Synthetic routes to 2-(2-benzofuranyl)benzoic acids and their cyclization into benz[6]indeno[2,1-d]furan-10-ones

The benz[6]indeno[2,1-d]furan-10-ones 1 were prepared by the intramolecular cyclization of the 2-(2-benzofuranyl)benzoic acids, 2, the unequivocal routes to which are described herein. Various synthetic methods to these acids were tested, as well as the methods to cyclize them.