3-Amino-N-aryl-2-hydroxypropane-1-sulfonamides were synthesized by the reaction of the corresponding epoxy sulfonamide with sodium azide, followed by reduction to the corresponding amine. The synthesis of 3-nitropropan-1-amine and two 2-thienyl derivatives is also reported. 3-Amino-2-hydroxy-N-(4-nitrophenyl)propane-1-sulfonamide and 3-nitropropan-1-amine were found to be specific antagonists of GABA at the GABAB receptor. Substitution of the amino group by alkyl or aryl groups reduced the activity.