I₂-Catalyzed Three-Component Consecutive Reaction for the Synthesis of 3-Aroylimidazo[1,2-a]-N-Heterocycles

Abstract

A convenient one-pot, three-component reaction has been developed for the synthesis of 3-aroylimidazo­[1,2-a]-N-heterocycles from aryl ketones and 2-amino-N-heterocycles using dimethyl sulfoxide as a methylene donor. The reaction proceeds smoothly catalyzed by I2 in the presence of K2S2O8 and affords the desired products in moderate to good yields. This protocol offers significant superiority in accessing biologically active 3-aroylimidazo­[1,2-a]-N-heterocycles with various substitution patterns.

Iodine and DMSO as Surrogate of Hazardous Metal and Non‐Metal Reagents in Organic Synthesis

“…The valuable bioactivity of molecules are significantly observed in imidazopyridine scaffolds, [59–61] which motivated the researchers to seek the efficient methods for their synthesis. The synthesis of imidazopyridines has been achieved using SOCl 2 as a source of chlorine in the presence of H 2 SO 4 (Scheme 5 (b)) [62] and potassium sulfate in the presence of NaOAc supported by iodine in DMSO (Scheme 5 (d)) [63] . The use of catalytic amounts of flavin and iodine also helped to achieve this task (Scheme 5 (a)) [64] .…”

A Review on Molecular Iodine Catalyzed/Mediated Multicomponent Reactions

“…Zhang et al [21] . reported an iodine catalyzed three‐component reaction of 2‐aminopyridines, aryl ketones and DMSO in presence of K 2 S 2 O 8 giving 2‐aroylimidazo[1,2‐ a ]pyridine 12 in moderated to good yields (Scheme 3).…”

Synthesis of Substituted Pyrimido[1,2‐b]indazoles through (3+2+1) Cyclization of 3‐Aminoindazoles, Ketones, and N,N‐Dimethylaminoethanol as One‐Carbon Synthon

“…1). [17b,22] The reaction of acetophenone (2 a) with DMEA gave the corresponding α,β-enone (B) [22][23] in trace amount only (Scheme 3, eq. 2).…”