Synthesis of Pyrimidine- and Quinazoline-Fused Benzimidazole-4,7-diones Using Combinatorial Cyclocondensation and Oxidation

Abstract

β-Bromo-α,β-unsaturated aldehydes and 2-bromobenzaldehydes react with 4,7-dimethoxy-1 H -benzo[ d ]imidazole-2-amine by microwave irradiation in dimethylformamide in the presence of a base to give the corresponding dimethoxy-substituted benzo[4,5]imidazo[1,2- a ]pyrimidines and benzo[4,5]imidazo[1,2- a ]quinazolines, respectively, in moderate to good yields. Oxidation of such N-fused hybrid scaffolds by aqueous ceric ammonium nitrate affords pyrimidine- and quinazoline-fused benzimidazole-4,7-diones in high yields.

One‐Pot Synthesis of Benzo[4,5]imidazo[1,2‐a]pyrimidin‐2‐ones Using a Hybrid Catalyst Supported on Magnetic Nanoparticles in Green Solvents

“… [23] Benzimidazopyrimidines have also been reported as pyrimidobenzimidazoles in literature. [ 23 , 24 , 25 ] They have widely biological properties such as antibacterial, [26] antiviral, [27] antifungal, [28] antiulcer, [29] anti‐HIV, [30] anticancer,[ 31 , 32 ] antiproliferative [33] and anti‐inflammatory [34] activities. For treatment of Alzheimer disease, some of these compounds have been applied as allosteric enhancer of acetylcholine affinity at muscarinic M 3 receptor, [35] imaging agent for detecting neurological disorders [36] and protection against amyloid β associated neurotoxicity.…”

“…Benzimidazo[1,2‐ a ]pyrimidines are an important category of N ‐fused heterocycles containing pyrimidine and benzimidazole rings [23] . Benzimidazopyrimidines have also been reported as pyrimidobenzimidazoles in literature [23–25] .…”

“…[21,22] Benzimidazo [1,2-a]pyrimidines are an important category of N-fused heterocycles containing pyrimidine and benzimidazole rings. [23] Benzimidazopyrimidines have also been reported as pyrimidobenzimidazoles in literature. [23][24][25] They have widely biological properties such as antibacterial, [26] antiviral, [27] antifungal, [28] antiulcer, [29] anti-HIV, [30] anticancer, [31,32] antiproliferative [33] and anti-inflammatory [34] activities.…”

Copper‐Catalyzed Synthesis of Trinuclear N‐Fused Hybrid Scaffolds by Double C(sp2)–N Bond Formation between 2‐(2‐Bromoaryl)indoles and 2‐Aminoazoles

“…No significant change of the yield of 3a was observed with prolonging the reaction time and higher molar ratio of [2a]/[1a] (Table 1, entries 4 and 5). Performing the reaction using other bases such as Cs 2 CO 3 , K 2 CO 3 , KO t Bu, NaO t Bu, NaOAc, and CsF under the employed conditions resulted in lower yields of 3a with incomplete conversion of 1a in some cases except for Cs 2 CO 3 , which showed an activity similar to that of K 3 PO 4 ( Table 1, entries [6][7][8][9][10][11]. Further addition of ligands such as L-proline and 1,10-phenanthroline resulted in no significant change of 3a yield ( Table 1, entries 12 and 13).…”

“…In the cases of 2b-2d, the products were produced as isomeric mixtures (1:1.7 for 3b and 3b′; 1:0.9 for 3c and 3c′; 1:1 for 3d and 3d′). [10] The isomeric ratios were calculated by the intensity of the clearly separated protons in 1 H NMR spectra (see Supporting Information for 1 H and 13 C NMR spectra). The reaction of readily available 2-(2-bromophenyl)indoles 1b-1e having straight and branched alkyl chains at indole moiety (R 1 ) with 2a also produced the corresponding trinuclear N-fused hybrid scaffolds 3g-3j irrespective of the identity of such alkyl substituents.…”