ASYMMETRIC DIHYDROXYLATION OF STACHYSTERONE-C - STEREOSELECTIVE SYNTHESIS OF 24-EPI-ABUTASTERONE

Stachysterone C was synthesized from 20-hydroxyecdysone (20-ECD). Shar pless asymmetric dihydroxylation of this rare ecdysteroid using osmium tetroxide and a chiral ligand afforded 24-epi-abutasterone, another r are ecdysteroid, and its C-24 epimer, abutasterone. High diastereomeri c excess of the former ecdysteroid was obtained when the chiral ligand s dihydroquinidine 1,4-phthalazinediyl diether and dihydroquinidine 2, 5-diphenyl-4,6-pyrimidinediyl diether were employed. The two C-24 epim eric ecdysteroids exhibited similar moulting hormone activity in the M usca bioassay. However, they were significantly less active than 20-EC D. (C) 1998 Elsevier Science Ltd. All rights reserved.