RESUMO
The flavin mononucleotide (FMN) riboswitch is an emerging target for the development of novel RNA-targeting antibiotics. We previously discovered an FMN derivative, 5FDQD, that protects mice against diarrhea-causing Clostridium difficile bacteria. Here, we present the structure-based drug design strategy that led to the discovery of this fluoro-phenyl derivative with antibacterial properties. This approach involved the following stages: (1) structural analysis of all available free and bound FMN riboswitch structures; (2) design, synthesis, and purification of derivatives; (3) in vitro testing for productive binding using two chemical probing methods; (4) in vitro transcription termination assays; and (5) resolution of the crystal structures of the FMN riboswitch in complex with the most mature candidates. In the process, we delineated principles for productive binding to this riboswitch, thereby demonstrating the effectiveness of a coordinated structure-guided approach to designing drugs against RNA.
Assuntos
Antibacterianos/farmacologia , Mononucleotídeo de Flavina/farmacologia , Quinoxalinas/farmacologia , RNA Bacteriano/antagonistas & inibidores , Riboswitch , Antibacterianos/síntese química , Antibacterianos/química , Bactérias/efeitos dos fármacos , Sequência de Bases , Sítios de Ligação , Desenho de Fármacos , Mononucleotídeo de Flavina/síntese química , Mononucleotídeo de Flavina/química , Ligantes , Estrutura Molecular , Quinoxalinas/síntese química , Quinoxalinas/química , RNA Bacteriano/genética , Relação Estrutura-AtividadeRESUMO
Addition of tributylstannylmetallics to (R)-tert-butanesulfonimine derivatives of arylaldehydes provides alpha-sulfinamidostannanes with high (>98% de) diastereoselectivities. Oxidation of these compounds with m-CPBA gives alpha-sulfonamidostannanes which undergo Pd/Cu-catalyzed Stille-type couplings with benzoyl chloride. Best yields are achieved using the electron-rich tris(2,4,6-trimethoxyphenyl)phosphine as the ligand. Inversion of configuration at the benzylic carbon is observed.
RESUMO
[reaction: see text]. Addition of Bu3SnLi to tert-butanesulfinimines proceeds with high diastereoselectivities to provide the expected adducts in excellent yields and typically with dr = >99:1. These adducts are readily converted to enantiomerically enriched N-Boc-protected alpha-aminoorganostannanes with complete retention of configuration.
