Synthesis of sulfated brassinosteroids

- Benzylation is an effective way for partial protection of steroidal 22,23-diols.
- 2,3-Disulfate and four monosulfates of epibrassinolide were synthesized.
- Their solubility in water was much higher than those for the parent epibrassinolide.

A number of water soluble sulfates of 24-epibrassinolide including the 2α,3α-disulfate and all possible monosulfates were synthesized. The target compounds were isolated in crystalline form as the corresponding sodium salts. Pyridine-sulfur trioxide complex was used as sulfating agent followed by transformation of the resulting pyridinium salts into the sodium sulfates by treatment with NaOH. The control of the regioselectivity was achieved by an appropriate use of acetyl and benzyl protecting groups.

124