Benzo[b]thiophene derivatives I. 6-methoxybenzo[b]thiophene analogs of plant growth regulators

The acid catalyzed ring closure of an appropriately substituted phenyl ketoester sulfide served as the initial reaction in the synthesis of several 3,4- and 3,6-disubstituted benzob]thiophenes. One of these compounds, 4-methoxybenzob]thienyl-3-acetic acid, showed marked plant growth enhancement.