PREPARATION AND STRUCTURE-ACTIVITY-RELATIONSHIPS OF 4-SUBSTITUTED AMINO-2-METHYLPYRIDO[3,4-D]PYRIMIDINES AS CYTOKININ ANALOGS

Various 4-substituted amino derivatives of 2-methylpyrido[3,4-d]pyrimi dine were prepared to investigate their structure-cytokinin activity r elationships. Both an Amaranthus betacyanin and a lettuce seed germina tion bioassay revealed that most anilino and some alkylamino derivativ es were active, whereas benzylamino derivatives were inactive, indicat ing that the new cytokinin analogs differ from N-6-adenines in their s ubstituent effects on the activity. The most active was a m-fluoroanil ino derivative, which was as potent as N-6-benzyladenine in a tobacco callus bioassay. 2-Alkyl substituents smaller or larger than a methyl group reduced the activity.