5'-Chloro-5'-deoxy-2',3'-O-isopropylideneadenosine reacts with disodium salts of L-homocysteine, L-cysteine or 3-mercaptopropanoic acid in liquid ammonia to afford 2',3'-O-isopropylidene derivatives which are easily desalted by chromatography on octadecyl-silica column. On acid treatment, the high purity preparations of S-adenosyl-L-homocysteine, S-adenosyl-L-cysteine, and 5'-carboxyethylthio-5'-deoxyadenosine are obtained in respectable yields.