Compartmentalization of Multiple Catalysts into Outer and Inner Shells of Hollow Mesoporous Nanospheres for Heterogeneous Multi-Catalyzed/Multi-Component Asymmetric Organocascade

Abstract

Heterogenization of multicatalyzed cascade/ tandem reactions often suffers from the detrimental interactions of incompatible catalysts. Herein, double-shelled hollow mesoporous nanospheres with isolated sites of ProTMS/-CO 2 H in the outer shell and QNNH 2 /-SO 3 H or QDNH 2 /-SO 3 H in the inner shell were fabricated as highly stereoselective catalysts in heterogeneous Michael addition/αamination organocascade reactions. The spatial compartmentalization, evidenced by TEM-EDS elemental mapping, effectively suppressed the detrimental interaction of QNNH 2 , QDNH 2 , and −SO 3 H with ProTMS/-CO 2 H in the first-step Michael addition. The hollow interior, mesoporous shell, and thin shell thickness facilitated the mass transfer of intermediates into the inner shell where α-amination occurred.

Controlling Heterogeneous Catalysis with Organic Monolayers on Metal Oxides

“…Finally, further optimization of the ability to fine-tune the tail chemistry of organic monolayers and to localize monolayers to specific regions of space on catalyst structures will provide opportunities for preparing compartmentalized catalysts for cascade reactions or for optimization of the catalyst active site environment. , As discussed above, organic functionalization can be used to control the phase to which a catalyst segregates. This can potentially be employed to segregate incompatible catalyst functions for “one-pot” cascade reactions into separate phases.…”

Kinetics Driven by Hollow Nanoreactors: An Opportunity for Controllable Catalysis

“…Reproduced with permission from Ref. [9b] Copyright 2019, American Chemical Society. n) Design of magnetic‐plasmonic multimodular nanoreactor.…”

Compartmentalization and Photoregulating Pathways for Incompatible Tandem Catalysis

“…Scientists have developed multicompartmental catalytic systems based on various strategies including the use of sol–gels, Pickering emulsion droplets, supramolecular metal complex architectures, , and polymers. , Catalytic frameworks fabricated from these materials have realized compartmentalization for multiple active catalytic sites, as epitomized by the cell, and enabled multistep nonorthogonal transformations. − ,− Incorporating responsive elements into the support structures has rendered them “smart”, i.e., allowing for reversible alterations of the physical and chemical properties in response to external stimuli such as temperature, , pH, light, , or enzymes. , The properties of the resulting smart materials impart an additional bioinspired control over single-step catalytic transformations. ,− Manipulation of multicatalytic tandem sequences, however, remains challenging and restricted to the regulation of reactivities via temperature actuation. , This limitation significantly affects the choice of catalysts and limits the feasibility of performing one-pot tandem catalysis at arbitrary temperature ranges. To date, no “smart” catalytic system can use or control different switchable states to tune and activate a desired synthetic pathway among many possible ones during a multistep synthesis.…”