Pyridones, acidity regioselectivity

FMO calculations using PM3-C1 were used to investigate the regioselectivities obtained by the photochemical reactions between 2-pyridone and pcnta-2,4-dienoate.46 The hard and soft acid-base principle has been successfully used to predict product formation in Patemo-Buchi reactions.47 The 2 + 2-photo-cycloaddition of homobenz-valene with methyl phenylglyoxylate, benzyl, benzophenone, and 1,4-benzoquinone produced the corresponding Patemo-Buchi products.48 The photo-cycloaddition of acrylonitrile to 5-substituted adamantan-2-ones produces anti- and svn-oxetanes in similar ratios irrespective of the nature of the 5-substituent49... 

Substitutions usually proceed via attack on the neutral pyridone, but in very strong acid, where there is almost complete 0-protonation, 4-pyridone undergoes a slower nitration, via attack on the salt, but with the same regioselectivity. ... 

Deprotonation. Organolithium species are obtained from l-alkoxy-3-phenylseleno-1-alkenes (subsequent regioselective alkylation occurs at C-3), selenoamides, and selenono-thioesters. When those derived from oi,p-unsaturated acids condense with nitriles 2-pyridones are obtained. ... 

Pyridine-iV-oxides form stable 1 1-complexes with Lewis acids. The SbCl5 complexes 82, on thermolysis followed by hydrolysis, yield 2-pyridones by a regioselective transfer of oxygen to the a-position via 83. 

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