What are the diastereomers and enantiomeric pairs of the compound below where A are chiral groups (central chirality)? There should be 3 diastereomers and 3 enantiomeric pairs (last page).

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I previously asked a question about tetra-substituted allenes.

  • $\begingroup$ Have you tried to apply the Newman projection method I described in your previous question? If so, what problem do you run into? Can you draw the the diastereomers you came up with? Which ones are chiral? $\endgroup$ – ron Sep 6 '15 at 16:22
  • $\begingroup$ Can't find three of them. I got the R,R (S,S), R,S (S,R), those are just two. $\endgroup$ – EJC Sep 6 '15 at 17:04
  • $\begingroup$ There are 2 R,R diastereomers, both chiral and 1 chiral R,S diastereomer - does that help? $\endgroup$ – ron Sep 6 '15 at 17:09
  • $\begingroup$ Are the two R,R isomers are connected through axial chirality? $\endgroup$ – EJC Sep 6 '15 at 17:11
  • $\begingroup$ yes, sighting down the allene (Newman) one R,R diastereomer has front R at 0° and back R at 270°; other R,R diastereomer has front R at 0° and back R at 90° $\endgroup$ – ron Sep 6 '15 at 17:14

These are the three diastereomers with their enantiomers on the right side. The top and middle diastereomers are connected via axial chirality (R and S are used to mark the configuration of A groups).

enter image description here

  • 1
    $\begingroup$ Nice work, but all 3 are axially chiral. $\endgroup$ – ron Sep 6 '15 at 17:38

I'm not that good at this but here is something to work on. Each row is a pair of mirror images. Grey structures in 3rd row are identical to the respective 2nd row ones. enter image description here


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