Unstable 1,1,2-enetriols as (probable) intermediates in the decarboxylation of .alpha.,.beta.-diketo acids
作者:Hans Dahn、Gerhard Rotzler
DOI:10.1021/jo00009a029
日期:1991.4
During the acid hydrolyis of (hydrated) 4-aryl-2,3-diketobutyramide 2 (aryl = phenyl, o-chlorophenyl, p-methoxyphenyl), 3-aryllactic acid (5) is formed by rapid decarboxylation of the intermediate diketo acid (3). In the decarboxylation step, a further unstable intermediate is formed. The latter manifests itself by reducing 1 mol of added iodine during the hydrolysis-decarboxylation reaction, thereby forming 3-arylpyruvic acid (6), isolated instead of 5. Thus, the oxidation of the unstable intermediate by iodine is more rapid than its ketonization. It is formulated as an 1,1,2-enetriol (4), more probable than an alpha-hydroxyketene.