Stereospecific multiple isotopic labeling of benzyl alcohol.

Isotopically labeled enzymatic substrates and biological metabolites are useful for many mechanistic analyses, particularly the study of kinetic and equilibrium isotope effects, determining the stereospecificity of enzymes, and resolving metabolic pathways. Here, we present the one-pot synthesis, purification, and kinetic analysis of 7R-[(2) H]-phenyl-[(14) C]-benzyl alcohol. The procedure involves a chemoenzymatic synthesis that couples formate dehydrogenase to alcohol dehydrogenase with a catalytic amount of nicotinamide cofactor. The reaction goes to completion overnight, and the measurement of a competitive kinetic isotope effect on the enzymatic oxidation of the purified product identified no (1) H contamination. This measurement is very sensitive to such isotopic contamination and verified the high level of isotopic and enantiomeric purity yielded by the new synthetic procedure.