Synthesis of Novel 3,19-Dihydroxyjolkinolides and Related Derivatives Starting from Andrographolide

The jolkinolides are a series of naturally occurring ent-abietane diterpenes with potent antitumor activity, which have been isolated from the genus Euphorbia. We describe the first method for the total synthesis of 3,19-dihydroxyjolkinolide and its derivatives. The strategy for the synthesis of 3,19-dihydroxyjolkinolide A has 12 steps with an overall yield of 4.3%. The synthesized compounds were evaluated for their antitumor activity in nine kinds of tumor cell lines.