Total synthesis of natural (-)-ptaquilosin, the aglycon of a potent bracken carcinogen ptaquiloside and the (+)-enantiomer, and their DNA cleaving activities
The totalsynthesis of natural (-)-ptaquilosin (2) the aglycon of a potentcarcinogenptaquiloside (1) from bracken fern and its (+)-enantiomer (2) has been achieved starting with (+)-dimenthyl (1R,2R)-cyclopentane-1,2-dicarboxylate. The synthesis proceeds in 20 steps (2.9% overall yield). As the DNA cleaving activities, dienone 4 prepared from natural(-) ptaquilosin (2) was shown to be more efficient