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Abstract
The use of strain-promoted azide-alkyne cycloadditions (SPAAC) has become increasingly popular due to its high efficiency and wide applicability. It has been used for probing cell metabolism, analyzing drug uptake, functionalizing material surfaces, among many other applications. SPAAC, as the name implies, requires an azide and a cyclic alkyne. Many of these cyclic alkyne reagents are hydrophobic due to the need for striking a balance between stability and reactivity. This also presents a challenge when attempting to analyze these reactions in aqueous conditions. Here, we report the synthesis, characterization, and kinetic analysis of dibenzocyclooctyne-triazole-EG4-OH (DIBOT): a fast-reacting, water soluble cyclooctyne, and its precursors. The precursor, mono-cyclopropenone caged dibenzocyclooctyne-triazole-EG4-OH (MC-DIBOT) is capable of photo-initiated decarbonylation. Both MC-DIBOT and DIBOT are water soluble which allows us to analyze the reaction kinetics of the SPAAC reaction in aqueous solvents. We also plan to study the affects of water on the rate of the IEDDA reaction between DIBOT and 3,6-bipyridyl-1,2,4,5-tetrazine. We also report on the attempted synthesis of a water soluble bis-cyclopropenone caged dibenzocyclooctadiyne SPAAC reagent (WS-BC-DIBOD). It has been shown that each of the acetylene units of dibenzocyclooctadiyne (DIBOD) undergo the SPAAC reaction at significantly different rates. A compound such a WS-BC-DIBOD would allow for analysis of how the inclusion of water affects the rate of slower SPAAC reactions.