The synthesis of phosphor derivatives of ribosyl zeatin

Powdered sulfur was used for the conversion of the protected ribosyl zeatin phosphonate derivatives 2 and 3 into the corresponding thiophosphate 8 and 9, whereas 2,2-dipyridyldisulfide in the presence of methanol was used for the conversion of 2 and 3 into the corresponding methyl phosphates 6 and 7. After cleavage of the protecting groups of 2,3,6,7,8 and 9 under mild acidic condition the phosphor derivatives of ribosyl zeatin 1b-1g are obtained.