NONPEPTIDE HIV PROTEASE INHIBITORS - DIFFERENTIAL INTRODUCTION OF ALKYLAMINO GROUPS INTO THE 2 ARYL RINGS OF HALOPERIDOL

In efforts to synthesize haloperidol analogues with improved propertie s as HIV protease inhibitors, methods were sought to introduce mono- a nd dialkylamino groups into the two aromatic rings of the parent struc ture. We report here that the reaction of haloperidol with alkylamines in the presence of a strong base (NaNH2) regiospecifically introduces the alkylamino group into the chlorophenyl ring, whereas the same rea ction in the presence of a weak base (K2CO3) results in exclusive repl acement of the fluorine of the fluorophenyl ring. Different amine func tions can be introduced at the two rings by sequential reactions in th e presence of, respectively, a strong and a weak base. The reaction ca talyzed by NaNH2 involves, at least in part, benzyne formation, wherea s the reaction catalyzed by K2CO3 involves direct nucleophilic additio n to the aromatic ring. The regiospecificity of the reaction is due to conjugation of the fluorophenyl ring to a ketone group. The fluorophe nyl ring is activated by the ketone towards nucleophilic aromatic subs titution but is deactivated by the same function when it is converted by strong base to the enolate anion. Carbonyl conjugation of one of tw o haloaryl groups appears to be a general strategy for regiospecific i ntroduction of alkylamino functions into complex aromatic molecules. T he alkylamino derivatives actually prepared are comparable to haloperi dol as inhibitors of the HIV-1 protease.