PubMed · 4387248
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W H Toliver, C G Roach, R W Roundy, P E Hoffman. 1969. Liquid crystals.. https://pubmed.ncbi.nlm.nih.gov/4387248/
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4,5-Secocholestane (1a) and 4-methyl-4,5-secocholestane (1b) were synthesized from cholesterol (2) in five and seven steps, respectively. The key intermediate, 5-oxo-4,5-secocholestan-4-al (7) was reduced by the Clemmensen method to afford 1a. Meanwhile, 7 underwent selective Wittig reaction, Clemmensen reduction, and hydrogenation to give another target molecule, 1b. The structure of an unknown biomarker was shown to be different from the proposed 1a by gas chromatographic and mass spectrometric comparison.
13,17-Secodiacholestanes (6) were synthesized from cholesterol (1) in six steps. The key intermediates, (20R)- and (20S)-diacholest-13(17)-enes (3a and 3b), underwent ozonization and reduction to provide (20R)- and (20S)-13,17-secodiacholesta-13,17-dione (5a and 5b), respectively. On Clemmensen reduction, the diones (5a and 5b) yielded the target molecule 6. The structure of an unknown biomarker was shown to be different from the proposed 6 by gas chromatographic/mass spectrometric comparison.
Three new steroid sulfates--3 beta-hydroxy-5 alpha-cholestan-6 alpha-yl sulfate, 6 alpha-hydroxy-5 alpha-cholestan-3 beta-yl sulfate, and 5 alpha-cholestan-3 beta,6 alpha-diyl disulfate--were synthesized. For the syntheses of the key intermediates, 3 beta-hydroxy-5 alpha-cholestan-6 alpha-yl acetate and 6 alpha-hydroxy-5 alpha-cholestan-3 beta-yl acetate, selective protection of hydroxy groups in 5 alpha-cholestane-3 beta,6 alpha-diol was necessary. This problem was solved by using a combination of acetyl, tetrahydropyranyl, and methoxymethyl protective groups, which represents a new approach leading to these hydroxy acetates. Sulfated derivatives of 5 alpha-cholestane-3 beta,6 alpha-diol are present in marine invertebrates and were synthesized for the purposes of biologic testing.