5α-Dihydro­vespertilin acetate

In the title compound, C24H36O4 [systematic name: (20S)-3β-acet­oxy-16α-hydr­oxy-22,23-bis­nor-5α,17β-cholano(22-16)lac­tone], the three six-membered rings adopt classical chair conformations, while the five-membered rings are in envelope conformations. The ester group attached to ring A is in an equatorial position. Rings A/B, B/C and C/D are trans-fused, whereas rings D/E are cis-fused. The structure is devoid of any classical hydrogen bonds. However, non-classical inter- and intra­molecular hydrogen-bonding inter­actions of the type C—H⋯O are present in the structure

(20S)-20-Acetamido-18-chloro-5α-pregnan-3β-yl acetate

In the title compound, C25H40ClNO3, prepared by the thermolysis of (20S)-O,N-diacetyl-20-amino-N-chloro-3β-hydr­oxy-5α-pregnane, the three six-membered rings adopt chair conformations while the five-membered ring is in an envelope conformation. The ester group attached to ring A is in an equatorial position. All the rings are trans-fused. Intra­molecular C—H⋯O and C—H⋯Cl inter­actions occur. The crystal structure is stabilized by inter­molecular N—H⋯O and C—H⋯O inter­actions close contacts occur

N-Haloamides and their applications in natural products synthesis

Bibliography: p. 98-10