N-[Imino(methylthio)methyl]-carbamic Acid Phenylmethyl Ester is an intermediate in synthesizing 1-β-D-Ribofuranosyl-3-aminocarbonyl Guandinine (R415500), which is an impurity of 5-Azacytidine (A796000). 5-Azacytidine is a potent growth inhibitor and cytotoxic agent. 5-Azacytidine acts as a demethylating agent by inhibiting DNA methyltransferase.