Substitution reactions of β-dicarbonyl compounds and enole eters

In this study, alkylation reactions of acetylacetone and dibenzoylmethane which are known as 1,3-dicarbonyl compounds with n-butyl vinyl eter, 3,4-dihydro-2H-pyran (DHP), 2,3 dihydrofuran and enone derivative was studied in the presence of acidic catalyst Amberlyst-15. Characterization of products by convenient methods after purification were investigated and included in this study as well. The alkylation of 1,3-dicarbonyl compounds is a useful transformation involving C-C bond formation. There are several techniques applied in the literature and nucleophilic substitution of the hydroxyl group technique studied in our group before is one of them. In principle, direct nucleophilic substitution of the hydroxyl group in alcohols with nucleophiles generally requires preactivation of the alcohol because of its poor leaving ability.Therefore, hydroxyl groups are generally converted into some appropriate groups, which can easily leave from compounds. However, transforming hydroxyl group requires high temperatures or usage of catalyst. In most cases, Lewis acides are chosen as a catalyst during the reactions. Most of Lewis acides works well only with allylic alcohols but not wth benzylic alcohols.Because of requiring, the harsh conditions, long reaction times, high temperatures, and use of expensive, toxic and moisture sensitive reagents in most of the above methods, the practical utility in organic synthesis has been limited . Herein, we report Amberlyst-15 as an acidic catalyst for direct carbon-carbon bond formation between active methylene compounds and various benzylic or allylic alcohols with fewer purification steps, short reaction time, lower temperature. We obtained that usage of base is given same products with Michael addition mechanism. However, during the reactions we did not use any base. According to this, we obtained that the mechanism of reaction is occured like carbocation mechanism. For our initial studies, we started with alkylation reaction between acetylacetone with 2,3-dihydrofuran and 4-metoxy-3-butene-2-one in the presence of Amberlyst-15 catalyst. The alkylated product was obtained in short time and with considerable yield. Further reactions, we used same conditions of those two reactions.