Ir-Catalyzed Biomimetic Photoisomerization of Cyclopropane in Lathyrane-Type Diterpenes.

An efficient Ir-catalyzed biomimetic method for photoisomerization of cyclopropane in lathyrane-type diterpenes is reported. Lathyrane diterpenes featuring the -fused cyclopropane (-) were successfully prepared from -cyclopropane lathyranes (-) in excellent yields by this stereochemical permutations strategy, which first verified the biogenesis relationship between the lathyrane isomers. Moreover, could further convert into another -isomer . The present work provides a convenient route for easy access of naturally rare 12()--cyclopropane lathyranes.