Sarcodonin

A total synthesis of the pyrazine alkaloid Botryllazine B from the red ascidian Botryllus leachi was accomplished, and a previously proposed structure was shown to be correct <04M333>. Also in the natural product arena, six new polyhydroxy-p-terphenyl pyrazinediol dioxide conjugates 98a-c and 99a-c related to sarcodonin were isolated from the fruiting bodies of the basidiomycete Sarcodon leucopus <04EJO592>. 

The cyathane diterpenoids have a characteristic 5-6-7 membered tricyclic skeleton. Piers et al. reported the synthesis of one of the cyathane diterpenoids, ( )-sarcodonin G (198) [58]. In this synthesis, a mixture of 196 and 197 (30 1) obtained from selenide 195 by oxidation, cleanly isomerized to give thermodynamically favoured 197 in the reaction with DBN in refluxing benzene (Scheme 7.45). 

Piers, E., Gilbert, M. and Cook, K.L. (2000) Total synthesis of the cyathane diterpenoid ( )-sarcodonin G. Organic Letters, 2, 1407-1410. 

C20H28O2. Mr 300.44, yellow syrup, [a]o +87.1° (CH3OH). Biogenetic close relatives are herical as well as sarcodonin and the striatals. C. from the monkey head mushroom (Hericium erinaceum) show anti-ischeraic activities (improvement of cerebral ischemia in rat model). 

The diterpene sarcodonin has been synthesized by the Piers group using a radical-initiated regioselective expansion promoted by Sm(II) (Scheme 47) [83]. 

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