Aqueous phase synthesis of bridgehead azaheterocycles in the presence of β-cyclodextrin

Abstract

A simple and expeditious aqueous phase reaction of various α-bromoketones with 2-aminopyridine, 2-aminopyrimidine, 2-aminopyrazine, and their derivatives, and 2-aminobezothiazole in the presence of β-cyclodextrin has been demonstrated to furnish bridgehead azaheterocycles 5a-j, 7a-e, 9a-d, 12a, 12b and benzo [d]imidazo[2,1-b]thiazoles 11a-c respectively, in good to excellent yields.

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

“…Meng et al have used copper supported on manganese oxide-based octahedral molecular sieves OMS-2 (CuO x /OMS-2) as a heterogeneous catalytic system for a tandem synthesis of 3-iodoimidazo[1,2- a ]pyridines (Scheme 35) [120]. The synthesis was similar to that reported by Kumar and co-workers with the difference of a heterogeneous catalytic system and iodination of the product [121]. Molecular iodine was used as an iodinating agent in the reaction.…”

Recent advances in development of imidazo[1,2-a]pyrazines: synthesis, reactivity and their biological applications

“…The cavities of the cyclic oligosaccharides act as catalysts based on supramolecular catalysis, which leads to complex formation between phenacyl bromide and the cyclodextrin cavity, resulting in the formation of 101 (Scheme 30). 74 Kettle and coworkers reported the synthesis of 5,6-disubstituted imidazo[1,2-a]pyrazine. 2-Amino-5-bromo-6-chloropyrazine was treated with boronic acid coupling partners to provide the C5-substituted intermediate 102, followed by a second successive Suzuki coupling at the C6-position to afford 103.…”

Deep Eutectic Solvent‐Mediated Regioselective Synthesis of Imidazoheterocycles

“…[ 15–18 ] The common methods for the preparation include coupling of 2‐halocarbonyls with 2‐aminopyridine derivatives. [ 19–22 ] The copper‐catalyzed multicomponent reaction of 2‐aminopyridine with acetylene and aldehyde has also been reported. [ 10 ] Many of the reported procedures involve harsh reaction conditions, toxic and expensive reagents, long reaction time, and non‐recyclable catalysts, etc., which need the development of an economical, simple, more efficient, and eco‐friendly chemical process.…”

“…[ 23,24 ] The choline chloride‐based deep eutectic mixtures have been explored successfully in several organic transformations and catalysis. [ 22,23,25–30 ] Herein, we report catalyst‐free, mild, deep eutectic solvent (choline chloride:urea) assisted rapid and regioselective synthesis of nitrogen bridgehead imidazoheterocycles in good to excellent yields.…”