Purines. XLV. Syntheses and cytokinin activities of the cis isomers of (1'R)-1'-methylzeatin and its 9-.BETA.-D-ribofuranoside.

Abstract

(1'R)-1'-Methyl-cis-zeatin (2b) and its 9-β-D-ribofuranoside (4b) have been synthesized for the first time from D-alanine (5) in 7 steps. The new cis-zeatin derivatives 2b and 4b, together with known cis-zeatin (2a), were tested for cytokinin activity in the tobacco callus and the lettuce seed germination bioassays. In both bioassays, the cytokinin activity was found to follow the order 2a>2b>4b, indicating that 2b and 4b were less active than the corresponding trans isomers 1b and 3b (natural cytokinins from Pseudomonas syringae pv savastanoi), respectively.