Geminal dialkyl derivatives of N-substituted pantothenamides: synthesis and antibacterial activity

As a key precursor of coenzyme A (CoA) biosynthesis, pantothenic acid has proven to be a useful backbone to elaborate probes of this biosynthetic pathway, study CoA-utilizing systems, and design molecules with antimicrobial activity. The increasing prevalence of bacterial strains resistant to one or more antibiotics has prompted a renewed interest for molecules with a novel mode of antibacterial action such as N-substituted pantothenamides. Although numerous derivatives have been reported, most are varied at the terminal N-substituent, and fewer at the β-alanine moiety. Modifications at the pantoyl portion are limited to the addition of an ω-methyl group. We report a synthetic route to N-substituted pantothenamides with various alkyl substituents replacing the geminal dimethyl groups. Our methodology is also applicable to the synthesis of pantothenic acid, pantetheine and CoA derivatives. Here a small library of new N-substituted pantothenamides was synthesized. Most of these compounds display antibacterial activity against sensitive and resistant Staphylococcus aureus. Interestingly, replacement of the ProR methyl with an allyl group yielded a new N-substituted pantothenamide which is amongst the most potent reported so far.