GC/MSn analysis of the crude reaction mixtures from Friedel-Crafts acylation: Unambiguous identification and differentiation of 3-aroylbenzofurans from their 4- and 6-regioisomers.

RATIONALE: 3-Aroylbenzofurans and their 2-nitrophenyl derivatives constitute fundamental intermediates for the synthesis of target compounds with pharmaceutical properties. However, their preparation via the Friedel-Crafts acylation of 2-phenylbenzofurans, using Lewis acid as catalyst, often leads to mixtures of regioisomeric aroylbenzofurans that can be challenging to distinguish, thus preventing the reaction characterization. METHOD: We report a method for the unambiguous identification and differentiation of the desired 3-benzoyl isomers from their 4- and 6-regioisomers in a crude reaction mixture using gas chromatography coupled to multiple-stage mass spectrometric (GC/MSn ) analysis performed in collision-induced dissociation (CID) mode. RESULTS: Upon electron ionization, each set of isomers displayed nearly identical mass spectra. MSn revealed fragmentation patterns that varied in the location of the benzoyl group on the benzofuran scaffold: CID experiments performed on the molecular ion allowed the distinction of the 3-acyl isomers from the 4- and 6-regioisomers; CID experiments on the [M - Ar]+ ion allowed the distinction of the 4-benzoyl from the 6-benzoyl regioisomer, when the nitro group is located on the 2-phenyl ring. Moreover, the unusual loss of OH• radical allowed ascertaining the position of the nitro group in 3-acyl regioisomers bearing the NO2 group. The origin of the diagnostic OH• loss was investigated through MSn experiments using 18 O-labelled 3-benzoyl derivatives. CONCLUSIONS: The method allows the rapid characterization of crude reaction mixtures of benzoylbenzofurans using solely GC/MSn analysis, simplifying the workflow of extensive isolation and purification for structure elucidation.

Potent and Selective Activity against Human Immunodeficiency Virus 1 (HIV-1) of Thymelaea hirsuta Extracts.

Historically, natural products have been the most successful source of inspiration for the development of new drugs. Members of the Thymelaeaceae family have been of interest owing to their excellent medicinal value. Given the successful history of natural product-based drug discovery, extracts from the aerial parts of Thymelaea hirsuta were essvaluated for their potential anti-human immunodeficiency virus type 1 (HIV-1) activity. Ethyl acetate extracts from leaves (71B) and branches (72B) of Thymelaea hirsuta showed potent and selective activity against HIV-1 wt (EC50 = 0.8 µg/mL) at non-cytotoxic concentrations (CC50 > 100 µg/mL). They proved to be active against HIV-1 variants carrying clinically relevant NNRTI and NRTI mutations at low concentration (0.3-4 µg/mL range) and against the M-tropic strain HIV-1 BaL. The 72B extract, chosen as a lead, was not able to inhibit the RT and protease enzymatic functions. Furthermore, it was not virucidal, since exposure of HIV to high concentration did not affect virus infectivity. The pre-clinical safety profile of this extract showed no adverse effect on the growth of Lactobacilli, and non-toxic concentration of the extract did not influence the Caco-2 epithelial cells monolayer integrity. Additionally, extract 72B prevented syncytia formation at low concentration (0.4 µg/mL). The potent inhibitory effect on the syncytia formation in co-cultures showed that 72B inhibits an early event in the replication cycle of HIV. All of these findings prompt us to carry on new studies on Thymelaea hirsuta extracts.

Unexpected detection of 3-aroylbenzofuran side products in the preparation of 2-arylbenzofurans: Identification, characterization, and comparison with chalcone's fragmentation patterns using EI/MSn.

A gas chromatography-mass spectrometry study of the intramolecular Wittig reaction revealed, together with the expected 2-phenylbenzofuran, the formation of an unexpected side product that has not been reported until now. This study reports the identification of the by-product, ie, the 3-benzoyl-2-phenylbenzofuran, on the base of its mass spectrometric behaviour using a combination of electron ionization, exact mass measurement, multiple stage mass spectrometry, and labelled compounds. This study reports the common fragmentation pathways and discusses possible fragment structures of characteristic ions from a series of 3-aroyl-2-arylbenzofuran derivatives obtained as by-product under Wittig conditions. Emphasis is laid on the formation and structure investigation of the [M-H]+ and [M-OH]+ ions. Our results showed interesting analogies with the mass spectrometric behaviour of chalcones.

