A comparison between Suzuki cross‐coupling reaction and direct arylation in the synthesis of new antibacterial imidazo‐pyrazines/pyridazines

Abstract

Two efficient synthetic routes to preparation of 2,3‐diarylimidazo[1,2‐a]pyrazines and 2,3‐diarylimidazo[1,2‐b]pyridazines are described. The procedures involve a Suzuki cross‐coupling reaction and a palladium‐catalyzed direct arylation at position 3 and finally a comparative study is achieved. The antibacterial activities of the synthesized compounds in vitro were measured and the results showed that most products presented moderate to good antibacterial activities. Compounds 3a, 3c, 3j, 3k, 3l, and 3n revealed obvious potency against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli with minimum inhibitory concentration values of 32 μg/mL, which were better compared with the others.

Synthesis and characterization of a supported Pd complex on volcanic pumice laminates textured by cellulose for facilitating Suzuki–Miyaura cross-coupling reactions

“…Reportedly, Pd NPs have been successfully used in C-C coupling reactions in the composition form with other materials and in nano scale. 35 For instance, we have executed this approach by using poly 4-vinylpyridine polymeric substrate and iron oxide magnetic nanoparticles. 36 Biphenyls, as one of the most important pharmaceutical compounds are synthesized via C-C coupling approach.…”

“…Meanwhile, designing novel catalytic systems including Pd NPs has found great importance and attracted so much attentions because Pd plays a key role in C-C couplings. 35,41,42 In this regard, we intend to introduce a novel designed Pd-containing catalytic system for the convenient synthesis of biphenyl derivatives.…”

Synthesis and Functionalization of Imidazo[1,2‐b]Pyridazine by Means of Metal‐Catalyzed Cross‐Coupling Reactions

“…A comparison between Suzuki-Miyaura coupling reaction and direct arylation at position 3 of imidazo[1,2-b]pyridazines was recently performed by Salek Soltani et al. [117] under direct arylation conditions [bromobenzene 1 equiv, Pd-(OAc) 2 5 mol %, PPh 3 0.5 equiv, 1 equiv, K 2 CO 3 (3 equiv), DMA, 130°C, 24 h], provided the desired product 102 in 56 % isolated yield (Scheme 49). Authors have shown that the direct arylation proceeded in general with lower yields than the Suzuki-Miyaura pathway.…”