Synthesis of 1-tetralones by intramolecular Friedel–Crafts reaction of 4-arylbutyric acids using Lewis acid catalysts

Intramolecular Friedel–Crafts reaction of 4-arylbutyric acids efficiently proceeded in the presence of catalytic amounts of Lewis acids such as Bi(NTf2)3 and M(OTf)3 (M=Bi, Ga, In and rare-earth metals) to form 1-tetralones. Chroman-4-one and thiochroman-4-one were also obtained in good yields from 3-phenoxypropionic acid and 3-phenylthiopropionic acid, respectively.