Pyridine ring nucleophilic recyclizations

The rearrangement of 3-nitropyridinium salts to 3-nitropyrroles

“…[35][36][37] On the basis of data received, we supposed the possibility of rearrangement of 3-benzoylamino-5-nitropyridinium salts 3 to 2-acyl-4-nitropyrroles 4. This idea we confirmed by experiment.…”

Ring‐Transformation Graphs in Heterocyclic Chemistry

“…Since the classical work of Dimroth pi), this type of reactions received great attention from organic chemists and this area has been extensively studied and reviewed (see, for example, (22)(23)(24)(25)(26)(27)(28)). These reactions frequently lead to unexpected products, they often involve unusual mechanisms and sometimes they prove to be the only routes to the target heterocyclic structures.…”

“…Many of them have special names and one can easily recall the well-known examples of the Dimroth rearrangement of azoles (21-23) (eq. (a)), azines (22,24) (eq. (29)) and fused azoloazines (29,24,20), Cornforth (22,23) (eq.…”

“…(15)). Other examples of "named" ring transformations are the well-known Hafner (24,26) and Zinke-Konig (24) reactions, as well as the processes of pyrrole, furan and thiophen interconversions (eq. (ZO)), generally accepted in the Russian literature as Yur'ev reactions (19).…”

A Novel Ring Transformation of Pyridinium Salts as a Route to 4-Arylpyridines

“…[1,2] Historically, the first thoroughly studied reaction of this type was the ZinckeϪKönig reaction [3] -cleavage of the quaternized pyridine ring by aromatic amines to form glutacondialdehyde dianils. Subsequently, a large number of reactions with ring opening and ring transformation of pyridine derivatives induced by nucleophilic reagents have been discovered and studied.…”