Acid-catalyzed, regioselective [3+3] annulation of enaminones and α-substituted cinnamic acids: access to 3,4-dihydropyridones and 2-piperidinones

An efficient strategy for the synthesis of structurally diverse 3,4-dihydropyridones and 2-piperidinones is reported. The former was prepared via acid-catalyzed Michael addition of enaminones to electron-deficient alpha-substituted cinnamic acids followed by lactamization, whereas the latter was synthesized by the same methodology except that cinnamic acids were replaced with coumarin 3-carboxylic acids. A unique regioselective reactivity of the enaminones toward different cinnamic acid derivatives is described.

Automated summary

An efficient strategy for synthesizing structurally diverse 3,4-dihydropyridones and 2-piperidinones is described in this study. The former is prepared through acid-catalyzed Michael addition of enaminones to electron-deficient alpha-substituted cinnamic acids followed by lactamization, while the latter is synthesized through the same methodology using coumarin 3-carboxylic acids instead of cinnamic acids. The unique regioselective reactivity of enaminones towards different cinnamic acid derivatives is highlighted.