“…Compound 23,being devoid of both such multiple bonds and an electron-donating 2-substituent, was found to be inactive. ll,14 and 21 were exposed to the tobacco callus assay. Since they gave almost the same maximumyields as that of BA, they were new cytokinins;^-substituted derivatives ll, 14 and 21 were significantly more active than parent compound 6 (Fig.…”