Enamines heterogeneous catalysis

We have shown that heterogeneous catalysis can be applied to reductive alkylation with success in reactions such as ether synthesis or N-alkylation of amides and anilines. Concerning the mechanism, several pathways are in competition depending on the structure of the substrate and of the alkylating agent. The important point is that both the product of addition (the hemiacetal or hemiaminal) and the product of elimination (imine, enamine or enolether)... 

The heterogeneous catalysis process requires the formulation of a multifunctional catalyst which at a first approximation presents (i) acidic properties (amine adsorption, dehydration,...) and (ii) a hydro-dehydrogenating function (methanol dehydrogenation, hydrogenation of imine and enamine intermediates). 

Sonochemical activation can strongly improve a wide range of chemical transformations however, the influence of ultrasound on asymmetric organocatalytic reactions is still a very weakly explored area. Based on reported ejamples it could be a very attractive and useful technique for accelerating organocatalytic reactions in heterogeneous systems (e.g., phase-transfer catalysis or reaction with sohd substrates on water). Evaluation of the usefidness of ultrasound in homogenous systems (e.g., in enamine activation) is still difficult and this topic requires more systematic studies in the future. 

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