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Synthesis of novel derivatives of 4-amino-3,5-dicyanopyrazole
Campos, Ana M. F. Oliveira; Gonçalves, M. Sameiro T.; Rodrigues, Lígia M.; Proença, M. Fernanda R. P.; Griffiths, John; Maia, Hernâni L. S.Diazotisation of substituted arylamines followed by reaction with malononitrile gave substituted arylazomalononitriles. Cyclisation of these intermediates with chloroacetonitrile and triethylamine, as base, gave the corresponding new aminodicyanopyrazoles, in 22–80% yields.
Fries rearrangement of dibenzofuran-2-yl ethanoate under photochemical and Lewi...
Campos, Ana M. F. Oliveira; Oliveira, Ana M. A. G.; Raposo, M. Manuela M.; Griffiths, John; Machado, António E. H.The Fries rearrangement of dibenzofuran-2-yl ethanoate as a route to o-hydroxyacetyldibenzofurans has been investigated, both under thermal Lewis-acid catalysed and non-catalysed photochemical conditions. The reactions were examined theoretically at semi-empirical (PM3 and ZINDO/S) and density functional theory (DFT) levels. The correct selection of reaction conditions provides viable preparative routes to orth...
Synthesis of psoralen analogues based on dibenzofuran
Campos, Ana M. F. Oliveira; Oliveira, Ana M. A. G.; Raposo, M. Manuela M.; Griffiths, John; Machado, António E. H.The syntheses of four novel psoralen derivatives, 6a-d, of the benzofurocoumarin (=benzofuro[1]benzopyranone) type containing an ester group are described. These compounds might be of interest in PUVA (psoralen long-wave ultraviolet radiation) therapy. The overall efficiency of the synthetic procedure is greatly limited by the low yields for the penultimate step, i.e. formylation of the dibenzofuranols 3a,c or ...
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