From 1,3-Keto aldehydo -Acids and Carbonyl Compounds

1 From l,3-Keto(aldehydo)-Acids and Carbonyl Compounds 

The classical general method for constructing 2-pyrones is that based on the cyclising condensation of a 

The long known synthesis of coumaUc acid from treatment of malic acid with hot sulfuric acid illustrates this route decarbonylation produces formylacetic acid, in situ, which serves as both the 1,3-aldehydo-acid component and the second component. Decarboxylation of coumaUc acid gives access to 2-pyrone itself.  

Conjugate additions of enolates to alkynyl-ketones or to alkynyl-esters are further variations on the synthetic theme. 

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From 1,3-keto(aldehydo)-acids and carbonyl compounds... 

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