A new chemical synthesis of 2-amino-( N- d-ribofuranosyl)acetamide 5′-phosphate

Abstract

2-amino-( N- d-ribosyl)acetamide 5′-phosphate (GAR, 10) has been prepared in a readily scaled-up synthesis from 2,3- O-isopropylidene- d-ribofuranosylamine p-toluenesulfonate ( 3) by condensation with the mixed anhydride of N-(benzyloxy-carbonyl)glycine, followed by phosphorylation with 2-cyanoethyl phosphate and removal of the protecting groups. By varying the conditions, the α- 4 and the β- 5 anomers could be obtained and separated from each other. Anomerization occurs upon removing the O-isopropylidene group from either 7 or 8, so that the final compound ( 10) is an equimolar mixture of both anomers, of which only one is active toward GAR-transformylase.