Under catalysis of NaOH or KOH adsorbed on glass wool and by using steam distillation, (20R,S)-4,4,5,14-tetramethyl-18,19-dinor-13,17-seco-5β,8α,9β,10α,14β-cholestane-13,17-dione (1) and 3,14-dioxo-14,15-seco-5α-cholestan-15-al (4) gave good yield (>59%) of the corresponding tricyclic compounds (8a, 8b and 10a) via a retro-Michael reaction at 250 °C. While 5-oxo-4-nor-3,5-secocholestan-3-oic acid (6) and ethyl 5-oxo-4-nor-3,5-secocholestan-3-oate (7) afforded low yield (<15%) of the retro-Michael cleavage products (12a, 12b) at the same conditions. Thus, the retro-Michael reaction worked well for 1,5-diketones and 1,5-keto aldehydes but gave poor yield for 1,5-keto esters and 1,5-keto acids.
在玻璃棉上吸附NaOH或KOH的催化作用下,通过蒸汽蒸馏,在250°C条件下,(20R, S)-4,4,5,14-四甲基-18,19-二脱-13,17-去氧-5β,8α,9β,10α,14β-胆甾烷-13,17-二酮(1)和3,14-二氧-14,15-去氧-5α-胆甾烷-15-醛(4)通过逆Michael反应产生了相应三环化合物(8a、8b和10a),收率较高(>59%)。而5-氧-4-去氧-3,5-去氧胆甾烷-3-酸(6)和乙酸乙酯5-氧-4-去氧-3,5-去氧胆甾烷-3-酸酯(7)在相同条件下产率较低(<15%),逆Michael裂解产物(12a、12b)。因此,逆Michael反应对于1,5-二酮和1,5-酮醛效果良好,但对于1,5-酮酯和1,5-酮酸产率较低。