The Absolute Configuration at C24 of the Ecdysteroids Dacrysterone, Pterosterone and Ponasterone C

Abstract

The shielding values in ¹³C N.M.R. spectra of the ecdysteroids dacrysterone, pterosterone, and ponasterone C have been assigned, together with those for the 20,22- and 22,24-benzylidene acetal derivatives of the latter. From the N.M.R. data the C24 configuration of dacrysterone is assigned as 24R, while the 24s configuration is assigned to pterosterone and ponasterone C.