Conformation and metabolism of (+)-(2Z,4E)-trans-1',4'-dihydroxy-.GAMMA.-ionylideneacetic acid, a biosyn-thetic intermediate of (+)-abscisic acid in Cercospora cruenta.

Abstract

The stereochemistry of (+)-(2Z, 4E)-trans-r, 4'-dihydroxy-γ-ionylideneacetic acid, a major metabolite from Cercospora cruenta, a fungus found to produce (+)-abscisic acid, was reexamined as to its 1H-1H-Cosy and Noesy 2D-NMR spectra, and it was proved to have a chair conformation with an axial pentadienoate moiety. Further, the metabolism of (+)-[14C]-1'4'-dihydroxy-γ-ionylideneacetic acid in tomato plants suggested the possibility of it being a biosynthetic intermediate of ABA in plants.