18-Substituted steroids, part 14. The high-field 1H and 13C nuclear magnetic resonance spectra of aldosterone; full assignments for the main equilibrating forms in solution
- 1 January 1987
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 9,p. 1247-1252
- https://doi.org/10.1039/p29870001247
Abstract
Aldosterone exists in solution predominantly as an equilibrating mixture of the 20-oxo-11,18-hemiacetal (2) and the 11,18-epoxy-18,20-hemiacetal (1), resulting in distinct but superimposed n.m.r. spectra. Full assignments of the 1H and 13C spectra have been achieved by carrying out a 13C–13C connectivity experiment (INADEQUATE) to identify the set of 13C signals for each of the two forms, followed by the use of 1H–13C heteronuclear shift-correlated spectroscopy, aided by a phase-sensitive double quantum filtered COSY and 2D J-resolved spectra (1H), with a few selective nuclear Overhauser difference measurements. This permitted assignments of all the 1H and 13C chemical shifts and almost all of the two- and three-bond interproton coupling constants for each tautomer.Keywords
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