Concise, improved procedure for the synthesis of brassinolide and some novel side-chain analogues

摘要

Brassinolide (1) is a plant growth promoter that was first isolated in 1979 by workers at the U.S. Department of Agriculture. It exhibits activity at the nanogram/ individual plant level and is thus active at concentrations several orders of magnitude lower than other known classes of plant growth promoters. Brassinolide and related brassinosteriods have attracted considerable at- tention because of reports that they significantly increase the yields of several types of commercially important crops, even at exceptionally low dosage levels.