Synthesis of steroidal azides. Part 1. Stereospecific vicinal azidohydroxylation of steroidal olefins

Highly Diastereoselective Construction of Carbon– Heteroatom Quaternary Stereogenic Centers in the Synthesis of Analogs of Bioactive Compounds: From Monofluorinated Epoxyalkylphosphonates to α-Fluoro-, β-, or γ-Amino Alcohol Derivatives of Alkylphosphonates

“…A conventional way to get the vicinal azido alcohols involves epoxides ring-opening (Benedetti et al, 1998 ; Fringuelli et al, 1999 ; Amantini et al, 2002 ; Badalassi et al, 2004 ; Nesterov and Kolodiazhnyi, 2007 ; Głowacka, 2009 ) or displacement of halohydrins (Draper, 1983 ; Iacazio and Réglier, 2005 ) under acidic/basic conditions with the application of different azide sources as well as chemoselectivity by the reduction of α-azido ketones (Rao et al, 1992 ; Ordóñez et al, 2003 ; Ankati et al, 2008 ). As an example, the opening of diethyl ( S )-2,3-oxiranepropylphosphonate with sodium azide in the presence of (NH 4 ) 2 SO 4 resulted in the formation of single regioisomer ( R )-3-azido-2-hydroxypropylphosphonate as well (Głowacka, 2009 ).…”

Synthesis of steroidal azides. Part 3. Addition of halogen azides to Δ6-steroids

“…These results contrast with the sodium azide treatment of the analogous 7a-azido-6p-chloro-4-en-3-one (1 3) and the 6p,7a-diazido-4-en-3-one (14) which undergo a simple elimination of hydrazoic acid to yield exclusively the 6-chloroand 6-azido-4,6-dien-3-ones ( 6) and ( 7) respectively.' Since the functionality at C-7 is identical in each case, the particular pathway taken by the reaction must be determined by the ease at which the 6-substituent acts as a leaving group, relative to that at C-7.…”

Steroids: reactions and partial syntheses

“…Primary nitro-compounds gave much lower yields than secondary ones.77 Oestrone oxime is reduced by diborane or sodium borohydride to the 17p-hydroxylamine, which reacts with ketones or aldehydes to give the nitrones (94) in a reversible reaction.78 Sodium azide and chromium trioxide in acetic acid, acting as a source of chromyl azide, convert a 5,6-olefin into the 6pazido-5a-hydroxy-compound and a 6,7-olefin largely into the 7a-azido-6~-hydroxy-compound. 79 Lead tetra-acetate and trimethylsilyl azide react with 17a-acetoxy-6,7-didehydroproges--terone to give the 6P,7a-diazido-compound as the major andthe q R~ 7a-azido-6-ketone as the minor product; the 1,4,6-triene behaves similarly. Treatment of the diazide with sodium azide or with tetramethylammonium fluoride yielded the 6-azido-4,6diene-3-one.…”