Design of fluorinated 5-HT4R antagonists: Influence of the basicity and lipophilicity toward the 5-HT4R binding affinities

Synthesis of Fluorinated Amide Derivatives via a Radical N-Perfluoroalkylation-Defluorination Pathway

A one-pot approach to fluorinated hydroxamic acid, amide, and thioamide derivatives is reported. The reaction proceeds via an N-perfluoroalkylation of nitrosoarenes with perfluoroalkanesulfinates, resulting in labile N-perfluoroalkylated hydroxylamines. By the addition of suitable additives, a controllable oxy/thiodefluorination of the fluorinated hydroxylamine intermediates was achieved. The method highlights N-perfluoroalkylated amines as versatile intermediates for further synthesis.

Lowering the pKa of a bisimidazoline lead with halogen atoms results in improved activity and selectivity against Trypanosoma brucei in vitro

Diphenyl-based bis(2-iminoimidazolidines) are promising antiprotozoal agents that are curative in mouse models of stage 1 trypanosomiasis but devoid of activity in the late-stage disease, possibly due to poor brain penetration caused by their dicationic nature. We present here a strategy consisting in reducing the pKa of the basic 2-iminoimidazolidine groups though the introduction of chlorophenyl, fluorophenyl and pyridyl ring in the structure of the trypanocidal lead 4-(imidazolidin-2-ylideneamino)-N-(4-(imidazolidin-2-ylideneamino)phenyl)benzamide (1). The new compounds showed reduced pKa values (in the range 1-3 pKa units) for the imidazolidine group linked to the substituted phenyl ring. In vitro activities (EC50) against wild type and resistant strains of T. b. brucei (s427 and B48, respectively) were in the submicromolar range with four compounds being more active and selective than 1 (SI > 340). In particular, the two most potent compounds (3b and 5a) acted approximately 6-times faster than 1 to kill trypanosomes in vitro. No cross-resistance with the diamidine and melaminophenyl class of trypanocides was observed indicating that these compounds represent interesting leads for further in vivo studies.