Duarte Lucienir Pains, Silva de Miranda Roqueline Rodrigues, Rodrigues Salomão Bento Vasconcelos, de Fátima Silva Grácia Divina, Vieira Filho Sidney Augusto, Knupp Vagner Fernandes
NEPLAM - Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil.
Molecules. 2009 Feb 4;14(2):598-607. doi: 10.3390/molecules14020598.
Friedelin (1), 3beta-friedelinol (2), 28-hydroxyfriedelin (3), 16alpha-hydroxyfriedelin (4), 30-hydroxyfriedelin (5) and 16alpha,28-dihydroxyfriedelin (6) were isolated through fractionation of the hexane extract obtained from branches of Salacia elliptica. After a week in CDCl(3) solution, 16alpha-hydroxyfriedelin (4) reacted turning into 3-oxo-16-methylfriedel-16-ene (7). This is the first report of a dehydration followed by a Nametkin rearrangement of a pentacyclic triterpene in CDCl(3) solution occurring in the NMR tube. These seven pentacyclic triterpenes was identified through NMR spectroscopy and the stereochemistry of compound 4 and 7 was established by 2D NMR (NOESY) spectroscopy and mass spectrometry (GC-MS). It is also the first time that all the (13)C-NMR and 2D NMR spectral data are reported for compounds 4 and 7.
从椭圆叶刺蒴麻树枝的己烷提取物中通过分馏分离出了蛇麻脂醇（1）、3β - 蛇麻脂醇（2）、28 - 羟基蛇麻脂醇（3）、16α - 羟基蛇麻脂醇（4）、30 - 羟基蛇麻脂醇（5）和16α,28 - 二羟基蛇麻脂醇（6）。在CDCl₃溶液中放置一周后，16α - 羟基蛇麻脂醇（4）发生反应，转变为3 - 氧代 - 16 - 甲基 - 16 - 烯基 - 赖百当（7）。这是首次报道在核磁共振管中的CDCl₃溶液中，五环三萜发生脱水反应后接着进行Nametkin重排。通过核磁共振光谱鉴定了这七种五环三萜，化合物4和7的立体化学通过二维核磁共振（NOESY）光谱和质谱（GC - MS）确定。这也是首次报道化合物4和7的所有¹³C - NMR和二维核磁共振光谱数据。
