“…1 [19]. Due to the above listed excellent therapeutic applications of the 1,4-dihydropyridine derivatives, synthetic chemists have explored several protocols for the synthesis of them using different reaction conditions and varied catalytic systems as follows: Yb(OTf) 3 [20], [pyridine-SO 3 H]Cl [21], [Dsim]HSO 4 [22], Triton X-100 in water [23], TiO 2 NPs [24], SnO 2 NPs [25], silica-bonded imidazolium-sulfonic acid chloride [26], [2-MPyH]OTf [27], SBA-15/SO 3 H [28], Ninanoparticles [29], IL-HSO 4 @SBA-15 [30], Baker's yeast [31], Lproline [32], and [bmim]BF 4 [33]. Although the reported methods offer several merits and provide improvements for the synthesis of the target molecules, many of these protocols need longer reaction times, hard reaction conditions, using unsafe organic solvents, and drastic workups.…”