ON THE BEHAVIOR OF MONOLIGNOL GLUCOSIDES IN LIGNIN BIOSYNTHESIS .1. SYNTHESIS OF MONOLIGNOL GLUCOSIDES LABELED WITH H-2 AT THE HYDROXYMETHYL GROUP OF SIDE-CHAIN, AND POLYMERIZATION OF THE LABELED MONOLIGNOLS IN-VITRO

For selective labeling of specific structural units of protolignin in the plant cell wall, three kinds of precursor of lignin biosynthesis, p-glucocoumaryl alcohol, coniferin and syringin labeled with H-2 at th e hydroxymethyl group of side chain (gamma-position) were synthesized. The H-2 at gamma-position was retained during the dehydrogenative pol ymerization of labeled monolignol in vitro. On thioacidolysis, the pol ylignol labeled at side chain gamma-position with H-2 gave thioethers of monomeric degradation products which retained the H-2. These facts indicate that gamma-labeled monolignol glucosides are useful in tracer experiments on lignin biosynthesis.