22-Oxocholestanes as plant growth promoters

• 22-Oxocholestane derivatives are synthesized from steroidal sapogenins.
• The new side-chain is obtained in a four-step pathway from the spiroketal moiety.
• Plant growth promotion is given in Mexican rice cultivars.
• 22-Oxocholestanes are as active as homobrassinolide.

The spirostanic steroidal side-chain of diosgenin and hecogenin was modified to produce 22-oxocholestane derivatives. This type of side-chain was obtained in good yields through a straightforward four-step pathway. These compounds show potent brassinosteroid-like growth promoting activity evaluated via the rice lamina joint inclination bioassay. This is the first report of steroidal skeletons bearing the 22-oxocholestane side-chain and preserving the basic structure (A–D rings) from their corresponding parent compounds acting as plant growth promoters.

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