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I synthesised a dihydropyridine molecule today and recieved my NMR. I am wondering where the complex splitting for the 7 and 22 protons is coming from. My spectrum:

  • 1.26ppm, triplet, 6H
  • 2.33ppm, singlet, 6H
  • 4.16ppm, multiplet, 4H
  • 5.20ppm, singlet, 1H
  • 5.65ppm, singlet, 1H
  • 5.94ppm, doublet of doublets, 1H
  • 6.21ppm, doublet of triplets, 1H
  • 7.21ppm, singlet, 1H

Here is the multiplet form 4.16ppm:

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The molecule:

enter image description here

Thanks very much!

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    $\begingroup$ The protons at 7 and 22 are diastereotopic because of the stereogenic center at 9. The hydrogens at the -CH2- are non-equivalent, have different chemical shifts and couple with each other in each -CH2-. Look here: chemistry.stackexchange.com/questions/95027/… $\endgroup$ – user55119 Oct 27 '20 at 21:15
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    $\begingroup$ On closer inspection C9 is non-stereogenic but that doesn't change the argument. Each methylene has -CH(a)H(b). $\endgroup$ – user55119 Oct 27 '20 at 22:32

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