Studies directed towards the preparation of probes for the photoaffinity labelling of gibberellin receptors

Model studies for the preparation of photoaffinity probes designed to explore the nature of gibberellin receptor sites have provided a wide range of gibberellin derivatives that should afford useful scaffolds incorporating auxiliary groups attached to C-2 and C-12. Methodology features the stereocontrolled opening of 2β,3β-epoxy gibberellins by attack on the lower face at C-2, while functionalization of C-12 was effected by the rhodium acetate-catalyzed CH insertion reaction of a 17-diazo ketone. Compounds were screened for bioactivity in growth and barley endosperm-based bioassays.