Phytoecdysones ofSilene praemixta. I. Silenosterone

In addition to known ecdysteroids (2-deoxy-α-ecdysone and 2-deoxyecdysterone) fromSilene praemixta (Caryophyllaceae) we have isolated new ones — premixisterone and selenosterone (I), C₂₇H₄₂O₇, mp 115–117°C (from MeOH), [α] _D ²⁸ +86.9 ± 2° (c 0.92, MeOH), yield 0.003%. The acetylation of (I) with (CH₃CO)₂O in Py gave 22-acetyl-selenosterone (II), C₂₉H₄₄O₆, mp 210–212°C (MeOH-C₆H₁₄), [α] _D ²⁷ +45.5 ± 3° (c 0.16; MeOH). On the basis of physiocochemical and spectral characteristics it has been established that (I) has the structure of 14α,22R,25-trihydroxy-5β-cholest-7-ene-3,6-dione. The IR, PMR, and mass spectra of (I) and (II) are presented.