The Structure–Reactivity–Chemoselectivity Relationship on the Reactions of 1-Unsubstituted Tautomeric 2-Pyridones with Benzyne

Abstract

The reactions of 2-pyridones with benzyne were investigated in order to gain some insight into the structure–reactivity–chemoselectivity relationship involved in the tautomeric systems. All reactions examined have resulted in the formation of Diels-Alder and Michael-type adducts. It has been shown that the Diels-Alder reactivities were well correlated with the HOMO energy levels of the 2-pyridone form and the yields of the Michael-type adduct were closely associated with the tautomeric equilibria. In summary, the chemoselectivities of 2-pyridones in the reaction with benzyne were largely affected by the tautomeric properties.

Catalytic Hydroprocessing of Chloropyridinols

“…Thus, in the pyridine solvent used in this work the pyridone should be the preferred dechlorination product of 6-chloro-2hydroxypyridine. The pyridone forms a dimer, however, making it difficult to detect by gas chromatography (Kuzuya et al, 1984(Kuzuya et al, ,1985. The unusual activation energies of the reactants producing 3-hydroxypyridine may be due to the formation of zwitterions as shown in Figure 6 (Dyumaev and Smirnov, 1975).…”

Imidazole: Synthesis, Functionalization and Physicochemical Properties of a Privileged Structure in Medicinal Chemistry

“…The tautomer ratio observed in the 4(5)-nitroimidazole 10 derivative is approximately 400:1 for 4-nitroimidazole [ 9 ]. Reports in the literature suggest a relationship between tautomers 1.4 and 1.5 in the following proportion: log ([1.4]/[1.5]) = 4 × σ m [ 17 , 18 ]. However, for any substituent, whether electron withdrawing (EWG) or electron donor (EDG), the 1,4 tautomer predominates since the meta substituent constant (σ m ) is governed by inductive effects (σ m = 0.71, 0.37 and 0.10 for -NO 2 , -Br and -OCH 3 , respectively) [ 17 ].…”