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Indium (III) Choloride Catalyzed One Step Synthesis of Some New Dibenzo(D,F)(1,3)Dioxepine
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Zinc Oxide: a new tool for the solvent free regioselective C-arylsulfonation of Indoles
No full texttrans-Resveratrol is a natural phenolic component of Vitis vinifera L. (Vitaceae). It has shown a number of biological activities, including protection against coronary heart disease, as a result of different effects: significant antioxidant activity, modulation of lipoprotein metabolism, vasodilatatory and platelet antiaggregatory properties. Recently we have reported the synthesis of a series of resveratrolo-coumarine hybrids that showed interesting vasorelaxant and platelet antiaggregatory activities [1,2].
In an attempt to prepare more active heterocyclic derivatives which incorporate the nucleus of the resveratrol, we synthesised a new series of 2-arylbenzofurane derivatives by an intramolecular Wittig reaction starting from the appropriate triphenylphosphonium salt and the corresponding aroyl chloride. The desired Wittig reagent was readily prepared from the conveniently substituted 2-hydroxy-benzyl alcohol and triphenylphosphine hydrobromide (Figure 1) [3].
However, while developing our methodology, we observed, together with the desired 2-arylbenzofurane derivatives with the general stricture 1, the formation of the side products 2 in a ratio ranging from 2:1 to 8:1.
To get insight on the structure and on the mechanism of formation of these side reaction products, we decided to undertake a mass spectrometric study using an ion trap mass spectrometer operating under both EI and CI conditions. In particularly, MS/MS experiments were performed on the molecular ions and on the diagnostic fragment ions generated by the side products 2 as well as by the side product synthesised from labelled starting aroyl chloride. The data so obtained were consistent with the aroyl-benzofurane structure, a scaffold of many pharmaceutical drug candidates [4], thus allowing us to discover and develop a new and convenient approach to the preparation of this class of active compounds
A New Synthesis of 1,3,5-Triazine with Coumarin Derivatives”e “Synthesis and Immobilization of Some Coumarine Derivatives on a Modified Poly(ethylene glycol
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GAS-PHASE ION/MOLECULE REACTION OF ALFA-VINYL CATION TOWARDS RING-SUBSTITUTED BENZENES IN AN IT-MS
No full textIDENTIFICATION AND STRUCTURAL CHARACTERIZATION OF BY- PRODUCTS IN THE SYNTHESIS OF 2- AND 3-SULFONYLINDOLES BY EI, ESI-HRMS AND TANDEM MASS SPECTROMETRY
No full textIndole skeleton is a widespread motif in many natural products, pharmaceuticals, and fine chemicals. In particular, considerable attention has been focused on 1- and 3-arylsulfonyl-1H-indoles, some of which demonstrated to be valid HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
In an attempt to prepare more potent heterocyclic derivatives which incorporate the indole nucleus, we synthesised a new series of 2- and 3-sulfonylindoles derivatives by ZnO-mediated regioselective C-arylsulfonylation of indoles using aromatic sulfonyl chlorides under solvent free conditions [1].
However, while developing our methodology, we observed, together with the desired sulfonylindoles, the formation of unexpected by-products when sulfonyl chlorides bearing strong electron withdrawing groups were used.
To gain insight into the structure of these unknown compounds and the chemistry of their formation, we decided to undertake first HRMS experiments upon electrospray ionization. Subsequently, in order to achieve more structural information, we performed MSn experiments on the protonated species and on the molecular ion obtained under ESI and EI conditions, respectively. Unexpectedly, we found that the m/z values of the M+. ions observed under EI conditions were shifted, under ESI condition, to m/z 16 higher than expected. These data suggested that these molecules are susceptible to oxidation in positive –ion ESI to form a [M+H+O]+ species.
In this work we report the strategy employed for the unequivocal identification of the unknown by-products together with the general fragmentation scheme useful for the identification of similar derivatives
Gas-phase ion/molecule reaction of alpha-phenylvinyl cation towards ring-substituted benzenes in an IT-MS
No full textGas-phase ion-molecule reaction of alpha-phenylvinyl cation towards substituted benzenes in the enviroment of an ITMS
No full textIon-molecule reactions between the α-phenylvinyl cation (α-PVC) and mono-substituted benzenes have been investigated using a quadrople ion-trap mass spectrometer. The α-PVC, generated by chemical ionization from phenylacetilene, was found to react selectively with mono-substituted benzenes bearing electron withdrawing groups to give the product ions [M + 103](+) and the trans-vinylating product ions [M + 25](+). To characterize the reaction products, a combination of collision-induced dissociation, isotope-labeling experiments and model compounds were used. The results indicate, in addition to direct heteroatom alkylation, high extent of ortho attack. We attributed the positional selectivity of the α-PVC to the nature of the substituent on the neutral molecule. In particular, hydroxy and amino groups promoted the alkenylation at ortho positio
Sintesi di un sale d’ammonio tetrakis – PEG supportato quale nuovo catalizzatore per trasferimento di fase efficace e riciclabile
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