No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

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.

No abstract