Daphnanes

Diterpenes from Euphorbiaceae are toxic to livestock, and so are daphnane and daphnetoxin, diterpenes from Daphne mezereum (Thymelaeaceae). Toxins fromRhododendron are diterpenes. 

Yoshida M, Feng W, Saijo N, Ikekawa T (1996) Antitumor activity of daphnane-type diterpene gnidimacrin isolated from Stellera diamaqasme L. Int ] Cancer 66 268-273... 

The Williams approach to bicyclo[5.4.0]undecane containing molecules such as the cyathins, striatins, dolastanes, clavularanes, grayanotoxins, tiglianes, and daphnanes also utilizes an oxidopyrylium cycloaddition to generate the ether constrained bicyclic (Scheme 4.81) (164). The object of the Williams study was to prepare the bicyclo[5.4.0]undecanes and investigate the regio- and stereocon-trolled oxidation of the substrate. 

Resiniferatoxin (RTX) is a daphnane diterpenoid contained in the irritant latex of some succulent African Euphorbias. Its total synthesis has been described as a 40 step asymmetric synthesis (Wender et al., 1997 see below), but for clinical use RTX isolated from Euphorbia resinifera. 

Daphnanes (C5 (C7 C6) include a variety of cytotoxic, irritant, inflammatory and toxic compounds from the Thymelaeaceae and the Euphorbiaceae. Of particular note are the highly inflammatory PKC activators resiniferatoxin and tinyatoxin from Euphorbia species (Euphorbiaceae) and thymeleatoxin from Thymeka hirsuta (Thymelaeaceae). While the nonester resiniferonol is inactive, the ester (X—CO—O—Y) resiniferatoxin is both an anti-nociceptive vanilloid receptor (capsaicin receptor) agonist and a PKC activator, as is the ester tinyatoxin. 

Daphnezomine L (48) was close structurally to a biogenetic intermediate between the secodaphnane and daphnane skeletons. 

A possibly biomimetic transformation of the secodaphnane to the daphnane skeleton with various Lewis acids has been investigated (Scheme 18,26) [73],... 

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