Purines, pyrimidines, and imidazoles. Part XXXI. Some reactions of the allylic group in the plant cell-division promoting factor, zeatin, and its nucleoside and nucleotide derivatives
Attempted diphosphorylation of 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9-(2′,3′-O-isopropylidene-β-D-ribofuranosyl) purine with 2-cyanoethyl phosphate and dicyclohexylcarbodi-imide in pyridine followed by removal of protecting groups gave 6-(3-methyl-4-pyridiniobut-trans-2-enylamino)-9-β-D-ribofuranosylpurine 5′-phosphate, which was hydrolysed by an alkaline phosphatase to the riboside and by acid to the aglycone. The latter compound was synthesised from zeatin and methanesulphonyl chloride in pyridine, and also by reaction of 6-(4-chloro-3-methylbut-trans-2-enylamino)purine, (prepared from zeatin and methanesulphonyl chloride in NN-dimethylformamide) or, less readily, O-p-tolylsulphonylzeatin (from zeatin and toluene-p-sulphonyl chloride) and pyridine. Structures assigned to the compounds were confirmed by u.v. absorption, 1H n.m.r., and mass spectroscopic studies. The related 3-carbamoyl-1-[2-methyl-4-(purin-6-ylamino)but-trans-2-enyl]pyridinium chloride was obtained in a similar manner and the quaternisation of pyridine by allyl alcohols including zeatin in the presence of 2-cyanoethyl phosphate and dicyclohexylcarbodi-imide was shown to be general.