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 front 3-phenoxypropionic acid and 3-phenylthiopropionic acid, respectively. (C) 2003 Elsevier Science Ltd. All rights reserved.