Organic Base Catalyzed Reactions Based On Electron-Deficient Alkyne

The zwitterions formed from the addition of organic base to electron-defecient alkyne are a class of important dipolar species. We have pursued some reactions based on the zwitterions withβ-dicarbonyl moieties, aldehydes, benzophenone Schiff base derivatives of glycine esters. We developed the approach of synthesis of highly substituted benzenes andα,β-dehydroamino acid derivatives through the reaction of activated methenes with the zwitterions; and developed a multi-component reaction ofβ-dicarbonyl moieties, acetylenic ketones and aldehydes catalyzed by triphenylphosphine; and a cycloaddition of aldehydes with acetylenic ketones catalyzed by DMAP. This article is made up of seven sections.1. A facile and mild process for synthesis of olefins bearingβ-dicarbonyl moieties based onα-addition ofβ-dicarbonyl moieties to acetylenic ketones catalyzed by triphenylphosphine was developed.2. A multi-component reaction ofβ-dicarbonyl moieties, acetylenic ketones and aldehydes catalyzed by triphenylphosphine was developed. The method supplies a facile way to synthesis multi-carbonyl compounds. A plausible mechanism is proposed for this multi-component reaction.3. An efficient isomerization of alkynyl ketones to (E,E)-diene ketones was developed. The reaction catalyzed by triphenylphosphine in aqueous media gave the desired products.4. A new organocatalytic process of cyclotrimerization of acetylenic ketones was developed, which procedure catalyzed by DMAP in the presence of 2,4-pentanedione as co-catalyst gave 1,3,5-trisubstituted-benzenes with almost quantitative yields under mild conditions. And cross cyclotrimerization of two different acetylenic ketones was investigated.5. DMAP-catalyzed benzannulation reaction of ethyl propiolate withβ-dicarbonyl compounds at room temperature providing highly substituted benzenes was developed. A possible mechanism for the benzannulation reaction is proposed.6. A cycloaddition of aldehydes with acetylenic ketones catalyzed by DMAP was developed. The method supplies a facile way to synthesis 3,4,5-trisubstituted-4H-pyrans in moderate to good yields. A plausible mechanism is proposed for this process. 7. A mild and efficient process for synthesis ofα,β-dehydroamino acid derivatives through Et₃N-promoted michael addition of activated alkynes with benzophenone Schiff base derivatives of glycine esters was developed.Through these rsearches, we extened the appliacation of the zwitterions formedfrom the addition of organic base to electron-defecient alkyne and developed newapproach to synthesis of highly substituted benzenes andα,β-dehydroamino acidderivatives.