Controlling Selectivity at the First Hydrogenation Level: Synthesis of 3‐Hydroxyisoindolines by Heterogeneously Silver‐Catalyzed Monohydrogenation of Phthalimides

The development of robust nanocatalysts able to mediate important organic transformations with high levels of selectivity constitutes a hot topic in fine-chemistry and catalysis fields. In this context, the rational design of heterogeneous catalysts featuring suitable active sites for obtaining 3-hydroxyisoindolinones by the direct monohydrogenation of highly accessible phthalimides is an attractive approach. This work presents the design and successful catalytic application of a robust and recyclable [Ag/Al₂O₃] nanomaterial capable to promote the synthesis of a wide range of 3-hydroxylactams through the catalytic monohydrogenation of phthalimides with total atom-economy. It is important to remark that this transformation proceeds with full chemoselectivity, exhibiting complete tolerance to the presence of (hetero)aromatic rings and being able to stop the hydrogenation at the first intermediate level. A deep effort concerning material catalyst optimization and characterization study are performed, determining that the optimal [Ag/Al₂O₃] is composed of silver nanoparticles with an overall size of 2.3 nm homogeneously distributed across the alumina matrix. The characterization together with the performance of kinetic/mechanistic investigations allows to propose an intimate contact between accessible Ag⁰ sites and Lewis acidic centers is crucial for the catalyst system to perform the hydrogenative process with complete efficiency.