Monoethyl Pimelate

Monoethyl Pimelate is a versatile, aliphatic dicarboxylate-derived linker building block designed to support PROTAC assembly by providing controlled spacing and multiple functional handles for conjugation. Its esterified carboxylate functionality can be leveraged to tune linker polarity and reactivity, facilitating stepwise synthesis of target-binding and E3-ligase-binding modules. The molecule will be described in detail below, with emphasis on structural features and practical PROTAC-relevant coupling considerations.

Structure: Monoethyl Pimelate is an esterified pimelic acid derivative featuring a flexible aliphatic chain bearing two carboxylate functionalities, one as an ethyl ester and one as a carboxylic acid. It contains ester and carboxylic acid functional groups capable of hydrogen bonding and forming stable amide or ester linkages.

Reactivity: For PROTAC construction, this linker is typically used in coupling strategies that convert the carboxylic acid into activated intermediates (such as acid chlorides or activated esters) before nucleophilic substitution with amine-bearing partners to form amide bonds. Alternatively, ester hydrolysis can generate a free acid for subsequent activation. Common conditions employ inert atmospheres, dehydrating coupling reagents, and polar aprotic solvents to promote efficient condensation while minimizing side reactions.