First application of hexaaquaaluminium(III) tetrafluoroborate as a mild, recyclable, non-hygroscopic acid catalyst in organic synthesis: a simple and efficient protocol for the multigram scale synthesis of 3,4-dihydropyrimidinones by Biginelli reaction

A microdroplet-accelerated Biginelli reaction: mechanisms and separation of isomers using IMS-MS

“…Product 4 was detected instantly. Since this reaction produces only trace products in methanol (see ESI †) and acetonitrile at 48 hours, 55 the microdroplet-catalyzed variant represents a signicant rate enhancement. To quantify the rate enhancement, we used a theta-glass, double-barrel, capillary where a mixture of two reagents (e.g., 1 and 2) was sprayed from the rst barrel, and the remaining reagent (e.g., 3) was sprayed from the second barrel ( Fig.…”

“…This represents a massive acceleration relative to control bulk-phase reactions. 55 This acceleration presumably arises as the microdroplet evaporates, a process that leads to high concentrations of reagents in conned spaces. Additional factors such as change in pH, 27,28 droplet size, 28,29 reagent concentration, 28,34,46 solvent system, 17,30 and droplet temperature, 30,31 may also inuence these reactions.…”

Green High-Yielding One-Pot Approach to Biginelli Reaction under Catalyst-Free and Solvent-Free Ball Milling Conditions

“…Despite all of the improved methods, organic synthesis methods still have many drawbacks, such as the use of organic solvents, long reaction times, high costs, low yields, nonsustainable catalysts, and purification issues [34][35][36][37][38][39][40].…”

Succinic Acid As a Green and Bio-Based Catalyst assisted solvent-free one-pot Biginelli synthesis of biologically active 3,4-dihydropyrimidin-2-(1H)-ones/thiones derivatives

“…Recently, numerous protocols for the preparation of these compounds that is including various catalysts have been reported calcium fluoride (Chitra et al, 2009), copper(II)sulfamate (Liu et al, 2009), baker's yeast , hydrotalcite (Lal et al, 2012), hexaaquaaluminium (III) tetrafluoroborate (Litvic et al, 2010), TBAB (Ahmad et al, 2009), copper (II) tetrafluoroborate (Kamal et al, 2007), Copper (II) acetate (Khodja et al, 2014), [Btto][p-TSA] (Zhang et al, 2015), triethylammonium acetate (Attri et al, 2017), p-dodecyl-benzenesulfonic acid (Aswin et al, 2014) and TMSPTPOSA (Rao Jetti et al, 2017). Some of the limitations of these methodologies are low yields, toxic organic solvents and catalyst, harsh reaction conditions and expensive materials.…”