Three New Atisane Diterpenoids from Spiraea japonica

Three new atisane diterpenoids, spiratisanins A – C ( 1  –  3 , resp.), featuring a phenylacryloxyl substituted ent ‐atisane skeleton, were isolated from Spiraea japonica together with two known atisine diterpene alkaloids, spiramine A ( 4 ) and spiradine F ( 5 ). The structures of these new compounds were elucidated as (5 β ,7 α ,8 α ,9 β ,10 α ,12 α ,16 β )‐16‐hydroxyatisan‐7‐yl (2 E )‐3‐phenylprop‐2‐enoate ( 1 ), (5 β ,7 α ,8 α ,9 β ,10 α ,12 α ,16 α )‐16‐hydroxyatisan‐7‐yl (2 E )‐3‐phenylprop‐2‐enoate ( 2 ), and (5 β ,8 α ,9 β ,10 α ,12 α ,16 β )‐16‐hydroxyatisan‐20‐yl (2 E )‐3‐phenylprop‐2‐enoate ( 3 ) on the basis of spectroscopic analysis.