Purines, pyrimidines, and imidazoles. Part XXVIII. Syntheses of 9-β-D-ribofuranosylzeatin 5′-phosphate, a naturally occurring adenylic acid derivative with plant cell-division promoting activity, and a new synthesis of 6-chloro-9-β-D-ribofuranosylpurine 5′-phosphate

Abstract

9-β-D-Ribofuranosylzeatin 5′-phosphate has been synthesised (a) by the reaction of 6-chloro-9-(2′,3′-O-isopropylidene-β-D-ribofuranosyl) purine with trans-4-amino-2-methylbut-2-en-1-ol and triethylamine, phosphorylation of the resulting isopropylidene zeatin riboside with pyrophosphoryl chloride, and removal of the protecting group by mild acid hydrolysis, and (b) by the reaction of 6-chloro-9-β-D-ribofuranosylpurine 5′-phosphate with the trans-amino-2-en-1-ol in potassium hydrogen carbonate solution. The identity of the synthetic nucleotide with a naturally occurring zeatin ribonucleotide confirms the structure of the latter. A new and improved synthesis of the 6-chloro-9-β-D-ribofuranosylpurine 5′-phosphate by phosphorylation of 6-chloro-9-2′,3′-O-isopropylidene-β-D-ribofuranosylpurine with pyrophosphoryl chloride and removal of protecting groups under mild acid conditions is described.