Synthesis of (E)-2-Styrylchromones and Flavones by Base-Catalyzed Cyclodehydration of the Appropriate β-Diketones Using Water as Solvent

Abstract

A low cost, safe, clean and environmentally benign base-catalyzed cyclodehydration of appropriate β-diketones affording (E)-2-styrylchromones and flavones in good yields is disclosed. Water was used as solvent and the reactions were heated using classical and microwave heating methods, under open and closed vessel conditions. β-Diketones having electron-donating and withdrawing substituents were used to evaluate the reaction scope. The reaction products were isolated in high purity by simple filtration and recrystallization from ethanol, when using 800 mg of the starting diketone under classical reflux heating conditions.

Chromones: Privileged scaffold in anticancer drug discovery

“…Recent literature reports application of synthetic methodologies having advantage of environment friendliness, high yield, shorter reaction time, and ease of use. Few examples include Use of water as solvent along with classical and microwave‐assisted heating for synthesis of ( E )‐2‐styrylchromones (Pinto et al, 2015). Metal‐ and solvent‐free one‐pot synthesis of 3‐Se/S‐Chromones from the cyclization of enaminones in the presence of dichalcogenides catalyzed by KIO 3 to get excellent yield (Rafique et al, 2017).…”

The Potential of Cryptophyte Algae in Biomedical and Pharmaceutical Applications

“…A specific class of flavonoids, 2-styrylchromones (2-SC, C 17 H 12 O 2 ), was extracted from the marine cryptophyte Chrysophaeum taylori in 1986 by W. H. Gerwick ( Gomes et al, 2010 ). Certain analogues of these components have been synthesized and assessed in biological systems, showing that both the natural and synthetic compounds possess a myriad of biological activities ( Table 6 ) including anti-allergic, anti-tumor ( Li et al, 2007 ), antioxidant, antimicrobial, antiviral, anti-inflammatory ( Madhava Rao et al, 2016 ), antifungal, hepatoprotective ( Pinto et al, 2015 ), anti-infective, immune system promoting and skin protective from UV radiation ( Gomes et al, 2010 ; Tungmunnithum et al, 2018 ). This clearly demonstrates the ability of cryptophytes to produce complex phenolic compounds.…”

An Overview of 2‐Styrylchromones: Natural Occurrence, Synthesis, Reactivity and Biological Properties

“…[64,70,74] It has been replaced by use of milder reagent systems, including the use of a few drops of diluted hydrochloric acid in acetic acid, [73] of p-toluenesulfonic acid (PTSA) in DMSO [13,18,19,7,8,65,67,68,72] or of a catalytic amount of iodine in DMSO. [13,18,8,45,68] Individual attempts with use of concentrated sulfuric acid in ethanol at reflux, [66] grinding with phosphorus pentoxide under solventfree conditions [76] and with potassium carbonate in water under classical heating at reflux or under microwave-assisted conditions [77] have also been reported (Scheme 8). Nikam et al performed a three-step approach to the synthesis of 2-SCs and compared the use of classical heating conditions and of ultrasound irradiation.…”