The Cerium Salt Catalyzed 1,3 - Dicarbonyl Compounds The Propargyl Of And The One-pot Synthesis Of Polysubstituted Furans

As we all know, in recent years, Lewis acid catalysts in organic synthesis are widely used. Cerium chloride as an usual Lewis acid, compared with BF3,SbF5,AICl3, have many advantages such as being able to bear non-toxic, water, gentle and good selectivity. Cerium compounds have a fine application, and they can catalyze many organic reactions under mild reaction condition effectively. Because of the cheap price, being able to act under mild, non-toxic condition, the use of Cerium(Ⅲ) as a catalyst is paid more and more attention. In this thesis, the cerium chloride as the main catalyst was used in a series of catalytic reactions, and the specific work we have done are displayed:First, in order to synthesize the raw compounds required for the reaction,we first studied the zinc chloride (Ⅱ) proceeding the reaction of benzaldehyde and its derivatives with alkynes. Zinc compounds as catalyst, in EtN3 and toluene,The compounds were heated to 35℃, stirring 14h, and obtained the target product:propargyl alcohol, light yellow oil bar, the yield was 93%.Second, after obtaining the target product propargyl alcohol, we studied the cerium compounds as a catalyst for the reaction of propargyl alcohol and 1,3-dicarbonyl compounds.Propargylation ofβ-dicarbonyl compounds was paid more attention by Lewis acid catalysis. As it is known, CeCl3·7H2O/NaI catalyzed the nucleophilic substitution reaction of propargyl alcohol and acetylacetone heated to reflux(85℃) for 10h Under nitrogen atmosphere in dichloroethane solvent, the yield was 55.3-92.1%.Finally, we studied the cerium-catalyzed synthesis of polysubstituted furans. Many drugs and natural products existing in nature belong to the furan compounds, the synthesis is extremely important, especially in the synthesis of polysubstituted furan compounds. More and more people concern about it. We use cerium(III) compounds as the catalyst, to proceed the synthesis of four substituted furan compounds effectively. Propargyl alcohol and 1,3-dicarbonyl compounds was heated to reflux in toluene under the protection of nitrogen,stirring for 12-24h, to obtain the target product, the yield was 54.3%-86.3%. Our method compared with the traditional synthesis methods, requires no stop during the middle of the reaction and adding another catalyst. Only Using a catalytic amount of CeCl3·7H2O/HOAc realizes "one-pot" synthesis of four substituted furan compounds.From above results, on one hand, cerium chloride as Lewis acid in catalysis has been more widely used; the other hand, for the synthesis of tetrasubstituted furans, our method provided a new effective way to synthesize substituted furan compounds.