Supramolecular Protection of Carboxylic Acids via Hydrogen Bonding: Selectivity, Reversibility, and Design Principles.

A supramolecular protecting group (sPG) was developed that can selectively protect dicarboxylic acids, enabling the preferential esterification of monocarboxylic acids. The high selectivity (selectivity factor s = 72) was achieved through reversible hydrogen bonding and measured under synthetically relevant conditions. This strategy offers an efficient and dynamic alternative to traditional covalent protecting groups. To deepen understanding and optimize the performance of the supramolecular approach, a systems chemistry model was developed, which was validated by the good agreement with experimental results. The computational model was then used to explore parameter space and define selectivity-limiting factors. The insights gained from the model guided the optimization of reaction conditions and provided general principles for using supramolecular protecting groups (sPGs). This strategy is expected to have broad implications for the development of new synthetic tools for efficient and selective organic chemical transformations in the selective functionalization of complex molecules.