Abstract
A simple, green, and efficient approach was used to synthesize 3,4-dihydropyrimidines derivatives. We showed that the application of the planetary ball milling method with a ball-to-reagent weight ratio of 8 for the Biginelli reaction provides 3,4-dihydropyrimidines derivatives with excellent yields (>98%) in a short reaction time from the one-pot, three-component condensation of aldehydes, ethyl acetoacetate, and urea (or thiourea).
Highlights
The development of new efficient methods to synthesize organic heterocycles that are both economical and eco-friendly presents a great challenge for the scientific community.Solvent-free reactions are highly significant from both economical and synthetic points of view.These kinds of reactions ensure an essential facet of green chemistry to reduce the risks to humans and the environment.Multicomponent reactions (MCRs) have gained importance because of their efficiency and effectiveness as a method for one-pot synthesis of a wide range of heterocycles [1,2,3,4,5,6]
Mal et al [41] showed that the 3,4-dihydropyrimidines can be accessed in two steps under ball milling through a combination of a catalytic amount of potassium bromide (KBr), oxone and TEMPO (2,2,6,6-Tetramethyl-1-piperidinyloxy)
We present an efficient one-pot, three-component solvent-free and catalyst-free approach to synthesize 3,4-dihydropyrimidine derivatives by direct condensation of equimolar quantities of benzaldehyde derivatives, ethyl acetoacetate, and urea/thiourea in a simple planetary ball mill at 750 rpm without adding any solvent or catalyst (Scheme 1)
Summary
The development of new efficient methods to synthesize organic heterocycles that are both economical and eco-friendly presents a great challenge for the scientific community. Solvent-free reactions are highly significant from both economical and synthetic points of view. These kinds of reactions ensure an essential facet of green chemistry to reduce the risks to humans and the environment. Multicomponent reactions (MCRs) have gained importance because of their efficiency and effectiveness as a method for one-pot synthesis of a wide range of heterocycles [1,2,3,4,5,6]. The 3,4-dihydropyrimidine and its derivatives are highly significant because they generally show diverse medicinal properties, such as calcium channel blockers, antihypertensive and anti-inflammatory agents, and α 1-a antagonists [8,9,10,11].
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