Catalysis by Organic Solids. Stereoselective Diels−Alder Reactions Promoted by Microporous Molecular Crystals Having an Extensive Hydrogen-Bonded Network

Abstract

Anthracenebisresorcinol derivative 1 as an organic network material shows a novel catalysis in the solid state for the acrolein-cyclohexadiene Diels-Alder reaction. The suggested mechanism involves a catalytic cycle composed of sorption of the reactants in the cavities of polycrystalline host 1, preorganized intracavity reaction, and desorption of the product. The host also promotes stereoselective intracavity reactions for alkyl acrylates and cyclohexadiene but, in this case, not in a catalytic manner. Relevance of the present system as a functional organic analog of zeolites is discussed in light of the kinetics of respective elementary processes and the effects of pulverization of the catalyst thereupon as well as X-ray crystal structures.

Use of different microporous and mesoporous materials as catalyst in the Diels–Alder and retro-Diels–Alder reaction between cyclopentadiene and p-benzoquinoneActivity of Al-, Ti- and Sn-doped silica

“…Moreover, when these materials are used as catalysts, their pore dimensions and topology can also influence product selectivity. It is then not surprising that molecular sieves have been used as catalysts for Diels-Alder reactions (DAR) [7][8][9][10][11][12][13][14]. However in many cases the activity of microporous molecular sieves for DAR can be strongly limited by the diffusion of reactants, and products.…”

Challenges and breakthroughs in recent research on self-assembly

“…Aoyama and coworkers investigated formation and guest inclusion phenomena of porous hydrogen-bonded networks composed of bisresorcinol derivatives [118]. As shown in figure 13, hydroxyl groups in the derivatives can form hydrogen bonds of specific geometry, resulting in inclusion of appropriate guests.…”

“…Aoyama and coworkers demonstrated that an anthracene-bisresorcinol derivative, when used as an organic network material, showed a novel catalysis of the acrolein-cyclohexadiene Diels-Alder reaction in the solid state [123][124][125]. In that reaction, the two reagents have differing polarities and so could be assembled within the same cavity.…”

Nanoporous Catalytic Materials with Organic Frameworks

“…Aoyama and coworkers showed that an H-bonded organic coordination network based on an anthracenebisresorcinol derivative can catalyze Diels-Alder reactions with high rate enhancements and stereoselectivities. [11] A second approach for making nanoporous organic materials involves the use of phase-separated block copolymers. Block copolymers containing blocks that are sufficiently incompatible with each other, often spontaneously form ordered phase-segregated architectures.…”