Mannich heterogeneous catalysis

Dong et al. reported the preparation of a novel Brbnsted acid-surfactant-combined halogen-free ionic liquid [DDPA][HSO ] that bears a propane sulfonic acid group in an acyclic dimethyldodecylammonium cation (Fig. 12.69) [42] and its use in the heterogeneous catalysis procedure of one-pot three-component Mannich-type reaction in aqueous media. 

Keywords Substituted amines, amines, a,p-unsaturated alkenes, ZrOCla-SHaO/montmorillon-ite KIO, heterogeneous catalysis, solvent-free, room temperature, Mannich reaction, Michael addition... 

Another approach undertaken by Lin and co-workers towards heterogeneous catalysis involved doping metal-organic frameworks (MOFs) with the metal complex chromophores (Figure 10.3). The authors incorporated Ru and Ir complexes U.2L and H2L , respectively, into porous Zr604(0H)4(bpdc)s (bpdc =para-biphenyldicarbo)ylic acid) frameworks to produce MOF-1 and MOF-2, respectively, which were used in nitro-Mannich reactions of THIQ derivatives (Scheme 10.16). Conversions were generally lower for MOF-1 and MOF-2 than for cross-linked polymers or their monomeric counterparts however, these catalysts could be readily filtered off and re-used for subsequent reactions. For example, N-phenyl THIQ was subjected three times to the photocatalyzed nitro-Mannich reaction in the presence of MOF-2, which provided consistent conversions (57-59%) for each run. 

LLC networks containing catalytic headgroups have also been shown to be useful for heterogeneous Lewis acid catalysis. The Sc(III)-exchanged cross-linked Hu phase of a taper-shaped sulfonate-functionalized LLC monomer has been shown to be able to catalyze the Mukaiyama aldol and Mannich reactions [115] with enhanced diastereoselectivity. This Sc(III)-functionalized Hu network affords condensation products with syn-to-anti diastereoselectivity ratios of 2-to-l, whereas Sc(III) catalysts in solution or supported on amorphous polymers show no reaction diastereoselectivity at all. 

---

See also in sourсe #XX -- [ ]

---