1, 2, 3-Triazabutadiene. XIV. Untersuchungen zur sauren Spaltung Z-E-isomerer 1-Aryl-3-[3-methylbenzthiazolinyliden-(2)]- und 1-Aryl-3-[1,3-dimethylbenzimidazolinyliden-(2)]-triazene

Protecting Triazabutadienes To Afford Acid Resistance

Recent work on triazabutadienes has shown that they have the ability to release aryl diazonium ions under exceptionally mild acidic conditions. There are instances that require that this release be prevented or minimized. Accordingly, a base-labile protection strategy for the triazabutadiene is presented. It affords enhanced synthetic and practical utility of the triazabutadiene. The effects of steric and electronic factors in the rate of removal are discussed, and the triazabutadiene protection is shown to be compatible with the traditional acid-labile protection strategy used in solid phase peptide synthesis.

A Photobasic Functional Group

Controlling chemical reactivity using light is a longstanding practice within organic chemistry, yet little has been done to modulate the basicity of compounds. Reported herein is a triazabutadiene that is rendered basic upon photoisomerization. The pH of an aqueous solution containing the water-soluble triazabutadiene can be adjusted with 350 nm light. Upon synthesizing a triazabutadiene that is soluble in aprotic organic solvents, we noted a similar light-induced change in basicity. As a proof of concept we took this photobase and used it to catalyze a condensation reaction.

Water-soluble triazabutadienes that release diazonium species upon protonation under physiologically relevant conditions

Triazabutadienes are an understudied structural motif that have remarkable reactivity once rendered water-soluble. It is shown that these molecules readily release diazonium species in a pH-dependent manner in a series of buffer solutions with pH ranges similar to those found in cells. Upon further development, we expect that this process will be well suited to cargo-release strategies and organelle-specific bioconjugation reactions. These compounds offer one of the mildest ways of generating diazonium species in aqueous solutions.