Synthesis Of New Organocatalysis And The Catalytic Knoevenagel Condensation

Knoevenagel condensation is a common and powerful synthetic method for formingcarbon-carbon bonds in organic synthesis, which is also the typical of modern organiccatalytic reaction, and it has a long history of research and industrial applications. Howeverunexpectedly, the research on asymmetric catalytic Knoevenagel reaction is seldom reported.This paper construct a variety of new asymmetric organocatalysis by cheap and simplematerials, which are used in the Knoevenagel condensation as follows.In Chapter2, a simple way to prepare urea compounds derived from L-amino acids wasput forward. By this method the urea derivatives was synthesized through three-stepreaction. We had prepared an ester-protection of amino acid and isocyanate group viasuccessively modifying the two functional groups of L-phenylalanine, to synthesize ureaderivatives based on amino acid scaffold. The structures of the products were confirmed by1HNMR, MS and X-ray analysis.In Chapter3, we screened a highly active amino-urine compounds catalyst withdaul-functional catalytic groups. The organocatalyst could effectively catalyze the reactionat room temperature in water. The comparable advantages，including short reaction time,good product selectivity and yield higher, conformed to the requirements of green chemistry.In addition, the mechanism of these reactions had been investigated. The results showed thatthe urea component of this catalyst would operate via activation of the aldehyde while thepyridine unit serves as an internal organic base which would deprotonate the Meldrum’sacid nucleophile.In Chapter4and5, we also reported a chiral tertiary amine used in asymmetricKnoevenagel condensation reaction. The chiral organocatalysis was prepared from S,S-Cyclohexanediamine by three-step reaction, and the space configuration was confirmed byX-ray single crystal diffraction. With2-phenyl propionic aldehyde and diethyl malonate astemplate substrates, the optimal reaction conditions were determined by the single factorexperiments of solvent, reaction time, reaction temperature and the dosage of catalyst. Theproducts were also characterized by1HNMR, MS, and HPLC, etc.