Solvolytic and Thermolytic Reactions of Heterocyclic Pentacoordinate Silicon Compounds

When cyclic pentacoordinate SiCl compounds of the type A are reacted with methanol or water substitution of the SiCl bond and ring opening with cleavage of the SiN bond takes place with formation of tetracoordinate Si compounds. These compounds undergo an interesting thermal reaction resulting in a partial reformation of the cyclic pentacoordinate starting compounds A .     

类杯芳烃孔穴桥联双芘分子开关化合物

利用构型可变的分子开关类杯芳烃孔穴化合物(Cavitand)作为母体,合成了2种具有不同臂长的双芘Cavitand化合物.在室温及中性状态下,2种双芘Cavitand化合物均可检验出分子内激基复合物荧光,其中短臂双芘Cavitand化合物的荧光明显强于长臂Cavitand化合物.经三氟乙酸酸化后,2种双芘化合物的分子内激基复合物荧光消失;而继续使用碱中和至中性,则荧光恢复.这个荧光出现-消失-出现的过程验证了Cavitand母体化合物分子构型闭合-打开-闭合可有效调控分子激基复合物荧光开关过程.此外,通过高斯计算模拟了2种化合物的理论分子构型,发现长臂双芘化合物在Cavitand母体构型处于闭合状态时2个芘基团重叠部分较少是其分子内激基复合物荧光较弱的关键原因.     

Reactions of Sulfenamides with Compounds of Trivalent Phosphorus

Chloro-dimethylamino-phenyl-p-tolylthio-phosphonium chloride 2 , dimethylamino-diphenyl-p-tolylthio-phosphonium chloride 3 , bis(diethylamino)-dimethylamino-p-tolylthiophosphonium chloride 4 and tert-butyl-dimethylamino-phenyl-p-tolylthio-phosphonium chloride 5 were prepared by the reaction of N,N-dimethylamino-p-tolylsulfenamide 1 with PhPCl₂, Ph₂PCl, (Et₂N)₂PCl and ^tBu(Ph)PCl, respectively. The reaction of N,N′-dimethyl-N,N′-bis(trimethylsilyl)urea 9 and N-methyl-N′-phenyl-N,N′-bis(trimethylsilyl)urea 10 with phenylsulfenyl chloride 6 or p-nitrophenylsulfenyl chloride 8 furnished the N-arylthio-N,N′-diorgano-N′-(trimethylsilyl)-ureas 11 – 14 . The reaction of 11 – 14 and of the previously known compounds 15 and 16 with MePCl₂, ClCH₂PCl₂, ^tBuPCl₂ and PhPCl₂ resulted in the formation of the 2-arylthio-2-chloro-1,2,3-triorgano-1,3,2λ⁵-diazaphosphetidin-4-ones 17 – 26 . 1,3-Dimethyl-2-(1,1,1,3,3,3-hexafluoro-2-propoxy)-2-phenyl-2-phenylthio-1,3,2λ⁵-diazaphosphetidin-4-one 29 and the 2-arylthio-1,3-dimethyl-2-(p-nitrophenoxy)-2-organyl-1,3,2λ⁵-diazaphosphetidin-4-ones 30 – 32 were obtained in the reactions of compounds 17, 24 and 27 with 1,1,1,3,3,3-hexafluoro-2-propanol or p-nitrophenol in the presence of triethylamine. The reaction of compound 21 with thiophenol in the presence of triethylamine resulted in a mixture of products, from which 1,3,4,5,7-pentamethyl-1,3,5,7-tetraaza-4λ⁵-phosphaspiro[3.3]heptan-2,6-dione 33 was isolated. The identity and structure of all the new compounds were established by ¹H-, ¹³C- and ³¹P-NMR spectroscopy and by elemental analysis. A possible mechanism of reaction of sulfenamides with compounds of trivalent phosphorus is discussed. For the compounds 5a, 32 and 33 X-ray structure analyses were conducted. The cation of compound 5a involves four-coordinate phosphorus (essentially tetrahedral geometry) and is a rare example of a P–S single bond in such a system (P–S 207.37(9) pm). In 32 the geometry at phosphorus is distorted trigonal bipyramidal, with axial positions occupied by oxygen and nitrogen atoms. In the spirophosphorane 33 the geometry at phosphorus is intermediate between trigonal bipyramidal and square pyramidal, with essentially planar four-membered rings.     

