Ecdysone, 20-hydroxy

The term ecdysteroid was originally defined as "all compounds structurally related to ecdysone" [4], However, Lafont and Horn [5] differentiated between true ecdysteroids and ecdysteroid-related compounds. True ecdysteroids possess a steroid nucleus with an A/B-cis-ring junction and a 14a-hydroxy-7-en-6-one chromophore, irrespective of their biological activity, while ecdysteroid-related compounds do not fulfil all these criteria. 

Scheme 3). A clone of cells from the midge Cbironomus tentans was found to be resistant to the effects of ecdysteroids because they metabolized 20-hydroxyecdysone rapidly. The initial oxidation product was 20,26-dihydroxyecdysone, but this was oxidized further to 20-hydroxy-26-oxo-ecdysone (21). This aldehyde (21) then formed a tautomeric equilibrium mixture of two cyclic hemiacetals (22) and (23), which were separable, isolated, and their structures determined (Scheme 3) with the use of acetonides (Section 4.03.3.6).32 These are the first examples of ecdysteroids with side-chain hemiacetals. Although 20,26-dihydroxyecdysterone still... 

Following a possible biosynthetic pathway to 3/8,14-dihydroxycholest-7-en-6-one (355), a precursor of ecdysones, 3/8-acetoxycholesta-5,7-diene (352)was isomerized to the 6,8(14)-diene (353) epoxidation and acidic hydrolysis then gave the mixed 6,14a-diols (354), which were oxidized by MnOa to give the required 14a-hydroxy-7-en-6-one system (355). Several cholest-7-en-6-one derivatives related to ecdysones, but lacking side-chain hydroxylation, have been prepared from cholesterol by efficient routes based largely on known individual steps. 

Sterols. A considerable amount of work was devoted to the study of backbone rearrangements. - While partial syntheses of an insect moulting hormone, ecdysone, were announced by several groups, evidence is accumulating on the widespread occurrence in natxire of its hydroxylated derivatives. This year saw the isolation of 20-hydroxy-ecdysone - - from silkworm (ecdysterone), crayfish - (crustecdysone), oak-silk moth, tobacco hornworm, and from plants such as Podocarpus nakaii, Podocarpus elatus, and Achyranthis. The ready isolation of insect-moulting hormones from plants in contrast to -the extremely poor... 

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