A New Ent -Kaurane from the Roots of Lasianthaea aurea

A known kaurenoic acid (1), together with a new kaurane derivative named 3α-isobutyryloxykaurenoic acid (2), was isolated from the roots of Lasianthaea aurea, a plant endemic to Mexico. The compounds were characterized using their physical and spectroscopic data. In order to verify the structure and absolute configuration of 2, the derived methyl ester 3, obtained after diazomethane treatment, was subjected to single-crystal X-ray diffraction analysis, whose Flack and Hooft parameter calculations evidenced that the new natural product is an ent-kaurane derivative.