One‐Pot Synthesis of Benzopyran‐4‐ones with Cancer Preventive and Therapeutic Potential

Abstract A one‐pot synthesis of novel benzopyran‐4‐ones is described. In a tandem reaction, organobase‐catalysed Michael addition of R 1 COCH 2 COR 2 on chromone‐3‐carboxylic acid led to decarboxylation and pyran‐4‐one ring opening of the latter. This was followed by chromone‐ and/or chromanone ring closure of the resulting Michael adducts when R 1 is an ortho ‐hydroxyaryl group. Antioxidant testing of 14 derivatives identified strong antiradical properties of chromanones 3o – r (2.1–3.1 µmol Trolox equiv./µmol compound in the DPPH assay). Chromanones 3p and 3r and 2‐styrylchromone 3k were also most potent in inducing the cytoprotective Keap1‐Nrf2 signalling pathway in a reporter gene assay (fivefold induction at concentrations <3 µ M ). Of the seven compounds evaluated for antiproliferative activities, 3k and 3r were the most active, inhibiting leukaemia K562 cell proliferation by 50 % after 72 h at concentrations of 4.5 and 7.9 µ M , whereas normal peripheral blood mononuclear cells were not affected.