Dependence of reactivity of a novel 2,6-diamino pyridine-based enediyne on the extent of salt formation with external acids: a possible implication in pH based drug design

A novel pyridine diamine-based cyclic enediyne 1 was synthesized by bis-N-alkylation of 2,6-bis-sulfonamido pyridine 6 followed by deprotection with thiophenol. A variety of salts 1a–c of the parent amine 1 were prepared. Thermal reactivity studies indicated a dependence of the reactivity upon the extent of salt formation. This observation may be useful in pH-based design of enediynes.