An efficient method for the synthesis of acylals from aldehydes using silica-supported perchloric acid (HClO4–SiO2)

ZSM-5-SO3H as a novel, efficient, and reusable catalyst for the chemoselective synthesis and deprotection of 1,1-diacetates under eco-friendly conditions

“…The high catalytic activity, low toxicity, moisture and air tolerance, recyclability, and particularly their low price make the use of solid supported reagents an attractive alternative to conventional acids. Some of the solid supported acids, e.g., SiO 2 -OSO 3 H [29] and HClO 4 -SiO 2 [42], are utilized as catalysts for the preparation of 1,1-diacetate derivatives from the corresponding aldehydes. Recently, we have demonstrated the applicability of SiO 2 -OSO 3 H [43], H 3 PO 4 /TiO 2 -ZrO 2 [44,45], H 3 PO 4 /ZSM-5 [46], SiO 2 -OPO 3 H [47], and SiO 2 -Cl [48] as solid supported acids in several organic transformations.…”

A convenient synthesis of coumarinyl chalcones using HClO4–SiO2: A green approach

“…In this context, HClO 4 -SiO 2 is a suitable candidate for various organic reactions due to its inherent properties such as high acidity, efficiency, stability, inexpensiveness, recyclability, selectivity, operational simplicity, non-corrosiveness, moisture-insensitivity and easy handling etc (Das et al, 2006, Chakraborti andGulhane, 2003). It has been successfully employed for numerous organic reactions, such as protection of hydroxyl groups (Shaterian et al, 2007), acetylation of phenols, thiols, alcohols, amines (Chakraborti and Gulhane, 2003), synthesis of xanthenes / substituted coumarins (Maheswara et al, 2006)/ chromenyl pyridines (Ghashang et al, 2014)/ β-keto enol ethers / quinoxalines and dihydropyrazines / flavans (Bharate et al, 2012)/ enaminones and enamino esters / acylals (Kamble et al, 2006) and chemoselective carbon sulfur bond formation (Khatik et al, 2007). It has been also applied in Hantzsch (Dasri et al, 2011), Winkler (Heydari and MaMani, 2008), Mannich and Biginelli (Maheswara et al, 2008) reactions.…”

Silica Supported Perchloric Acid: A Convenient and Environmentally Friendly Catalyst for the One‐pot Multicomponent Synthesis of β‐Acetamido Ketones

“…22 In recent years, using of solid supported acids have become more important in synthetic organic chemistry due to some advantages such as enhanced selectivity, reactivity and easy product isolation. 23 Silica supported perchloric acid (HClO 4 -SiO 2 ) has received considerable attention for numerous organic transformations, including acylation of alcohols 24 or aldehydes, 25 the Ferrier rearrangement, 26 cleavage of benzylidene acetals, 27 electrophilic substitution of indole with various aldehydes and ketones, 28 synthesis of Hantzsch dihydropyridine, 29 homoallylic amines through a three-component reaction, 30 tetrasubstituted imidazoles under solvent free conditions 31 and 1,8-dioxo-octahydroxanthenes via Knoevenagel condensation. 32 In view of its inherent properties like environmental friendly, greater selectivity, operational simplicity, non-corrosive nature, moisture-insensitive and ease of isolation, it is therefore, interesting to find out the behavior of the catalytic system in the synthesis of β-acetamido ketones.…”