Isoxazole derivatives as centrally acting muscle relaxants. I Synthesis and activity of 5-(3-aminopropyl)amino-3-phenylisoxazole derivatives

A series of 5-amino-3-phenylisoxazole derivatives was synthesized and evaluated as part of a search for new types of centrally acting muscle relaxants. The derivtives with an alkylaminopropyl moiety exhibited muscle relaxant activity comparable to that of tolperisone (1), but this activity was accompanied by strong general central nervous system (CNS) depressant and slight anticonvulsant activities.On the other hand, the derivative with a propanamide moiety exhibited a favorable pharmacological profile for a selective muscle relaxant with little CNS depressant action.