Medium-ring 1,5-dienes. Part IV. Reactions of germacra-1(10),4,7(11)-triene with singlet oxygen and with the triphenyl phosphite–ozone adduct

In the reaction of 1O2 with germacratriene the isopropylidene double bond is attacked ca. 9 times more rapidly than the endocyclic double bonds, in contrast to the results in epoxidation. The triphenyl phosphite–ozone adduct reacts primarily at the torsionally most strained double bond, in support of the view that an oxiranium intermediate is formed in the rate-determining step.