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

Alcohols as Efficient Intermolecular Initiators for a Highly Stereoselective Polyene Cyclisation Cascade

“…Repetition of the RCM reaction on compound 6 g (see Supporting Information) allowed for the formation of 19 (this compound has been previously prepared by a lengthy degradation of estradiol itself). Because compound 19 has been transformed into 18‐nor‐estradiol in two steps, [18] our synthetic work constitutes a formal synthesis of this unnatural steroidal analogue whose congeners have been reported to possess interesting biological activity [19a–e] . In this regard, it is interesting to note the stereoselective hydroboration reaction [18] of 17 , using conditions reported in the literature.…”

“…Because compound 19 has been transformed into 18‐nor‐estradiol in two steps, [18] our synthetic work constitutes a formal synthesis of this unnatural steroidal analogue whose congeners have been reported to possess interesting biological activity. [ 19a , 19b , 19c , 19d , 19e ] In this regard, it is interesting to note the stereoselective hydroboration reaction [18] of 17 , using conditions reported in the literature. In our hands, 17 gave the two syn addition products exclusively, in a 61 : 39 ratio, with the major product 18 possessing the desired trans 6,5‐ring junction.…”

Steroids: reactions and partial synthesis

“…A practical route has been described 63 64 There have been investigations on the palladium catalysed carbonylation of 17-iodoandrost-16-enes 23 in the presence of NaBPh 4 and carbon monoxide to yield phenylketones 24 and in the presence of substituted hydroxylamines, to give hydroxamic acid derivatives. [65][66][67] The synthesis of 3βhydroxy[4-14 C]-16α-bromo-5α-androstan-17-one from [ 14 C]testosterone has been described.…”

Stereoselective Domino Carbocyclizations of γ- and δ-Cyano-N-tosylhydrazones with Alkenylboronic Acids with Formation of Two Different C(sp3)–C(sp2) Bonds on a Quaternary Stereocenter

“…Finally, to investigate the applicability of this transformation in a more demanding environment, we studied the modification of the structure of an enantiopure natural product: the steroid androsterone (Scheme ). To this purpose, the cyanoketone 18 was synthesized from androsterone through a straightforward previously described methodology . Formation of the tosylhydrazone 19 proceeded uneventfully from 18 .…”