LACTONES .2. SYNTHESIS OF ENANTIOMERIC PAIRS OF LACTONES WITH THE PINANE OR THE FENCHANE SYSTEM

Starting from (+)- and (-)-myrtenols, and via iodolactonization, the e nantiomerically pure tricyclic lactones, with pinane systems, were obt ained. In the course of an acidic lactonization of the gamma,delta-epo xy esters 6a and 6b, the rearrangement of the pinane system to that of the fenchane was observed. The absolute configurations of the newly f ormed chiral centres of the lactones 4b and 11b were established by X- Ray diffraction analyses.