Highly Efficient Low Melting Mixture Catalyzed Synthesis of 1,8‐Dioxo‐dodecahydroxanthene Derivatives

Abstract

A low melting citric acid‐urea mixture was found to be a new and effective promoting medium for the environmentally friendly synthesis of 1,8‐dioxo‐dodecahydroxanthene derivatives by condensation of aromatic aldehydes and cyclic 1,3‐dicarbobonyl compounds. This deep eutectic solvent acts as both the reaction medium and catalyst, furnishing xanthenediones in high to excellent yields.

Deep Eutectic Solvents: The Organic Reaction Medium of the Century

“…For the latest, recyclability was studied observing a small loss of activity after 6 cycles. [60] Scheme 8. Synthesis of xanthene derivatives.…”

A Green Method for Synthesizing Nickel Nanoparticles Supported by Magnetized Pectin: Applied as a Catalyst for Aldehyde Synthesis as a Precursor in Xanthan Synthesis

“…Pectin has carboxylic acid groups that can act as a covalently chelating agent to Fe 3 O 4 nanoparticles and direct the nanostructure. A general schematic for the synthesis of Fe 3 O 4 @Pectin@Ni (II) is shown [30] 2 60 87 260-262 262-264 [30] 3 55 88 253-255 255-256 [31] 4 55 92 281-283 286-288 [30] 5 50 85 247-249 248-250 [30] 6 50 88 202-203 200-202 [30] 7 60 90 283-285 284-286 [30] 8 70 80 241-243 240-242 [32] [a] (Figure 1). FT-IR spectrum of Pectin (Figure 1a) shows characteristic peaks at 3400-3600 cm À 1 (OÀ H stretching alcoholic and acidic), 923 cm À 1 (CÀ H stretching), 1725 cm À 1 (C=O of ester), 1618 cm À 1 (COOasymmetric stretching), 1412 cm À 1 (COOsymmetric stretching), The FT-IR spectrum of Fe 3 O 4 ( Figure 1b) the stretching vibrations FeÀ O and OÀ H at 574 cm À 1 and 3420 cm À 1 that allow the establishment of Fe 3 O 4 nanoparticles.…”

Deep Eutectic Solvents in Organic Synthesis

“…A closely related acidic DES -citric acid/DMU -was found to be superior to TTA/DMU for the synthesis of 1,8-dioxo-dodecahydroxanthenes. [68] (Scheme 36) A wide range of aldehydes afforded good results under these reaction conditions and the DES could be recycled up to six times with little loss of activity. Recycling again involved the recovery of the DES from the aqueous layer via concentration in vacuo.…”