An efficient and convenient synthesis of furocoumarins via Pechmann reaction on ZnCl2/Al2O3 under microwave irradiation
Furocoumarins were rapidly synthesized via Pechmann condensation of 6-hydroxybenzofurans with ethylacetoacetate catalyzed by ZnCl2/Al2O3 under solvent-free condition.
Synthesis and photooxygenation of linear and angular furocoumarin derivatives as a hydroxyl radical source: Psoralen, pseudopsoralen, isopseudopsoralen, and allopsoralen
Synthesis of linear and angular furocoumarins with new skeleton structure of potential photobiological feature interest was carried out through Williamson reaction of hydroxycoumarins with 3-chloro-2-butanone followed by cyclization with polyphosphoric acid or by heating in a strongly alkaline solution. The photooxygenation reactions of synthesized furocoumarins were performed in chloroform and in the presence of tetraphenylporphyrin as singlet oxygen sensitizer (1O2). The photooxygenation reactions afforded the photocleaved product through [2 + 2] cycloaddition and the photooxygenated products through ene reaction and [4 + 2] cycloaddition. The photoproducts were isolated and fully characterized by spectral analyses.