Syntheses of Dexamethasone Conjugates of the Phytohormones Gibberellin A3 and 24-Epicastasterone

The syntheses of N -[10-(9α-fluoro-11β,17α-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carboxamido)decyl]gibberellamide ( 7 ) and 6-[({ N -[10-(9α-fluoro-11β,17α-dihydroxy- 16α-methyl-3-oxoandrosta-1,4-diene-17β-carboxamido)decyl]carbamoyl}methoxy)imino]-24-epicastasterone ( 10 ) are described. [(Benzotriazol-1-yl)oxy]bis(pyrrolidin-1-yl)methylium hexafluorophosphate (HBPyU) was used as the coupling agent for the reaction of gibberellic acid as well as of 24-epicastasterone- O -(carboxymethyl)oxime with N -(10-aminodecyl)- 9α-fluoro-11β,17α-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carboxamide ( 4 ). The gibberellic acid conjugate 7 was also synthesised by the coupling of succinimidyl gibberellate 6 with amine 4 .