title: (E)-2-Hy-droxy-4-meth-oxy-3-(3-methyl-but-2-en-yl)-6-styryl-benzoic acid.
abstract: The title compound, C21H22O4, also known as cajanine, features an intra-molecular O-H⋯O hydrogen bond between the adjacent carb-oxy and hy-droxy groups. The benzene rings make an inter-planar angle of 175.4 (2)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers.
authors.affiliation: Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, People's Republic of China.
authors.forename: Xingyue
authors.initials: X
authors.lastname: Ji
authors.forename: Jie
authors.initials: J
authors.lastname: Jin
authors.forename: Guanghui
authors.initials: G
authors.lastname: Zheng
authors.forename: Zhuorong
authors.initials: Z
authors.lastname: Li