Multicomponent Tether Catalysis Synthesis of Highly Functionalized 4‑(Pyridin-2-ylmethyl)-2-aminopyrroles via Cascade Reaction Is Accompanied by Decarboxylation

A multicomponent
tether catalysis
protocol for the synthesis of 4-(pyridin-2-ylmethyl)-2-aminopyrroles
(PMAPs) was constructed by simply refluxing a mixture of ethyl 2-(pyridin-2-yl)­acetates 1 and various types of arylglyoxal monohydrates 2 and different heterocyclic ketene aminals 3 in EtOH
solvent. Based on this reaction, a series of highly functionalized
PMAPs were obtained through a novel cascade reaction accompanied by
a decarboxylation mechanism. As a result, the pyridin-2-ylmethyl was
successfully introduced in the target compounds, and a library of
PMAPs were easily constructed using the cascade reaction described
in this study. This protocol demonstrated that the most important
feature was the decarboxylation reaction of the 2-(pyridin-2-yl)­acetates 1, which can be used in the synthesis of pyridin-2-ylmethyl-substituted
heterocycles, including pyrroles, pyridines, quinolones, and other
heterocyclic compounds resembling those found in nature.