Volvalerenol A, a New Triterpenoid with a 12-Membered Ring from Valeriana hardwickii. - Wang, Peng-Cheng; Ran, Xin-Hui; Luo, Huai-Rong; Ma, Qing-Yun; Liu, Yu-Qing; Dai, Hao-Fu; Zhou, Jun; Zhao, You-Xing (Organic Letters, 2013)