Iridium-Salen-Catalyzed Synthesis of Spirocyclopropyl Lactones

Significance

There are several known methods for the construction of chiral 1,4-cylcoheptadienes. Of the reported methods only low to ­moderate yields and moderate enantioselectivities were observed. In this report Katsuki has expanded on his previous findings of iridium-salen-catalyzed cyclopropanation to furnish α-spirocyclopropyl lactones, which were later derivatized via a Cope rearrangement to give chiral 1,4-cycloheptadienes.