Synthesis of a New Class of Highly Functionalized Phosphorus Ylides Containing Heterocyclic Compounds

The zwitterionic intermediate generated from the reaction of triphenylphosphine with electron deficient acetylenic compounds was trapped by various NH acids. The synthesis resulted in a new class of highly functionalized heterocyclic compounds. Some of the reactions produced E and Z isomers. And the stability and transformation of them were studied by dynamic ¹H NMR and density functional theory (DFT) calculations.     

Heterocyclic Aminoboron Compounds as Antituberculosis Agents

We have examined six boron compounds for their potential antituberculosis activities. Addition of 2‐formylphenyl pinacol boronate ester to tetraamine derivatives gave three new aminoboron compounds, which were elementally pure when obtained, and one example was characterized by a single crystal X‐ray diffraction study. Heterocyclic aminoboron compounds 1–4 showed moderate degrees of antimycobacterial activity against Mycobacterium tuberculosis.     

新型手性磷化合物的合成及其作为配体催化剂在某些不对称合成反应中的应用

从L-氨基酸、D-樟脑、(-)-假麻黄碱、(-)-α-苯乙胺、(S)-(-)-联萘二酚等旋光源出发,合成了26个三配位及四配位手性磷化合物.作为配体催化剂,试验了它们在潜手性酮及亚胺的不对称硼烷还原反应、醛与二乙基锌的不对称烷基化反应以及醛的不对称硅腈化反应中的催化活性.发现其中有些催化剂有很好的立体选择性.     

New Synthetic Route and Characterisation of Phosphorus and Arsenic Heterocyclic Compounds

Herein we report synthetic routes for the preparation of 2-chloro-1,3,2-dioxarsenane 1 , O,O'-bis(5,5-dimethyl-1,3,2-dioxarsenane)-2,2-dimethyl-1,3-propanediol 3 , 2-chloro-1,3,2-dioxaphosphorinane 4 , and 2-fluoro-1,3,2-dioxaphosphorinane 5 . The new synthetic routes described here have the advantage to be simple, very clean and to lead to the desired compounds in very good yields. Compound 2-fluoro-1,3,2-dioxarsenane 2 also was prepared in good yield and is described here for the first time. Compounds 1-5 were fully characterized on the basis of NMR spectroscopic studies. Semi-empirical structural studies have been carried out and the results show that 1 and 2 exist as a mixture of two conformers, whereas only one conformer for 4 and 5 have been found. Variable temperature 1 H NMR studies reveal a fluxional behaviour for 1 and a mechanism for the inter-conversion between its two conformers is proposed.     

Photocatalytic Redox Reactions for In‐Source Peptide Fragmentation

In‐source oxidation : In‐source photocatalytic redox reactions for inducing peptide fragmentation are achieved on a TiO₂‐derived target plate during laser desorption ionization mass spectrometry in the presence of samples and glucose acting as both an electron donor and a hole conductor (see scheme).

     

含磷五元环五配位化合物的合成

三配位磷化物与烷氧基苯硫醚反应合成了一系列含磷五元环的五配位化合物。在不同温度下,测定了这些化合物的¹⁹FNMR。化合物(7)与三氟乙氧基苯硫醚反应生成化合物(19)以及(20)和(21);化合物(11)与六氟异丙氧基苯硫醚反应生成化合物(18)和(21),并对这些反应机理进行了讨论。     

Grapevine as a Rich Source of Polyphenolic Compounds

Grapes are rich in primary and secondary metabolites. Among the secondary metabolites, polyphenolic compounds are the most abundant in grape berries. Besides their important impacts on grape and wine quality, this class of compounds has beneficial effects on human health. Due to their antioxidant activity, polyphenols and phenolic acids can act as anti-inflammatory and anticancerogenic agents, and can modulate the immune system. In grape berries, polyphenols and phenolic acids can be located in the pericarp and seeds, but distribution differs considerably among these tissues. Although some classes of polyphenols and phenolic acids are under strict genetic control, the final content is highly influenced by environmental factors, such as climate, soil, vineyard, and management. This review aims to present the main classes of polyphenolic compounds and phenolic acids in different berry tissues and grape varieties and special emphasis on their beneficial effect on human health.     

