Synthetic Progress of Daphnane-type Diterpenoids
Liu,Rong;Feng,Jing;Liu,Bo;College of Chemistry,Sichuan University;
Daphnane diterpenoids usually embrace a 5/7/6-tricyclic ring system with poly-hydroxyl groups located at C3, C4, C5, C9, C13, C14, C20 and some special ones have a characteristic orthoester motif located at C9, C13, C14. The daphnane diterpenoids can be categorized into daphnetoxins, 12-hydroxydaphnetoxins, 1-alkyldaphnanes, resiniferonoids, genkwanines and rediocides, based on the oxygen containing functions at rings B and C, as well as the substitution pattern of the ring A. Besides, some daphniphyllum alkaloids are qualified with daphnane and seco-daphnane skeletons. Up to now, more than 100 daphnane diterpenoids have been isolated from Thymelaeaceae and Euphorbiaceae. Their structures have been determined on the basis of chemical correlation, NMR, X-ray diffraction, IR and other spectral analysis. The in-vitro and in-vivo experiments of these compounds have shown that they bear a wide range of biological activities including anti-HIV, anticancer, anti-leukemic, neurotrophic, pesticidal and cytotoxic effects. The biogenic hypothesis postulated that the daphnane-type and the tigliane type diterpenoids can be derived from a common intermediate, and that the tigliane-type can be transferred into the daphnane-type diterpenoids. There have been few papers on the total syntheses of daphnane diterpenoids owing to the synthetic challenges derived from their dense, highly oxygenated and polycyclic skeletons. However, numerous synthetic endeavors have been made in constructing core structures of daphnane diterpenoids based on various methodologies. In this paper, we focus on reviewing the synthetic efforts which have been made for daphnane diterpenoids, and we divide the main body of this paper into two parts, total syntheses and the related methodologies. The first part contains the asymmetric total synthesis of(+)-resiniferatoxin, the gateway synthesis of C6-C7-epi-yuanhuapin, and the biomimetic synthesis of(±)-methyl-homosecodaphniphyllate. The second part is classified according to the sequence of constructing the ABC core of daphnane diterpenoids, including the [X-BC-ABC] approach, the [X-AB-ABC] approach, the [AX-ABC] approach, the [CX-ABC] approach, the [A'B'C'-ABC] approach and the [X-ABC] approach.
【CateGory Index】： O629
【CateGory Index】： O629