Stability, Kinetic, and Mechanistic Investigation of 1,8-Self-Immolative Cinnamyl Ether Spacers for Controlled Release of Phenols and Generation of Resonance and Inductively Stabilized Methides

Abstract

Three cinnamyl ether spacers (non-methyl, α-methyl, and γ-methyl) for caging of phenols have been synthesized and are physiologically stable. When triggered, the γ-methyl spacer releases phenols (pKa 7.8 and 9.8) with a t1/2 < 30 s and <2 min in aqueous and aqueous-organic solvent, respectively. The α-methyl spacer releases a phenol (pKa 7.8) with a t1/2 = 27 and 54 min. For the γ-methyl spacer, the results suggest the presence of a resonance and inductively stabilized aza-cinnamyl methide.