Synthesis of Heterocyclic Pentavalent Phosphorus Compounds from Phosphite Derivatives and Indane-1,2,3-Trione

Reaction of trialkylphosphite derivatives with indane-1,2,3-trione proceeds smoothly at room temperature to afford the corresponding heterocyclic pentavalent [P(V)] phosphorus compounds via an intermolecular [4+1] cycloaddition reaction in excellent yields under solvent-free conditions. We also used dimethylphosphite and diethylphosphite instead of trialkylphosphites in this reaction, but the corresponding pentavalent phosphorus compounds were not isolated, and in both cases phosphate derivatives were obtained. The structures of the products were deduced from their IR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectra, and mass spectrometry.     

Domino Reactions of 3‐Vinylchromone Leading to Different Heterocyclic Compounds

A range of heterocyclic systems incorporating chromone and related scaffolds was synthesized via domino reactions of 3‐vinylchromone. These cascade processes resulted in the construction of various heterocyclic nuclei such as xanthone and enaminone as well as diazolo and triazolo chomenopyrimidine heterocycles.     

Unusual Transformations of 2-Cyanoacrylates in Reactions with Trivalent Phosphorus Compounds

Abstract

Cyanoacrylates 1 have existed for 40 years, but up till ¹ only polymerization processes, effected by various nucleophiles, including trivalent phosphorus compounds, have been known. We have shown that under established conditions 1 (aR=Me, b R=Et) reacts with trivalent phosphorus compounds not only via the anionic polymerization pathway, but depending on the structure, it forms stable adducts2,4 or 5.     

Displacement Reactions of Phosphorus(V) Compounds and Their Pentacoordinate Intermediates

Reactions of phosphorus(v) compounds involving the mutual interconversion of tetra- and pentacoordinate species are discussed in a critical review emphasizing stereochemical implications of the reaction mechanism. This discussion includes the formation and decomposition of the stable oxyphosphoranes, the Michaelis-Arbusov, Perkov, and Wittig reactions, interconversions of phosphines and their oxides, and the nucleophilic displacements on phosphonium compounds. Reactions of phosphate esters and related compounds receive particular attention. All chemical arguments are derived by considering the effect of factors determining the relative stabilities of phosphorane derivatives, their rates of formation, decomposition and rearrangement by bond deformation or rupture and recombination processes, considerations which are uniformly applied on the basis of concepts developed in a preceding communication^[2]. It is shown that a comprehensive mechanistic interpretation of the foregoing reactions requires substantial addition to available conceptual foundations such that, in many cases, present concepts and mechanisms must be revised.     

Heterocyclic amino acids as synthons. Reactions with dicarbonyl compounds

From some alkyl heteroarylglycinates and dicarbonyl compounds various heterocyclic systems are easily accessible. Transformations are described which lead to imidazo[1,5-α]pyridines, heteroaryl-substituted pyrroles, pyrido[1,2-α]pyrazines, pyrido[1,2-α]pyrimidines or quinolizin-4-ones.     

Microalgae as a Source of Valuable Phenolic Compounds and Carotenoids

Microalgae are photosynthetic, eukaryotic organisms that are widely used in the industry as cell factories to produce valuable substances, such as fatty acids (polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), sterols (sitosterol), recombinant therapeutic proteins, carbohydrates, vitamins, phenolic compounds (gallic acid, quercetin), and pigments (β-carotene, astaxanthin, lutein). Phenolic compounds and carotenoids, including those extracted from microalgae, possess beneficial bioactivities such as antioxidant capacity, antimicrobial and immunomodulatory activities, and direct health-promoting effects, which may alleviate oxidative stress and age-related diseases, including cardiovascular diseases or diabetes. The production of valuable microalgal metabolites can be modified by using abiotic stressors, such as light, salinity, nutrient availability, and xenobiotics (for instance, phytohormones).     

Reactions of N-(2,2-Dichloro-2-phenylethylidene)arenesulfonamides with Aromatic and Heterocyclic Compounds

Benzene, toluene, and 2-chlorothiophene regioselectively react with N-(2,2-dichloro-2-phenyl- ethylidene)arenesulfonamides in the presence of oleum to give N-[1-aryl(or hetaryl)-2,2-dichloro-2-phenylethyl]arenesulfonamides. Analogous C-amidoalkylation products are formed by the action of N-(2,2-dichloro- 1-hydroxy-2-phenylethyl)- and N-(1-arylsulfonylamino-2,2-dichloro-2-phenylethyl)arenesulfonamides on toluene and 2-chlorothiophene in concentrated sulfuric acid.