Oxacycloalkenones are prepared by reacting a cycloalkenone with a base in the presence of a dioxygen source in a suitable solvent and isolating the desired product. 1-Hydroxy 2-oxa-3-oxo-.DELTA..sup.4 steroids are convenient synthetic precursors to 2-oxa-3-oxo-.DELTA..sup.4 steroids which find use in modern clinical therapy.
Treatment of 3-oxo-4, 5-oxido steroids with lead tetraacetate results in acetoxylation in the 2α-position as could be shown by independent synthesis of the acetoxylated compounds. The products of this reaction rearrange even under very mild conditions (chromatography on silicagel or alumina) to the corresponding 2,3-dioxo-Δ4 compounds. The influence of structure and conformation of the various intermediates
A facile two-step high yield approach to 2-oxasteroids
作者:Aryeh A. Frimer、Judith Hameiri-Buch、Shlomo Ripshtos、Pessia Gilinsky-Sharon
DOI:10.1016/s0040-4020(01)88175-8
日期:1986.1
generating rapidly (< 4 hrs) and in highyield the corresponding enol (2-hydroxy-3-oxo-Δ1,4 analog) When the reaction is then allowed to continue at room temperature for several days, the enol is further autoxidized to the related lactol (1-hydroxy-2-oxa-3-oxo-Δ4 analog) in overall yields generally in the range of 85–95%. Sodium borohydride reduction of the lactol yields the pharmacologically important