| Abstract: | The structure of premixisterone (I) — a new ecdysteroid fromS. praemixta M. Pop. (Caryophyllaceae) — has been established. Compound (I) has the composition C27H44O5, mp 110–112°C (from C2H5OH + H2O), [α] D 24 0 ± 4° (c 0.85; MeOH), (lambda _{max }^{{text{C}}_{text{2}} {text{H}}_{text{5}} {text{OH}}}) 202 nm (log ? 3.35), ν max KBr 3415 cm?1 (OH), 1710 cm?1 (C=0), and does not contain the δ7-6-keto grouping that is characteristic of natural ecdysteroids. The acetylation of (I) with (CH3CO)2 in Py gave the amorphous 3,22-diacetylpremixisterone (II), C21H48O7. Compound (I) has the structure of 3β,14α,22R,25-tetrahydroxy-5β-cholest-8-en-6-one. The IR, PMR, and mass spectra of (I) and (II) are given. |
