Cantharis beetle

Cantharidin 7 is the poison of the cantharis beetles, among them the Spanish fly, native to Southern Europe. Cantharidin is a skin irritant and vesicant. 

Animal products constitute 20% of homeopathic remedies and are collected from whole animals or their parts. Apis mellifica is prepared from the whole honey bee, Cantharis from the dried powder of the beetle, Cantharis vasicata, Sepia officinalis from the ink gland of the cuttle fish, Lachesis from the venom of the bush master snake and Tarantula hispanica from the poisonous Spanish spider (Cook, 1988). Lac caninum is prepared from dog s milk and Calcarea carbonica from oyster shell. 

Cantharidin (24) [31] represents the simplest known inhibitor of the ser-ine/threonine protein phosphatases 1 and 2A, and can be isolated from dried beetles (Cantharis vesycatoria). The simplest synthesis of 24 from furan and dimethylmaleic anhydride met with failure, even at pressures as high as 6.0 GPa either at rt or at temperatures of up to 350 °C, presumably due to the thermodynamic instability of the adduct at normal pressure, e.g., when pressure is released [32], However, if this reaction could be carried out in the presence of Pd/C and H2,24 might be obtained in one step. Nevertheless, high-pressure cycloaddition turned out to be very useful for the synthesis of cantharidin and its derivatives [31-33]. For instance, ( )-palasonin was synthesized from furan and citraconic anhydride (21) at 0.8 GPa for 138 h, followed by hydrogenation over Pd/C. Neither high temperatures nor... 

Cantharidin is obtained from cantharides, the dried beetle Cantharis vesicatoria ( = Lytta vesicatoria) (Meloidae) or other spp., containing not less than 0.6%, or from mylabris, the dried beetles Mylabris sidae = M. phalerata), M. cichorii and M. pustulata (Meloidae), containing not less than 1%,... 

Cantharides. Spanish fly blistering fly hlistering beetle Cantharis vesicatoria. Habit. Southern and Central Europe, mainly upon Oleaceae and Caprifotiaceae. Constit. 0.6-1% cantharidin, 10-15% fat resinous substances, acetic and uric acids. Powerful irritant, vesicant, rubefacient. Review Ude, Heeger, Pharm. Zentrulhatle 82, 193 (1941). 

Cantharidin is a powerfiil vesicant that can be isolated from dried beetles Cantharis vesicatoria, or Spanish fly ). Outlined here is the stereospecific synthesis of cantharidin reported by Gilbert Stork (Columbia University). Supply the missing reagents (a)-(n). 

Q 15. Explain why the following [4 + 2] cycloaddition reaction does not occur to produce cantharidin isolated from dried beetles Cantharis vesicatoria). 

Cantharidin a toxic agent, M, 196.21, m.p. 218°C, produced by the beetle Cantharis vesicatoria (Spanish fly, blistering beetle), native to southern and central Europe. C. is biosynthesized from mevalonic acid. Its use as an aphrodisiac has caused fatalities. 

This compound, an oxygen heterocycle, is the active principle in cantharis (also known as Spanish fly), a material isolated from certain dried beetles of the species Cantharis vesi-catoria and incorrectly thought by some to increase sexual desire. 

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