The Stereochemistry of the Conversion of D and L 1,2-Propanediols to Propionaldehyde
B. Zagalak 1, Perry A. Frey 1, G. L. Karabatsos 1, and Robert H. Abeles 1
From the
1 From the Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02154, and the Department of Chemistry, Michigan State University, East Lansing, Michigan
When D-1,2-propanediol is converted to propionaldehyde in the presence of dioldehydrase and dimethylbenzimidazolylcobamide coenzyme, 1 of 2 C-1 hydrogens of the substrate is stereospecifically transferred to position C-2. The hydrogen transferred is the hydrogen introduced into D-1,2-propanediol by horse liver alcohol dehydrogenase when D-lactaldehyde is reduced to D-1,2-propanediol. When L-1,2-propanediol reacts, the other C-1 hydrogen exclusively is transferred. The displacement of the secondary hydroxyl group of propanediol by hydrogen, which takes place when D- or L-1,2-propanediol is converted to propionaldehyde, occurs with inversion of configuration at C-2. These results suggest that the removal of the secondary hydroxyl group may proceed through a displacement reaction in which the hydride functions as displacing nucleophile.
It was also shown that the reduction of D- and L-lactaldehyde with horse liver alcohol dehydrogenase and
-deuterated reduced diphosphopyridine nucleotide leads to D- and L-propanediol of identical configuration at C-1. Therefore, the stereochemical course of the reduction by horse liver alcohol dehydrogenase is not influenced by the configuration of the carbon adjacent to the center which is reduced.
Submitted on December 20, 1965