Molecular iodine-catalyzed one-pot synthesis of some new Hantzsch 1,4-dihydropyridines at ambient temperature

Abstract

An efficient and simple one-pot synthesis of some new symmetrical, unsymmetrical and Nsubstituted Hantzsch 1,4-dihydropyridines using molecular iodine as catalyst from an aldehyde, a 1,3-dicarbonyl compound and ammonium acetate / aromatic amine in ethanol is described. This new method has the advantage of good to excellent yields (80-95%) and short reaction times (2.5-5 h) at ambient temperature.

Molecular iodine-catalyzed multicomponent reactions: an efficient catalyst for organic synthesis

“…Meanwhile, the reaction times and yields of reactions were not seriously changed but purification of crude products of the method A was more easier than methods B and C. Similarly, aniline also was employed for synthesis of N-aryl-1,4-dihydropyridine 15 and 16 with good yields (Scheme 11). 26,27 2.5 Strecker-type reaction a-Aminonitriles are usually synthesized by the nucleophilic addition of a cyanide anion to imines. The Strecker-type reaction provides one of the most efficient methods for the synthesis of a-aminonitriles 17 and 18 (Scheme 12).…”

Silica Sulfuric Acid: An Efficient Heterogeneous Catalyst for the One-Pot Synthesis of 1,4-Dihydropyridines under Mild and Solvent-Free Conditions

“…Since then a series of procedures have been developed for the synthesis of DHPs. The reported procedures involve the use of reagents and catalysts such as Montmorillonite K10 [13], TBAB [14], HClO 4 ·SiO 2 [15], I 2 [16], silica gel/NaHSO 4 [17], AlCl 3 ·6H 2 O [18], 2,4,6-trichloro[1,3,5]-triazines (TCT, cyanuric chloride) [19], ionic liquid/3,4,5-trifluorobenzeneboronic acid [20], sulfonic acid [21], and fermenting bakers' yeast [22] under various conditions such as ultrasound [23], microwave irradiation [24], and high temperature in refluxing solvent [25]. Moreover, procedures involving use of β-enaminones [26] as substrates have also been reported for the synthesis of DHPs.…”