(Z)-Methyl 3-Amino-2-cyano-5-((3R,4R)-4-methyl-3-(methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino)piperidin-1-yl)-5-oxopent-2-enoate can be obtained from 6-Chloro-7-deazapurine (C365175) which can be used as reactant/reagent in synthesis of nucleosides through direct glycosylation of nucleobases with 5-O-mono-protected or 5-modified ribose.