Conversion of benzoic acid into phenol in an ITMS under CI-MSn conditions. Recognition of ortho-chlorobenzoyl derivatives.

Isomeric chlorobenzoyl cations (m/z 139), under collision-induced experiments, fragment identically. Chlorobenzoyl cations can be efficiently converted into cholorophenol radical cations by the reaction with methanol in the ion trap analyzer under CI-MSn conditions. The substitution of the carbonyl group with a hydroxyl moiety is able to induce an ortho effect, which is absent in the startingortho-chlorobenzoyl cation. This transformation could be useful to recognize ortho-chlorinated benzoyl derivatives without the need of MS spectrum comparison of the whole set of isomers. The method reported in this study could be applicable to biologically active molecules that dissociate to form the chlorobenzoyl cations under CI or CI collision-induced dissociation conditions, such as indomethacin, the degradation products from the insect growth regulator 1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea, and lorazepam.

Solvent-Free Addition of Indole to Aldehydes: Unexpected Synthesis of Novel 1-[1-(1H-Indol-3-yl) Alkyl]-1H-Indoles and Preliminary Evaluation of Their Cytotoxicity in Hepatocarcinoma Cells.

New 1-[1-(1H-indol-3-yl) alkyl]-1H-indoles, surprisingly, have been obtained from the addition of indole to a variety of aldehydes under neat conditions. CaO, present in excess, was fundamental for carrying out the reaction with paraformaldehyde. Under the same reaction conditions, aromatic and heteroaromatic aldehydes afforded only classical bis (indolyl) aryl indoles. In this paper, the role of CaO, together with the regiochemistry and the mechanism of the reaction, are discussed in detail. The effect of some selected 3,3'- and 1,3'-diindolyl methane derivatives on cell proliferation of the hepatoma cell line FaO was also evaluated.

Evaluation of the α-phenylvinyl cation as a chemical ionization reagent for the differentiation of isomeric substituted phenols in an ITMS.

Ion-molecule reactions between the α-phenylvinyl cation and isomeric naturally occurring phenols were investigated using a quadruple ion trap mass spectrometer. The α-phenylvinyl cation m/z 103, generated by chemical ionization from phenylacetylene, reacts with neutral aromatic compounds to form the characteristic species: [M + 103](+) adduct ions and the trans-vinylating product ions [M + 25](+) , which correspond to [M + 103](+) adduct after the loss of benzene. Isomeric differentiation of several ring-substituted phenols was achieved by using collision-induced dissociation of the [M + 103](+) adduct ions. This method also showed to be effective in the differentiation of 4-ethylguaiacol from one of its structural isomers that displays identical EI and EI/MS/MS spectra. The effects of gas-phase alkylation with phenylvinyl cation on the dissociation behavior were examined using mass spectrometry(n) and labeled derivatives. Copyright © 2015 John Wiley & Sons, Ltd.

Mild synthetic approach to novel indole-1-carbinols and preliminary evaluation of their cytotoxicity in hepatocarcinoma cells.

A mild and versatile method for the synthesis of some novel indole-1-carbinols has been developed via one-pot reaction of indoles and paraformaldehyde in the presence of an excess of CaO, MgO, ZnO or TiO(2). The solvent-free reaction provided all the indole derivatives in moderate to good yields and short reaction times. Moreover, the effect of some selected indole-1-carbinols on cell proliferation of the hepatoma cell line FaO was evaluated.

Gas-phase ion-molecule reaction of alpha-phenylvinyl cation towards substituted benzenes in the environment of an ITMS.

Ion-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 position.

Formation of 2-substituted benzofuran fragment ions from 6-alkyl- and 6-aryldibenzo(d,f)(1,3)dioxepine derivatives under electron ionization-a useful precursor ion for isomeric differentiation.

