6-Hydroxy-4-[2-(di-n-propylamino)ethyl]indole: synthesis and dopaminergic actions

The title compound was proposed to be a biologically active metabolite of a dopaminergic agent, 4-[2-(di-n-propylamino)ethyl]indole. This proposed metabolite was synthesized by a multistep sequence beginning with methyl 3,5-dinitro o-toluate, and involving the Batcho-Leimgruber modification of the Reissert indole synthesis. The target compound exhibited high potency/activity in vivo in a cat cardioaccelerator nerve assay and in vitro in an isolated cat atrium assay. It manifested maximal pharmacological effect less than 5 min after intravenous administration in cats, as compared with a 20-min lag time following intravenous administration of the nonoxygenated congener. These pharmacological data are consistent with the proposal that the target compound is a metabolite of 4-[2-(di-n-propylamino)ethyl]indole.