Study On Synthesis Of Caffeic Acid Ester Derivatives And Their Biologic Activities

In this dissertation, it was studied that the synthesis of caffeic acid ester derivatives as a kind of natural drugs and their biological activities. There are four achievements provided such as:1 It was found a new method for preparation of caffeic acid esters by Knoevenagel- Doenber condensation. There are 2 new strategies. One is "malonic acid mono-ester method" presented as follow: Malonate diesters were prepared by diphenylammonium triflate (DPAT) catalyzed esterification between malonic acid and alcohols; then malonic acid mono-esters were prepared from the corresponding malonate diesters by equivalent saponification and then acidification; 3,4-dihydroxybenzalde-hyde was reacted with malonic acid mono-esters by Knoevenagel-Doebner condensation to afford the desired caffeic acid esters in good yield. Another method improved from the aforementioned method is a convenient one-pot synthetic method which was established as follows: the malonic acid mono-esters were prepared in quantitative yields by reaction of the corresponding alcohols with 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid); then the malonic acid mono-esters without separation from the mixtures underwent modified Knoevenagel condensation with 3,4-dihydroxybenzaldehyde to afford the desired esters. As a result, 19 compounds including 14 new compounds were synthesized by these 2 methods. The methods are operating easily, mild...