A novel stereospecific rearrangement of 3-substituted B-homo-5-azasteroids to their A-nor analogs. Preparation, stereochemistry, and conformational studies

Unambiguous assignment of 13C NMR signals in epimeric 4,5-epoxy-3-oxo-steroids assisted by X-ray diffraction and gauge invariant atomic orbitals calculation of absolute isotropic shieldings

“…In particular, steroids containing the 4,5-epoxy-3-oxo moiety are of special utility as synthetic precursors of a wide variety of polyfunctional derivatives or rearranged compounds. [1][2][3][4][5] 4,5-Epoxy-3-oxo-steroids can be prepared in moderate to good yield and varying diastereoselectivity by treatment with different reagents that include peracids, 4 H 2 O 2 in alkaline media, 5 dioxiranes 6 and more recently magnesium bis(monoperoxyphthalate) hexahydrate. 7 In spite that such compounds have been extensively employed as synthetic precursors for different polyfunctional or rearranged steroids, no complete and unambiguous assignment of the 13 C NMR signals of such compounds is available.…”