H. Hall

Potential antipsychotic agents. 6. Synthesis and antidopaminergic properties of substituted N-(1-benzyl-4-piperidinyl)salicylamides and related compounds. QSAR based design of more active members

A number of substituted 2-methoxybenzamides, with and without 6-hydroxy groups, with 4-piperidinyl side-chains have been synthesized and evaluated for their antidopaminergic properties. The salicylamides were found to require a lipophilic N-substituent, like a benzyl group, for high affinity for the dopamine D-2 binding site in contrast to salicylamides with 2-pyrrolidinylmethyl side-chains. Furthermore, the influence of the aromatic substituents on the activity in the 2 series, ie 4-piperidinyl and 2-pyrrolidinylmethyl side-chains, was different. This was supported by a Hansch analysis, which could accomodate both phenolic and non-phenolic benzamides with 1-benzyl-4-piperidinyl side-chains. The activity is primarily dictated by electronic features rather than by steric and lipophilic properties. The QSAR equations were validated by the design and synthesis of a new 10-fold more active derivative. The 2 classes of benzamides with different side-chains are suggested to act on different binding sites or on different subtypes of the dopamine D-2 receptor.