Abstract
The following phosphate derivatives of vitamine B_6 were prepared in crystalline form : pyridoxal-5-phosphate, pyridoxamine-5-phosphate, pyridoxine-5-phosphate and deoxypyridoxine-5-phosphate. Phosphorylation was accomplished by the reaction of pyridoxamine or isopropylidenepyridoxine or deoxypyridoxine with a mixture of phosphoric acid and phosphorus pentoxide. Pyridoxal-5-phosphate was obtained in 72% yield by the deaminative oxidation of pyridoxamine-5-phosphate with glyoxylic acid and copper or nickel salt which was the highest among several kinds of synthetic method.
