Modified labdane diterpenes from Amphiachyris amoena

Two new modified labdane diterpenes, amoenolide L [1] and amoenolide M [2] with a 3-(p-hydroxyphenyl)propionate ester unit, were isolated from the above-ground parts of Amphiachyris amoena. Their stereochemical structures were assigned by spectral methods including uv, ir, fabms, and one- and two-dimensional high field 1H- and 13C-nmr. Properties of their acetate derivatives are also recorded.