A series of methyl 2-arylthio-(2) and 2-aryloxy-acetoacetates (3) have been prepared and their tautomeric equilibria have been examined by 1H NMR spectroscopy. S-substitution at the α-position results in an increase of enol tautomer over 90%, while the O-analogues exist predominantly in the keto form (Table 1). Pyrex-filtered irradiation of 2-arylthio compounds 2a-1 in benzene-methanol (1: 1) solution gives benzothiophene derivatives (6a–f, 7–10) ...
