Sonochemically assisted 2,3-dideoxygenation and skeletal rearrangement of ecdysteroid derivatives

Sonochemical 2,3-dideoxygenation of ecdysteroids with the Δ ²⁽³⁾-bond generation and activation of the C-C bonds of the steroid core in the poststerone derivatives, that causes the skeletal rearrangement have been carried out for the first time. Thus, the ultrasonically assisted reaction of 2,3-dimesyloxy derivatives of ecdysteroids with the NaI-Zn-DMF system gives rise to their 2,3-dideoxy-Δ²⁽³⁾-analogues with yields 70-92%. In the case of 2,3-dimesyloxypoststerone as the initial ecdysteroid substrate the reaction is accompanied by the activation of the allyl moiety and semipinacol rearrangement, resulting in the C¹³-C¹⁴ bond migration with C/D rings contraction/expansion and providing novel short chain (8R)-13(14 → 8)-abeo-isomer.