Phytoecdysones ofSilene praemixta. I. Silenosterone

In addition to known ecdysteroids (2-deoxy--ecdysone and 2-deoxyecdysterone) fromSilene praemixta (Caryophyllaceae) we have isolated new ones — premixisterone and selenosterone (I), C₂₇H₄₂O₇, mp 115–117°C (from MeOH), []_D²⁸ +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), []_D²⁷ +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 14,22R,25-trihydroxy-5-cholest-7-ene-3,6-dione. The IR, PMR, and mass spectra of (I) and (II) are presented.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 793–797, November–December, 1979.