Steroid Ring D Torsional Angles and Conformations from X-Ray Data

The crystal and molecular structure of an addition compound of cholic acid and ethanol

“…The D ring of cholic acid is best characterized as a fl-envelope although this is not exact (Brutcher & Leopold, 1966;Brutcher & Bauer, 1962). It is actually between a half chair and a fl-envelope but closer to the % fl-envelope.…”

The structure of Δ-8,l4-anhydrodigitoxigenin, C23H32O3, by direct phase determination

“…Comparisons of the conformations of steroids are facilitated by the computation of torsion angles about ring bonds (Brutcher & Leopold, 1966). The torsion angles for ADTG are presented in Table 7, usingthe sign convention of Brutcher & Leopold.…”

“…Torsion angles have been calculated for several steroidal ring D envelopes (Brutcher & Leopold, 1966) from X-ray data. In all examples previously reported, atom C(13) or C(14) (as in DTG with.…”

The structure of 6α,7α-difluoromethylene-l6α-methyl-11β,17α,2l-trihydroxypregn-4-en-20-one-[3,2-c]-2'-phenylpyrazole 21-(p-bromobenzoate)

“…The torsion angle C(14)-C(15)-C(16)-C(17) is 5.5 °, indicating that the D ring is a slightly distorted fl-envelope (Brutcher & Leopold, 1966); C(13) is displaced 0.707 A from the least-squares plane through C(14), C(15), C(16) and C(17). The fold angle about C(14)-C(17) is near 45 °.…”