Analogs of the cytokinins trans-zeatin and benzylaminopurine have been prepared by Heck coupling on 6-vinylpurines or Sonogashira coupling on 6-halopurines as key-steps, and their cytokinin activity has been evaluated based on their ability to stimulate increased growth in radish cotyledons. (C) 1998 Elsevier Science Ltd. All rights reserved.