Benzo[b]thiophene derivatives. XX. The sulfur isostere of 5,6-Dihydroxytryptamine†

3β-Aminoethyl-5,6-dihydroxybenzo[b]thiophene, the sulfur bioisostere of 5,6-dihydroxytryptamine, a selective neurotoxin, has been synthesized and shown to have significant effect on biogenic amine levels both centrally and peripherally. A derivative, 3β-aminoethyl-5,6-isopropylidenedioxybenzo[b]thiophene, showed significant but opposite activity. The syntheses and preliminary pharmacology are reported.