Chemical Synthesis of α-Formylphenylacetic Acid, the Postulated Precursor of Tropic Acid

Abstract

a-Formylphenylacetic Acid, Phenylmalonic Semialdehyde, Tropic Acid Biosynthesis a-Formylphenylacetic acid, the postulated immediate precursor of tropic acid, has been synthesized by deacetalization of a-diethoxymethylphenylacetic acid in the presence of silica gel. The compound was reasonably stable in organic solution. In aqueous media, however, a pronounced lability of this semialdehyde was observed at various pH-values (t/2 = 4.5 min at pH 7.4). It is thus very unlikely that this compound can be employed successfully in biosynthetic studies.

Phenyllactic acid but not tropic acid is an intermediate in the biosynthesis of tropane alkaloids in Datura and Brugmansia transformed root cultures

“…Putative pathways involving free cinnamic acid (Leete and Kirven 1974;Evans and Woolley 1976;Leete 1983), its epoxide (Leete and Kirven 1974), 3-hydroxy-3-phenylpropanoic acid (Leete 1983) and 3-amino-2-phenylpropionic acid (Cox and O'Hagan 1991) have been excluded. A further putative intermediate, ~-formylphenylacetic acid, is extremely unstable in aqueous solution, making it difficult to test the intermediacy of this compound (Gross et al 1981).…”