Many species of the family Ericaceae, such as the plants belonging to the genera Pieris, Rhododendron, Lyonia, Kalmia, and Leucothoe, are usually rich in grayanane-type diterpenoids with a 5/7/6/5 ring system, which is responsible for the toxicity of these species [1, 2]. Recently, a series of novel highly acylated diterpenoids with specific 3,4-secograyanane skeleton have been reported from Rh...