Fly ash supported scandium triflate as an active recyclable solid acid catalyst for Friedel–Crafts acylation reaction

A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles

“…The slightly lower yields of 3-acylated products are due to increased substitution at the 1-and 2-position (Table 3, entries 7-18). However, acylation of 4-or 5-haloindoles with aliphatic acid anhydrides produced 3-acylindoles in good yields (Table 3, entries [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. In addition, N-acylated byproducts were slightly decreased in comparison with electron-rich indoles, but 2-acylindoles were obtained in small amounts (Table 3, entries [19][20][21][22][23][24][25][26][27][28][29].…”

“…Although metal triflates have been applied extensively in Friedel-Crafts acylation of aromatic compounds [24][25][26][27][28], there has been only one report on the use of indium triflate for the acylation of indoles [29]. However, in that case, excess reagent and NH-protection were required to obtain 3-acylated indoles in good yields.…”

Catalytic applications of waste derived materials

“…In addition to the preceding reaction classes, waste heterogeneous catalysts are reported for epoxidation, 166 dehydration, 167 ethanolysis, 168 condensation 169 and acylation. 170 Pyrolysed waste tires were used to derive a support for chiral Mn-salen complexes for the asymmetric epoxidation of unfunctionalised olens. 166 This thermally stable microporous support had a surface area of 85 m 2 g À1 , but lost 3% of its Mn content due to leaching over three successive recycles.…”

“…A solid acid catalyst composed of y ash-supported scandium triate was showed superior activity than zeolite beta and La 3+ ion exchanged zeolite beta in the Friedel-Cras acylation of 2-methoxynaphthalene to form 2-acetyle-6-methoxynaphthalene, a naproxen precursor. 170 The authors suggested that the y ash catalyst could replace zeolite beta in industrial applications, such as the preparation of the anti-inammatory drug naproxen, due to its superior activity and selectivity. The y ash catalyst was shown to be active when reused in four reaction cycles, where conversion fell from 84 to 77%.…”

An Efficient and Green Synthesis of 1‐Indanone and 1‐Tetralone via Intramolecular Friedel–Crafts Acylation Reaction

“…[5,[7][8][9][10] Metal triflates are efficient and green catalysts for Friedel-Crafts acylation. [11][12][13][14][15][16][17][18][19][20][21][22] Recently, metal-triflate-catalyzed Friedel-Crafts acylation with carboxylic acids as the acylating reagents has been studied extensively. [23][24][25][26][27] Although the intramolecular Friedel-Crafts acylation of carboxylic acids has been catalyzed by metal triflates with only 5-10 %c atalytic loading, the requirement for volatile organic solvents and long reactiont imes are current shortcomings.…”