An alternative synthesis of deuterated cytokinins.

A novel synthesis of penta-deuterated 2-methylthiocytokinins, (+/-)-dihydrozeatin, and (+/-)-dihydrozeatin riboside is reported. penta-deuterated 2-methylthiocytokinins,2-methylthio-ribosyl-zeatin(I) and N6-isopentenyl-2-methylthioadenosine(II), were prepared by condensation of amines-d2 and 6-chloro-2-methylthio-9-beta-D-ribo-furanosylpurine-d3 which was derived from AICA-riboside. The deuterium contents of I and II were 95.75% and 98.27%, respectively. Racemic 4-hydroxy-3-methyl-l-butylamine-d5, which was prepared newly from gamma-butyrolactone, was condensed with 6-chloropurine and 6-chloro-9-beta-D-ribofuranosylpurine to give racemic dihydrozeatin (III) and dihydrozeatin riboside-d5 (IV). The deuterium contents were 97.82% and 97.23%, respectively.