The sidechain of (24R) - 24 - methyl - 25 - hydroxybrassinosteroid 13 has b
een synthesized in an overall yields of 10.9 % from methyl hyodeoxycholanat
e 3 in 10 steps with the introduction of the hydroxyl group to the 25 - C b
y KMnO4 and the improved Sharpless asymmetric dihydroxylation as the two ke
y steps.