SYNTHESES OF CIS-ZEATIN AND ITS 9-(2-DEOXY-BETA-D-RIBOFURANOSYL) DERIVATIVE - A NOVEL SYNTHETIC ROUTE TO THE SIDE-CHAIN AT C(6), AND CYTOKININ ACTIVITY

cis-Zeatin (3a) and its 9-(2-deoxy-beta-D-ribofuranosyl) derivative (3c) have been synthesized from N-[(1,1-dimethylethoxy)carbonyl]glycine methyl ester (5) in 5 steps by adopting the "alpha-amino aldehyde/olefination" technology. The new cis-zeatin derivative (3c), its trans isomer (1c), and known trans-zeatin 9-beta-D-riboside (1b) were tested for cytokinin activity in the stimulation of chlorophyll biosynthesis in etiolated cucumber cotyledons. The riboside lb turned out to be the most active cytokinin among them, while the deoxyribosides lc and 3c showed a marked decrease and a total loss, respectively, of cytokinin activity.