The Crystal Structures of the α- and β-Diastereomers of 4,5-Epoxy-cholestan-3-one

Synthesis of Symmetrical and Hybrid Dimeric Steroids by Double Suzuki–Miyaura Cross Coupling of 4-Bromo-3-oxo Steroids and Benzene-1,4-diboronic Acid

“…The structure of 4-bromo-cholest-4-en-3-one (4) consists of three six-membered rings, one five-membered ring and a 6-methylheptan-2-yl side chain attached to C-17. All rings are trans fused, analogously to what has been previously reported 8. The six-membered rings(A, B and C) adopt distorted half-chair, chair and chair conformations respectively.…”

“…Crystal array of the epoxide 7b viewed along the b-axis and with perspective to plane formed by a-c axes emphasizing the R1 1(8) motif.As in compound 4, in the structure of (25R)-4-bromo-spirost-4-en-3-one (8) (Figure SF-5) the A/B, B/C and C/D rings are trans-fused, whereas the cyclopentane ring D is cis-fused to the tetrahydrofuran E ring, as reported of other steroid sapogenins. 11 The E rings [O-2)/C-16/C-17/C-20/C-22] is attached to F ring [O-3/C-22-C-26)] through a spirocenter at C-22.…”

Biotransformation of Neoruscogenin by the Endophytic Fungus Alternaria eureka

“…The carbon observed at δ C 63.4 was ascribed to C-5 on the basis of its key HMBCs to H 3 -19 (δ H 1.55) and H 2 -4 (δ H 2.77, 2H, m). When the high-field shift of C-5 was evaluated together with the remaining index of hydrogen deficiency, the presence of an epoxide moiety was evident between C-5 and C-6. , Based on the NOESY cross-peaks between H-7 and H-8β/H-15β, C-14­(O H ) (δ H 5.61), and H-9α (δ H 2.88) and the absence of correlation between HO-7 and HO-6, C-7 and C-14 (OH) were α-cofacially oriented, whereas the epoxide ring had β-orientation. Thus, the structure of metabolite 15 was elucidated as 5β(6)-epoxyspirost-25(27)-ene-1β,3β,7α,14α-tetraol.…”