Synthesis of 3,4-dihydropyrimidin-2(1H)-ones and 1,4-dihydropyridines using ammonium carbonate in water

Synthesis and antioxidant evaluation of novel 4-aryl-hexahydroquinolines from lignin

“…Recently, the progress in the field of reactions in aqua media is gaining significance because of their operational simplicity and environmentally benign processes. Herein, we wished to develop a new eco-friendly procedure [27][28][29] with our continuation to the use of the microwave technology for MCR for efficient and catalyst-free synthesis of polyhydroquinolines in water (Schemes 2). According to green chemistry concept, water was used as the solvent.…”

“…Ammonium carbonate was chosen as a solid ammonia source because it has low toxicity (LD50 1497 mg/kg) and melting point (58 o C) and resulted in high yields compared with ammonium acetate, ammonium chloride, or ammonium nitrate etc. 28 The microwave irradiation can accelerate reaction rate, shorten reaction time, and improve product yields by transferring energy directly to the reactive species. 30,31 Thus, the four-component reactions between the aromatic aldehydes, 1,3-cyclohexanediones, β-ketoesters, and ammonium carbonate were conducted in water under microwave irradiation without any catalysts in a short time providing the desired polyhydroquinolines in high yields.…”

Основні Напрями Розвитку Хімії 1,4-Дигідропіридинів – Огляд Літератури

“…Исследования F. Tamaddon [58], связанные с поиском оптимального источника азота в синтезе 1,4-ДГП Ганча (2.7), показали, что среди аммонийных солей с различными анионами (хлоридом, ацетатом, сульфатом, нитратом, молибдатом, гидрокарбонатом и др.) максимальный выход продукта (99%) обеспечивает использование карбоната аммония в водной смеси ароматического или гетероциклического альдегида и алкил ацетоацетата в условиях перемешивания при 55-60 0 С (схемa 5).…”

A simple and efficient approach for synthesis of 1,4-dihydro-pyridines using nano-crystalline solid acid catalyst

“…However, the yield of 1,4-DHP obtained by Hantzsch method is generally low [13][14][15]. Various methods for the synthesis of dihydropyridine derivatives are described in the literature including condensation of aromatic aldehydes, β-dicarbonyl compounds and ammonium acetate using of microwave [16], ionic liquids [17], tetrabutylammonium hydrogen sulfate [18], silica gel/NaHSO 4 [19], AlCl 3 .6H 2 O [20], TMSI [21], triphenylphosphine [22], InCl 3 [23], I 2 [24], cellulose sulfuric acid [25], alumina sulfuric acid [26], SiO 2 /HClO 4 [27], metal triflate [28], Fe(CF 3 CO 2 ) 3 [29], nano CuO [30], nano MgO [31], ultrasound irradiation [32], solvent free [33], and aqueous media [34].…”