An effective process for the synthesis of dihydropyridines via SO₄⁻²/SnO₂‐catalyzed Hantzsch reaction

Abstract

Sulfated tin oxide (STO) was established as an admirable heterogeneous catalyst for the single‐step synthesis of dihydropyridine derivatives via Hantzsch reaction. The synthetic method was mainly used in the presence of STO as a heterogeneous solid catalyst. STO‐catalyzed Hantzsch reaction afforded good yields (90–94%) in acetonitrile at 80°C. The synthesized titled compounds were characterized and confirmed by High Resolution Mass Spectroscopy (HRMS), Fourier Tranform‐Infrared (FTIR), 1H and 13C‐NMR, and spectral data.

Synthesis of Bioactive 1,4‐DHPs Using Sulfated Tin Oxide as an Efficient Solid Superacid Catalyst

“…Sulfated tin oxide was synthesized using the method given in literature. [ 23,24 ] Fifty gram of stannous chloride was dissolved in 150 mL water. The pH of the solution was adjusted to 8 using 25% ammonia solution.…”

“…It was used as an excellent catalyst in aldol condensation, synthesis of triaryl imidazole derivatives, liquid phase selective dehydrogenation of sorbitol, synthesis of coumarin, chromone synthesis, [ 22 ] some bioactive DHPs. [ 23 ] The STO catalyst has several advantages, such as easy preparation, nontoxic, cheap, highly selective, and environmentally benign with good yield, and it is stable in air, moisture, and heat. [ 24 ] As a part of our research on the development of green, synthetic methodologies and considering the catalytic advantages of STO, we have prepared sulfated tin oxide NPs and explored its synthetic utility.…”

Applications of Sulfated Tin Oxide (STO) in Organic Synthesis - from 2016 to 2021

“…7,8 They exploited STO as an excellent heterogeneous catalyst for the one-pot synthesis of dihydropyridines derivatives via Hantzsch reaction using substituted aldehydes, NH4OH and acetoacetanilide in acetonitrile at 80 °C (Scheme 2). 9 No significant loss of the efficiency of the catalyst was observed even after five cycles. The mechanism of this reaction proceeds STO as Brønsted acid catalyst, initially through a Michael addition, followed by an intramolecular tandem sequence, that may take place in the formation of the final product.…”

Pyranoquinolone derivatives: A potent multi‐targeted pharmacological scaffold

“…Animal studies on these substances' cardiovascular properties revealed no potential benefits on the circulatory systems of rats, dogs, or guinea pigs [87,88]. Additionally, the development of IgE antibodies and their allergenic effects was taken into account [48]. These substances elicited identical asthmatic behaviors in rodents as those seen with cromolyn sodium 10 mg/kg [55,56,87,88].…”

“…Some of the most important biological roles of derivatives have really been demonstrated, especially their bacteriostatic and bactericidal characteristics [8,9,45,46]. Because of this, a new strategy based on quick reaction times and a high-quality but low-cost catalyst is required to develop environmentally friendly pyranoquinolone synthesis techniques that improve yields [47][48][49]. Pyran rings (six-membered rings with one oxygen heteroatom) [50,51] and quinoline rings combine to generate pyranoquinolines, which are compounds that are formed as a result of this reaction [18].…”