((Chloro-2 ethyl)-3 nitroso-3 ureido)-1' O-isopropylidene-2',3'-alpha et beta-D-ribofurannose Urea, N-(2-chloroethyl)-N'-(2,3-O-(1-methylethylidene)-alpha(and beta)-D-ribofuranosyl)-N-nitroso- YS5012400