conformation. Inspection of the NMR spectra of , compared to , shows a evident flattening of the butyrolactone ring and an axial orientation of the side-chain, which is a new type of this remote effect, with the 3-methyl trans to the side-chain. These special features arise from the steric interaction which would occur in the regular conformation between the 3-methyl and the substituents at C5. During