Tandem mass spectrometry has been applied to differentiate three sets of o-, m- and p-methyl, -methoxy and -nitro-substituted-6-phenyl-dibenzo(d,f)(1,3)dioxepines. Collision-induced dissociation (CID) experiments have been carried out on 2-phenylbenzo[b]furan fragment ions, which originate from the decomposition of the molecular ions after their EI-induced isomerization to spirocyclic structures. With the exception of m- and p-methylphenylbenzo[b]furan isomers, which display identical CID mass spectra, the three isomeric methoxy- and nitrophenylbenzo[b]furan fragment ions display very characteristic CID behavior which allows unequivocal differentiation of the 6-phenyl-dibenzo(d,f)(1,3)dioxepine isomers. 6-(o-nitrophenyl)-dibenzo(d,f)(1,3)dioxepine isomer, does not form a 2-(o-nitrophenyl)benzo[b]furan ion and, therefore, it can be differentiated from the m- and p- isomers based on the mere EI mass spectra. Furthermore, it shows a characteristic ion most likely due to an ortho effect between the nitro group and the dioxepine ring. Multiple stage mass spectrometric techniques (MSn), labeled derivatives and reference compounds were used in order to gain additional information on the structures of product ion from the CID fragmentation.

PEG-immobilization of cardol and soluble polymer-supported synthesis of some cardol-coumarin derivatives: preliminary evaluation of their inhibitory activity on mushroom tyrosinase.

In this work, the PEG-immobilization and the liquid phase synthesis of some coumarins derived from cardol are presented. Some preliminary results on their tyrosinase inhibitory activity are also included.

2-substituted benzofuran fragment ion formation in the electron ionization mass spectra of 6-alkyl- and 6-aryldibenzo(d,f)(1,3)dioxepine derivatives. 1. Spirocyclization of the molecular ions in the gas phase.

The formation of 2-substituted benzo[b]furan ions in the electron ionization (EI) mass spectra of a series of 6-alkyl- and 6-aryldibenzo(d,f)(1,3)dioxepines has been studied by means of exact mass measurements and multiple-stage mass spectrometry conditions using an ion trap mass spectrometer. The proposed mechanism of formation of benzo[b]furan ions requires the formation of a spirocyclic cyclohexadienone system, which undergoes elimination of a cyclopentadienone molecule. A parallel with the chemical conversion of arylmethyl-substituted dibenzo(d,f)(1,3)dioxepines into an analogous spirocyclic system was also underlined.

Electron ionization-induced fragmentation of some new dibenzo(d, f)(1,3)dioxepine derivatives.

The mass spectrometric behaviour of a series of 6,6-disubstituted dibenzo(d,f)(1,3)dioxepine derivatives have been studied. The fragmentation patterns were described and discussed in detail with the aid of labelled compounds, accurate mass measurements and collisionally induced dissociation experiments performed using an ion trap.

Characterisation of new pyridazinofurocoumarins by electron ionisation and multiple stage tandem mass spectrometry using an ion trap mass spectrometer.

The inverse electron-demand Diels-Alder reaction between furocoumarinones and 3,6-bis(methoxycarbonyl)-1,2,4,5-tetrazine was used to give pyridazinofurocoumarins in good yields. The structural characterisation of the synthesised compounds was achieved by NMR spectroscopy. The mass spectrometric behaviour was studied under electron ionisation conditions via sequential product ion fragmentation experiments (MS(n)). This study allowed the evaluation of the role played by the methyl substituent on the benzene ring of pyridazinofurocoumarins in their fragmentation pathways.

Electron and electrospray ionization mass spectrometry in the characterization of some 1-allyl-3-phenylaziridines.

A series of cis- and trans-isomeric aziridines has been studied under electron impact (EI) and electrospray ionization (ESI) conditions. The fragmentation patterns of the examined compounds have been elucidated by means of sequential product ion fragmentation experiments (MS(n)) performed using an ion trap mass spectrometer. Particular attention has been paid to isomer characterization in these precursors of azetidinones, that in turn are precursors of new beta-lactam antibiotics.

Headspace solid-phase microextraction gas chromatography/mass spectrometry in the analysis of the aroma constituents of 'Cannonau of Jerzu' wine.

"Cannonau of Jerzu" wine is a typical Sardinian product, obtained from only one particular grape variety. Its aroma profile is highly characteristic from the organoleptic point of view but, until now, no analytical investigation of the aroma components has been reported. This aspect has been studied by headspace solid-phase microextraction coupled with gas chromatography/mass spectrometry (GC/MS). Using this approach, 76 abundant aroma components were identified. The results thus obtained show on one hand that the terpene profile is, as expected, dependent on the quality of the grapes (in terms of selection before vintage), and, on the other, that some components are strongly dependent on the production and ageing method.