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Conformations of the securinine alkaloids as studied by high field 13C, 1H and 2-D NMR, and molecular mechanics calculation

✍ Scribed by Peter D. Livant; John A. Beutler

Publisher: Elsevier Science
Year: 1987
Tongue: French
Weight: 568 KB
Volume: 43
Category: Article
ISSN: 0040-4020
DOI: 10.1016/s0040-4020(01)86830-7

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✦ Synopsis

On the basis of C-H correlation experiments, COSY, and other 2-dimensional nmr evidence, the 'H and 13C-nmr assignments for securinine are revised from those previously proposed. Assignments are also made for the biologically relevant hydrochloride salt of securinine in D20. The spectra of allosecurinine are completely assigned and assignments for securinol A are presented for the first time. Implications of the nmr results for the conformational preferences of these alkaloids are discussed in light of molecular mechanics calculations. Securinine (1) has been shown to be a stereospeciflc GABAA receptor antagonist.' Since it would appear to be a fairly intlexible molecule with a welldeflned geometry, securinine offers the hope that it might aid in understanding the shape of the GABA receptor site. It was of interest, therefore, to examine the conformational preferences of securinine in solution. This was done by us recently using low-Reid NMR and relying on lanthanide shitt reagent information2 We have now re-examined securinine itself as well as several alkaloids of the securinine family (2. 3) using high-field NMR and various P-dimensional techniques. The conformational implications of these more reliable data are discussed herein.

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