Synthesis Of Cyclohexenones Via Aldol Reaction Catalyzed By Modified Proline

Cyclohexenones are important fine organic chemical intermediates. Their unsaturatedcyclic structures have high chemical reactivity, which are often used to synthesize complexpolycyclic or heterocyclic compounds. Such as herbicides, substituted phenolintermediates. Currently, there are many methods of synthesis of cyclohexenones, forexample, the oxidation of cyclohexene used cobalt naphtenate as catalyst in an acidicenvironment, two-step oxidation synthesis of the target product used4-vinylcyclohexene asraw materials, etc. But for most of these methods, the reaction process are relativelyrigorous, low yields, more byproducts and relatively more serious pollution problems, suchas the difficulty to separate and to achieve industrialization. Therefore, the research anddevelopment of new synthetic routes provide an important academic significance andapplied value.In the paper, we used aldehyde and acetone as raw materials, modified L-Proline ascatalyst, via aldol condensation reaction and further Robinson cyclization to exploresynthetic cyclohexene ketone compounds. We prepared these small molecule materialsused SiO2NPs and silica gel as carriers. These small molecule materials werecharacterized by SEM, TEM, FTIR, TGA and so on. Then the catalytic properties of thesesmall molecule materials were investigated. The work includes three aspects:(1) In the round bottom flask, N-Boc-L-Proline was connected to300-400nm silicapowder as catalysts. The small molecule materials showed good catalytic activity in thealdol condensation reactions at room temperature without cocatalyst. Furthermore, thecatalyst could be recycled several times without losing catalytic activity.(2) In the silica gel column, N-Boc-L-Proline was connected to300-400nm silicapowder as catalysts. The small molecule materials showed good catalytic activity in thealdol condensation reactions at room temperature without cocatalyst. Furthermore, thecatalyst could be recycled several times without losing catalytic activity. In addition, thecatalytic activity in the silica gel column and round bottom flask were compared.(3) SiO2nanoparticles with350nm in diameter were synthesized. Using SiO2nanoparticles as carrier getting heterogeneous catalysts, an efficient method has been developed for aldol condensation reaction under mild conditions. However, because of theless effective connection of SiO2nanoparticles and L-Proline, the catalytic effect is poor.