Three Component Reaction: An Efficient Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones and Thiones Using Heterogeneous Catalyst

Abstract

Fluoroboric acid supported on silica gel (HBF 4 -SiO 2 ) catalyzes efficiently the three component condensation of an aldehyde, a 1,3-dicarbonyl compound and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones and thiones in high yields. The ambient conditions, fast reaction rates, and excellent product yields are the important characteristics of this reaction.

Synthesis, crystal structure and antibacterial studies of dihydropyrimidines and their regioselectively oxidized products

“…It is known that a lot of protocols were developed for performing Biginelli reaction, leading to the synthesis of H 2 Py with high yields under “green” conditions and simple work-up procedure. Using catalyst types such as I 2 /MWI, 67 Yb(PFO) 3 , 68 TMSCl/CAN, 69 [Hmim]HSO 4 –NaNO 3 , 70 CAN, 71 GaI 3 , 72 HBF 4 –SiO 2 , 73 Sm(ClO 4 ) 3 , 74 H 3 PMo 12 O 40 , 75 La(OTf) 3 , 76 Sc(OTf) 3 , 77 In(OTf) 3 , 78 RuCl 3 , 79 MgCl 2 ·6H 2 O, 80 CeCl 3 ·7H 2 O, 81 acetic acid, NH 4 Cl 17 and others, 3–14 it was not possible to perform a Biginelli reaction on the basis of all used aldehyde scaffolds, urea and methylacetoacetate. In addition to this, performing the synthesis in microwave reactor becomes more popular over the conventional method, due to the fact that microwave method increases speed, reproducibility and scalability of the reaction.…”

Synthesis, crystal structure and antibacterial studies of 2,4,6-trimetoxybenzaldehyde based dihydropyrimidine derivatives

“…[Hmim]HSO4-NaNO3 [62], TMSCl/CAN [63], GaI3 [64], CAN [65], Sm(ClO4)3 [66], La(OTf)3 [67], RuCl3 [68], HBF4-SiO2 [69], H3PMo12O40 [70], Sc(OTf)3 [71], MgCl2×6H2O [72], In(OTf)3 [73] and NH4Cl [16] did not lead to the desired effect. Only improving the [74] procedure by performing the reaction in the presence of Cu(OTf)2 in microwave conditions allowed us to obtain targeted dihydropyrimidine with 80% yield.…”

Biginelli Reaction: Polymer Supported Catalytic Approaches

“…After work up and recrystallization, excellent yields of DHPMs were obtained. The recovered catalyst was recycled for five consecutive cycles with slight decrease in activity . The efficiency of HBF 4 –SiO 2 catalyst was compared with earlier reported catalysts; the described catalyst was found to be comparatively better.…”