Abstract 2 (4H)-5, 6-Dihydrobenzofuranones 3 gave, when treated with pyridine hydrochloride at 200, the corresponding arylacetic acids 1 in good yields, whereas the aza analogues, the tetrahydrooxindoles 6 gave indoles in poor yields. The oxidation products of 3 (11 and 13) and of 6 (12, 14 and 15) gave, with the same reagent, benzofuranones and oxindoles, respectively, both in good yields.
