N-(6-Aminohexyl)maleimide trifluoroacetate salt

N-(6-Aminohexyl)maleimide trifluoroacetate salt, is a maleimide-functional reagent designed to enable efficient conjugation in PROTAC assembly workflows. Its maleimide motif supports selective coupling to thiol-bearing ligands, while the aminohexyl spacer provides flexible spatial separation to tune effective degrader geometry. The trifluoroacetate counterion enhances handling and solubility, facilitating reproducible linker incorporation. Detailed structural and reactivity considerations are provided below.

Structure: The molecule contains a maleimide ring conjugated to an aminohexyl side chain, providing a nucleophile-reactive electrophilic alkene within the maleimide. It is present as a trifluoroacetate salt, with ionic association improving formulation. The structure features amide functionality and a flexible aliphatic spacer.

Reactivity: Maleimide groups typically undergo thiol–maleimide addition under mild, aqueous or mixed-solvent conditions, following a Michael-type addition mechanism to form a stable thioether adduct. For PROTAC construction, thiol-containing warheads or intermediate conjugates are reacted with this linker while maintaining pH conditions that favor thiolate formation without promoting maleimide hydrolysis. Commonly used solvents include buffered aqueous media or polar organic mixtures; catalysts are generally not required, but oxygen exposure and competing nucleophiles should be minimized.