One-pot synthesis of benzopyran-4-ones with cancer preventive and therapeutic potential

A one-pot synthesis of novel benzopyran-4-ones is described. In a tandem reaction, organobase-catalysed Michael addition of R1 COCH2COR2 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 R1 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 μM). 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 μM, whereas normal peripheral blood mononuclear cells were not affected.