A hydrocyl group was selectively introduced at the C-17 or C-6 position of grindelic acid (1a) and 3α-hydroxygrindelic acid (1b) via the 17- or 7β-bromo derivatives (6a, b or 9a, b) given respectively by bromination with Br2 or NBA. The 7β-hydroxy derivatives (17a, b) were obtained via the 8β-methyl-7-one derivatives (14a, b) by reduction with NaBH4. The 7α-hydroxy derivatives (18a, b) were obtained selectively from the 8, 9-en-7-one derivatives (15a, b) which contain a cleaved structure at the C-9 position.
通过分别给出的17-或7β-溴衍生物(6a,b或9a,b)在古二酸(1a)和3α-羟基古二酸(1b)的C-17或C-6位选择性地引入氢酰基通过与 Br2 或 NBA 溴化。 7β-羟基衍生物(17a,b)由8β-甲基-7-酮衍生物(14a,b)通过NaBH4还原得到。 7α-羟基衍生物(18a,b)是从在C-9位含有断裂结构的8,9-en-7-one衍生物(15a,b)选择性获得的。