O-Chem Question: Chair Conformations

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jdawgydawg

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The answer is A.
I understand that the 13-deoxy-14-epimer is R conformation. But I don't understand why it is "axial". In the TPR solution it says "since C-13 hydrogen is axial, and is in the up configuration, the down configuration on C-14 (which is where the OH group is) will also be axial"
Couldn't it be equatorial as well, depending on how you assign the up, down on the chair representation of the ring? I feel like it's going to be relative to how I draw and label each carbon on the chair conformation...
If C-13 is up equatorial, then C-14 of the epimer has to be down equatorial.

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In fused ring systems, the rings will always want to be in a plane. If the H in question is not axial, that means that the ring would be bent in a concave fashion, which would increase steric clash by a lot. So that's why you see most of the steroids' A, B, C, and D rings are all extended and not bent.
 
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