which are key intermediates in this approach, are obtained from enantiopure endo-tricyclo[5.2.1.02,6]decadienones (+)- and (+)- in 6 and 8 steps, respectively. Crucial steps are the reductive epoxy ring opening in compounds (+)- and to give the corresponding diols (+)- and , and the thermal cycloreversion of tricyclodecenones (+)- and , using the technique of flashvacuum thermolysis (FVT). The synthesis