A New One-pot Synthesis of 17-Oxo-13α-steroids of the Androstane Series from their 13β-Analogues

Total assignment of 1H and 13C NMR spectra of 13α‐ and 13β‐estrone methyl ethers

“…5,6 Other methods of epimerization have been reported: in one step from 17-keto steroids using 1,2-phenylenediamine and acetic acid 7 or from a 17-oxime 8 or a sulfenimine 9 in turn prepared from a carbonyl group. The 1 H NMR (60 MHz) signal of H 3 -18 of 1 was reported in 1968; 10 a downfield shift of this singlet and a large upfield shift of the H 3 -19 singlet characterize C-13 epimerization of 17-keto steroids of the androstane series.…”

Recent developments in the isolation and synthesis of D-homosteroids and related compounds

“…34,35 These fragmentation products (39) bear two valuable functional groups, a formyl and an allyl group, which allow a wide range of further transformations. An effective, simple epimerization of C-13 has been elaborated for the synthesis of 17-keto-13α-5-androstenes 36 and -estranes. 37 The unnatural 13α derivatives, with C/D cis ring annelation, are of stereochemical and biological interest.…”

17-Oxo-13α-androst-5-en-3β-yl acetate

“…The conformation is strongly influenced by the substituents on ring D. We are interested in the synthesis, chemical transformation and structural investigation of 13steroids. After some unsuccessful early attempts (Butenandt et al, 1941;Nambara et al, 1969;Boar et al, 1977), Yaremenko & Khvat (1994) described an effective method for epimerization at C-13 in the androstane series using 1,2-phenylenediamine in boiling acetic acid. We have also used this method, starting from 17-oxoandrost-5-en-3-yl acetate.…”