Brønsted acidic surfactant [HDMM]+ [HSO4]−: a green microreactor assembly for stereoselective synthesis of novel thiazolyl-pyrazole-chromen-2-ones in water†

Abstract

A novel Brønsted acidic surfactant was synthesized and employed as a catalyst for a one-pot multi-component reaction. Small angle X-ray scattering (SAXS) analysis was performed, which confirmed that the micelles exhibited an average diameter of 3.1 nm and average inter-micellar distance of 0.49 nm. Ground state density functional theory (DFT) calculation was performed on the surfactant molecule to optimize the geometrical structure. A series of novel thiazolyl-pyrazole-chromen-2-one derivatives were efficiently synthesized through a convenient one-pot multi-component reaction of substituted 3-acetoacetyl coumarins, thiosemicarbazide and dialkyl acetylene dicarboxylates in water using a novel hexadecyl methyl morpholinium hydrogen sulfate [HDMM]⁺ [HSO₄]⁻ as surfactant. Operational simplicity, stereoselective synthesis, quick access to the desired products, high purity and good to excellent yields are the key advantages of this approach. This work remarkably highlights the dual novelty as a new class of thiazolyl-pyrazole-chromen-2-one derivatives as well as a [HDMM]⁺ [HSO₄]⁻ surfactant.