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The reaction of ecdysteroids (20-hydroxyecdysone and its acetonides) with lithium in liquid ammonia gave novel analogs with an oxetane 9α,14α-oxacycle in the steroid skeleton. In aqueous alcohol solution the 9,14-oxa analogs rearrange to the more stable 9α,13α−oxa analogs through a 1,2-migration of the 18-Me group from the C-13 to the C-14 atom.Although widely used in the chemistry of steroids [1, 2] for the selective reduction of a double bond in conjugated enones, a reaction with alkali metals in liquid ammonia has been little studied amongst the series of ecdysteroids. It is only known that the reaction of 20-hydroxyecdysone diacetonide with lithium in liquid ammonia solution gives a 14α-hydroperoxy derivative rather than the corresponding 7,8-dihydro analog [3].We have found that the action of a solution of lithium in liquid ammonia on the ecdysteroids 20-hydroxyecdysone (1), its 2,3:20,22 diacetonide (2), and the 20,22-acetonide (3) and 2,3-acetonide (4) and subsequent treatment of the reaction mixture with NH 4 Cl gives the corresponding 14α-hydroperoxides 5-8 together with the previously unknown 9α,14α-oxa derivatives 9-12 which are analogs of ecdysteroids with an oxetane ring in the steroid skeleton (Scheme 1). In the case of compound 1 the corresponding oxetane 9 and 14α-hydroperoxide 5 are formed in approximately equimolar amounts while the acetonides 2 and 3 are primarily converted to the corresponding oxetanes 10 and 11. For the 2,3-acetonide 4 the oxetane formed 12 is less stable than oxetanes 9-11 and elution of reaction products (SiO 2 , MeOH/CHCl 3 , 1:50) gave a mixture of the oxetane 12 and its isomerization product 19 as well as a mixture of the 14α-hydroperoxide 12 and starting material 4. Repeated chromatography (SiO 2 , MeOH/CHCl 3 ) of a mixture of compounds 12 and 19 gave the individual forms of the transformation products of oxetane 12, i.e. compounds 15 and 19.

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Steroids U 0300Unexpected Formation of an Oxetane Cycle by Oxidation of Diacetonide of 20-Hydroxyecdysone with Oxygen in an Alkaline Medium. -Reduction of title compound (I) and subsequent evaporation of ammonia on air leads to formation of oxetane (II) and hydroperoxide (III). On evaporation of ammonia in argon, cholestenone (IV) is formed. The reaction mechanisms are discussed. -(ODINOKOV*, V. N.; GALYAUTDINOV, I. V.; IBRAGIMOVA, A. S.; VESKINA, N. A.; KHALILOV, L. M.; DOLGUSHIN, F. M.; STARIKOVA, Z. A.; Mendeleev Commun. 18 (2008) 5, 291-293; Inst. Petrochem. Catal., Bashkortostan Rep. Acad. Sci., Ufa 450075, Russia; Eng.) -R. Langenstrassen