|Titolo:||IDENTIFICATION AND STRUCTURAL CHARACTERIZATION OF BY- PRODUCTS IN THE SYNTHESIS OF 2- AND 3-SULFONYLINDOLES BY EI, ESI-HRMS AND TANDEM MASS SPECTROMETRY|
|Data di pubblicazione:||2014|
|Abstract:||Indole 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 . 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.|
|Tipologia:||4.2 Abstract in Atti di convegno|
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