Green Tandem [5C + 1C] Cycloaromatization of α-Alkenoyl Ketene Dithioacetals and Nitroethane in Water: Eco-Friendly Synthesis of Ortho-Acylphenols

Abstract

For the first time, an eco-friendly and sustainable tandem [5C + 1C] cycloaromatization of α-alkenoyl ketene dithioacetals and nitroethane in water for the efficient synthesis of ortho-acylphenols was reported. In refluxing water, a range of α-alkenoyl ketene dithioacetals and nitroethane smoothly underwent tandem Michael addition/cyclization/aromatization reactions in the presence of 2.0 equivalents of DBU to provide various ortho-acylphenols in excellent yields. The green approach to ortho-acylphenols not only avoided the use of harmful organic solvents, which could result in serious environmental and safety issues, but also exhibited fascinating features such as good substrate scope, excellent yields, simple purification for desired products, ease of scale-up, and reusable aqueous medium.

K2CO3-accelerated amidation of carboxylic acids using α-oxo ketene-N,S-acetals as amine surrogates

“…α-Oxo ketene- N , S -acetals 13 are unique reagents with multi-reactive sites, and possess the character of both the α-oxo ketene- S , S -acetal 14 and enaminone 15 substrates. They are essentially active α,β-unsaturated ketones, which are internally activated by electron-releasing alkylthio and amino groups through p–π conjugation.…”

Catalyst- and additive-free [3 + 3] cyclization–aromatization of β,γ-dioxobutanoate with amines for synthesis ofp-aminophenols

“…In recent decades, metal-, 1 organo-, 2 acid- 3 and base-catalysed 4 cyclization–aromatization reactions of non-aromatic compounds have been recognized as promising methods for the formation of aromatic structures. In this context, carbonyl compounds are commonly employed as reactants.…”