A Metal‐Organic Framework Brønsted Acid Catalyst: Synthesis,Characterization and Application to the Generation of Quinone Methides for [4+2] Cycloadditions
A Brønsted acid‐derived metal‐organic framework (MOF) has been developed to serve as an efficient heterogeneous catalyst for a [4+2] cycloaddition. Aromatic sulfonyl groups were successfully installed using commercially available anhydridic reagents during post‐synthetic modifications. The MIL‐101‐NH‐RSO3H MOF catalyst was fully characterized by SEM, PXRD, FTIR, TGA and N2 adsorption/desorption isotherm. Furthermore, a novel [4+2] cycloaddition of substituted 2‐vinyl‐substituted phenol was evaluated. The MIL‐101‐NH‐RSO3H catalyst showed superior catalytic capabilities when compared to a few other strong homogeneous Brønsted acid catalysts. The MIL‐101‐NH‐RSO3H catalyst is compatible with a variety of substituted substrates and it can be recycled five times without loss of yield or selectivity.
