Basic Ionic Liquid Promoted Domino Knoevenagel–Thia‐Michael Reaction: An Efficient and Multicomponent Strategy for Synthesis of 1,3‐Thiazines

Abstract

in Wiley Online Library (wileyonlinelibrary.com).An efficient, three-component strategy for synthesis of 1,3-thiazines with high atom economy in one-pot mediated by room temperature basic ionic liquid is described here. The strategy involves basic ionic liquid, [bmim]OH-catalyzed Knoevenagel condensation between ethyl cyanoacetate and aromatic aldehyde and subsequent thia-Michael addition with substituted thioureas. The reaction sequence is smooth and quantitative under ambient temperature.[bmim]OH was recovered and reused four times without any appreciable decrease in its reactivity and product yield.

Rapid and Efficient Uncatalyzed Knoevenagel Condensations from Binary Mixture of Ethanol and Water

“…These results are in agreement with the mechanism of these amine-free reactions. 42 This mechanism is well known to involve carbanion formation and an ionic intermediate (enolate). Therefore, the reaction in a polar solvent (thf, for example) would be expected to be faster than in an apolar solvent (toluene, for example).…”