent on the amine. The chromic responses were utilized to distinguish the amines. A fluorometric sensor array of three TPEs with carboxylic acid groups was shown to identify accurately 10 different amines, including biogenic amines. The response patterns were systematically classified by using linear discriminant analysis (LDA) with 98% classification accuracy. Additional information on the concentration of histamine in a "tuna fish matrix" as an example was assessed by the further analysis of the fluorescence intensity, demonstrating a test for food freshness and quality.     

One-pot three-component catalytic synthesis of fully substituted pyrroles from readily available propargylic alcohols, 1,3-dicarbonyl compounds and primary amines

A simple and highly efficient method for the preparation of fully substituted pyrroles, from readily accessible secondary propargylic alcohols, 1,3-dicarbonyl compounds and primary amines, has been developed. The one-pot multicomponent reaction, which is catalysed by the system [Ru(eta(3)-2-C(3)H(4)Me)(CO)(dppf)][SbF(6)]/CF(3)CO(2)H (dppf: 1,1'-bis(diphenylphosphanyl)ferrocene), involves initial propargylation of the 1,3-dicarbonyl compound promoted by CF(3)CO(2)H and subsequent condensation between the resulting gamma-keto alkyne and the primary amine to afford a propargylated beta-enamino ester or ketone, which undergoes a ruthenium-catalysed 5-exo-dig annulation to form the final pyrrole.