A green synthesis of highly substituted 1,5-diketones

Abstract

The advantages of the aqueous reactions over the conventional ones were demonstrated in the synthesis of highly substituted 1,5-diketones.Highly substituted 1,5-diketones have been synthesized in water via the reactions between aryl methyl 5 ketones and aldehydes and the subsequent dimerizations. The reaction was catalyzed by aqueous KOH. The advantages of these aqueous reactions over organic-solvent mediated reactions are better yields, better diastereoselectivities, faster reaction rates, simpler workups, and more energy efficient. The reaction can be scaled up to 13.9-gram scale and the aqueous KOH can be reused for five cycles. A possible mechanism is proposed to explain the high diastereoselectivities.

Improved dispersion of reduced graphene oxide in benzoxazine composites via electrostatic interaction with M‐cresol

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Dynamic Pluronic F127 Crosslinking Enhancement of Biopolymeric Nanocomposites for Piezo‐Triboelectric Single‐Hybrid Nanogenerators and Self‐Powered Sensors

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One-Pot Synthesis of 1,5-Diketones under a Transition-Metal-Free Condition: Application in the Synthesis of 2,4,6-Triaryl Pyridine Derivatives

“…General Procedure for the One-Pot Synthesis of 1,5-Diketones. 17,[22][23][24][25]65,66 To a stirred solution of acetophenone derivatives 1a−t (0.540−0.832 mmol, 1 equiv) in ethanol (EtOH) (1.5 mL), 60% aqueous solution of KOH (0.54−0.832 mmol, 1 equiv) was added and the mixture was stirred at 0 °C for 0.25 h. After the enol is formed, the aldehydes 2a−t (0.54−0.832 mmol, 1 equiv) were added to the reaction solution at the same temperature. Less amount of dichloromethane (0.5 mL) was added to dissolve for those aldehydes such as 2b, 2c, 2e, 2h, 2j, 2p, and 2r, which were not soluble in EtOH.…”

“…These heterocycles have important applications in modern drug design and in the chemistry of functional materials . Consequently, much effort has been devoted to the chemical synthesis of 1,5-diketones. ,, The most common classical methods of 1,5-diones synthesis are (i) Claisen–Schmidt condensation following Michael addition reaction of aryl methyl ketones and benzaldehyde derivatives under a basic condition − and using silica vanadic acid as a heterogeneous catalyst (Scheme a), (ii) catalyzed Michael reactions of chalcones (α,β-unsaturated ketones) with aryl methyl ketones, silyl enol ethers, , and diphenacyl sulfides (Scheme b), (iii) from α,β-unsaturated ketones via base-induced retro-aldol and Michael addition using copper and cobalt as catalysts, , (Scheme c), (iv) via nickel on silica-alumina-catalyzed direct α-alkylation of aryl methyl ketones with benzyl alcohol (Scheme d), and (v) silver- and rhodium-catalyzed reactions of aromatic and aliphatic aldehydes with cyclopropanol and cyclobutanol derivatives. , However, these synthetic methods use expensive catalysts and additives, toxic organic solvents, and air- and moisture-sensitive materials. Additionally, the yields of 1,5-diketones through these reactions were low either due to by-product formation such as aromatic aldehydes , or no product formation at all under base-mediated condensation .…”