BIOCHEMISTRY OF THE USTILAGINALES: IV. THE CONFIGURATIONS OF SOME β–HYDROXYACIDS AND THE BIOREDUCTION OF β–KETOACIDS

Abstract

The phytochemical reduction of the β-keto-n-caproic and β-keto-n-caprylic acids yielded the corresponding D-β-hydroxyacids. This observation is contrasted to bioreduction of β-ketobutyric acid to L-β-hydroxybutyric acid. The basis for the assignment of the above configurations is discussed. L-α-Hydroxy-n-valeramide was reduced with lithium aluminium hydride and the product was acetylated to yield L-1-acetamido-2-acetoxypentane. The enantiomorphic form of the latter compound was obtained through the Curtius degradation of D-β-hydroxy -n-caprohydrazide. The configurations assigned to the β-hydroxy-n-caprylic acids are based on the Levene–Marker Rule for the optical rotations of homologous compounds. The β-hydroxy-n-caproic and β-hydroxy-n-caprylic acids derived from ustilagic acid were thus shown to belong to the L-series. The use of infrared spectroscopy in configurational correlations is discussed and the infrared spectra of L-β-hydroxybutyrhydrazide, L-β-hydroxy-n-caprohydrazide, L- and DL-β-hydroxy-n-caprylhydrazides and D-, L-, and DL-1-acetamido-2-acetoxypentane are given.