Iron(II) promoted direct synthesis of dibenzo[b,e]oxepin-11(6H)-one derivatives with biological activity. A short synthesis of doxepin

A novel and efficient synthesis of dibenzob,e]oxepin-11(6H)-ones by direct intramolecular ortho-acylation from readily available 2-(phenoxymethyl)benzoic acids was developed. The method takes advantage of a newly developed cooperative system consisting of sustainable FeCl₂ and Cl₂CHOCH₃ as the key components. This methodology is compatible with a wide variety of functional groups in good to excellent yields and high regioselectivity. The synthetic application of new protocol was extended to the synthesis of known tricyclic drug doxepin as well as a small library of oxepin based derivatives. For the first time, the obtained dibenzob,e]oxepinone derivatives were evaluated for their biological activities on the free-living nematode Caenorhabditis elegans as an effective and cost-efficient model system for anthelmintic discovery.