NMR‐based conformational analysis of perezone and analogues |
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| Authors: | L Gerardo Zepeda Eleuterio Burgueño‐Tapia Nury Pérez‐Hernández Gabriel Cuevas Pedro Joseph‐Nathan |
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| Institution: | 1. Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, , México, D.F., 11340 Mexico;2. Escuela Nacional de Medicina y Homeopatía, Instituto Politécnico Nacional, , Mexico, D.F., 07320 Mexico;3. Instituto de Química, Universidad Nacional Autónoma de México, , Ciudad Universitaria, D.F., 04510 Mexico;4. Departamento de Química, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, , México, D.F., 07000 Mexico |
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| Abstract: | Complete assignment of the 1H NMR chemical shift and coupling constant values of perezone (1), O‐methylperezone (2) and 6‐hydroxyperezone (3) was carried out by total‐line‐shape‐fitting calculations using the PERCH iterative spectra analysis software (PERCH Solutions Ltd., Kuopio, Finland). The resulting simulated spectra for the three compounds showed strong similarity to their corresponding experimental spectra. Particularly, all vicinal, allylic and homoallylic coupling constant values for the side chain of the three compounds were very similar, thus revealing that the conformation of these three molecules in solution is indeed almost identical. This fact is in agreement with extended side chain conformations over folded chain conformations because 1, 2 and 3 undergo completely different intramolecular cycloaddition reactions. In addition, results of double pulsed field gradient spin echo NOESY 1D experiments performed on perezone (1) were unable to provide evidence for folded conformers. Copyright © 2013 John Wiley & Sons, Ltd. |
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| Keywords: | perezone hydroxyperezone O‐methylperezone pipitzol 1H NMR iterative NMR spectral analysis NOE |
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