Sur l'acces aux 16α-methyl 17α-hydroxy steroides

Steroidal estrogens

“…The formation of 3-(l-pyrrolidino)estra-l,3,5(10)triene-9a, 17/3-diol (CXLV) in the base-catalyzed aromatization of 17/3-hydroxy-9o;, 10a-oxidoestr-4-en-3-one (CXLIII) (137) has been discussed in section VI.A.3.a. This reaction has also been reported in the patent literature (300).…”

Bc → BCD → Abcd

“…However, in alkaline medium, the major product obtained had the 9al0a-structure, which was readily epimerized through the enolization of the 5-oxo group, into the 9o:,10/?-isomer 20. Cyclization and hydrolysis of the latter afforded 19-nortestosterone (21) [8,9,[17][18][19][20][21][22]. has also been obtained by various modifications [12,[23][24][25] of the procedure described above.…”

“…The diketone 19 (R = PhCO) also served as the starting material for the synthesis of 10-allyl steroids [42][43][44][45][46][47][48] (Scheme 10-4). Direct allylation of the ketal 36, obtained from 19 (R = PhCO), was followed by hydrolysis and cyclizaton to yield the 10/3-allyl derivative 37.…”

“…In another modification [42,[44][45][46][47][48], the diketone 19 (R = PhCO) was first converted to the epoxide 38, by the action of perphthalic acid. The 9a?,10a-configuration of this epoxide was established by X-ray diffraction as well as by circular dichroism studies.…”