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 R1COCH2COR2 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