A divergent synthesis of minor groove binders with tail group variation

A new synthesis of polyamide minor groove binders in which diversity is introduced by the nucleophilic substitution of a 2-sulfido-1,3,2-diazaphospholidinyloxy substituent by volatile secondary amine nucleophiles is described. Such a method has potential value for economically investigating structure-activity relationships in this important class of compounds through library synthesis. As an example using this method are prepared two new minor groove binders with pyrrolidinyl or piperidinyl tail groups that are close relatives of highly active antibacterial minor groove binders with morpholinyl tail groups. The antibacterial activity found against Staphylococcus aureus and Mycobacterium spp. indicates that the pK(a) of this set of compounds is not the dominant factor in determining the antibacterial activity.