SYNTHESIS AND BIOLOGICAL-ACTIVITY OF 28-HOMOBRASSINOLIDE AND ANALOGS

28-Homobrassinolide has been synthesized from stigmasterol in an overa ll yield of 21%. The biological activity of 28-homobrassinolide, brass inolide, 24-epiibrassinoide, 22S,23S,24-epibrassinolide, and 22S,23S,2 8-homobrassinolides have been compared in the soybean epicotyl elongat ion assay. All the steroids except 22S,23S,28-homobrassinolide exhibit ed a similar biological activity, but the latter compound was substant ially less active. There appears to be a correlation between biologica l activity and overall dimensions of the steroidal side chain.