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Steroids: reactions and partial synthesis (1999)

“…The partial synthesis of 18-norestradiol 26 from estrone has been described. 85 The effect has been examined 86 of metal ions on the formation of adducts between 16α-hydroxyestrone 27, a major human metabolite of estrone, and various amines. The acid-catalysed cyclization of steroidal arylamines, e.g.…”

A Practical and Facile Route for the Preparation of 18-Norandrostan-17-ones from Androstan-17-ones Using SmI2-Promoted Cyclization and Dehydroxylation

“…Because of their utility in biological research, significant effort has been made to develop synthetic routes to 18-norsteroids . Although previous routes to 18-nor-17-ketosteroids have been published, there remains a need for a more efficient and practical route for the laboratory-scale synthesis of these steroids from commercially available 17-ketosteroid precursors. Herein, we report a novel synthetic route that satisfies this need.…”

“…A significant drawback to the “abnormal” Beckmann rearrangement route to 18-nor-17-ketosteroids, which proceeds via alkene-nitrile rearrangement products (e.g., 3 and 4 , Scheme 1), has been the lengthy reaction sequence required for the reconstruction of the 18-norandrostan-17-one D-ring 2h. Realizing that products 3 and 4 are readily converted into ketone-nitriles 5 and 6 , this drawback can be obviated by application of newly developed intramolecular ketone-nitrile reductive coupling reactions. − SmI 2 effects intramolecular ketone-nitrile reductive coupling reactions to give α-hydroxyketones and can also reduce these products to their corresponding ketones. , Hence, these two SmI 2 -promoted reactions make possible an expeditious route from abnormal Beckmann rearrangement products to 18-nor-17-ketosteroids.…”

Preparation of 17β-(Hydroxymethyl)-3-methoxyestra-1,3,5(10)- trien-18-oic Acid 18,20-Lactone, a NewC(18)-Oxygenated Steroid

“…± Albeit 18-norsteroids appear quite similar to their naturally occurring counterparts ± they differ only in the missing Me group ± their synthesis has proven a rather difficult endeavour, and is in the case of 18-norestradiol (1) also somewhat ambiguous [1 ± 3]. In our attempt for a new approach to the latter compound [4], we reinvestigated the various techniques to functionalize the angular Me (18) group in estradiol (2) itself and in its derivatives. Apart from the known retro-pinacol rearrangement 1 ) and Beckmann fragmentation [6] of the corresponding 17-ketoxime, we examined an intramolecular radical-mediated oxygenation, the well-known hypoiodite reaction [7a].…”

“…Furthermore, the saponification of the corresponding saturated nitrile leads to a 3 : 1 mixture, with preference for the 17bdiastereoisomer 4. ) In the course of the structure elucidation of ouabagenine, a cardenolide from Acokanthera schimperi, etianic acid derivative 9 was prepared by hydrogenation of the corresponding D 14 compound, a degradation product[15] 5. )…”