Synthesis and neuroleptic activity of 3-(1-substituted-4-piperidinyl)-1,2-benzisoxazoles

The synthesis of a series of 3-(1-substituted-4-piperidinyl)-1,2-benzisoxazoles is described. The neuroleptic activity of the series was evaluated by utilizing the climbing mice assay and inhibition of [3H]spiroperidol binding. Structure-activity relationships were studied by variation of the substituent on the benzisoxazole ring with concomitant variation of four different 1-piperidinyl substituents. Maximum neuroleptic activity was realized when there was a 6-fluoro substituent on the benzisoxazole ring. The 1-piperidinyl substituent appeared less significant, although in most cases, the (1,3-dihydro-2-oxo-2H-benzimidazol-1-yl)propyl group imparted maximum potency. The most potent compound in both assays was 6-fluoro-3-[1-[3-(1,3-dihydro-2-oxo-2H-benzimidazol-1-yl) propyl]-4-piperidinyl]-1,2-benzisoxazole (11b).