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The picture (a) is from a organic chemistry book by Clayden, Chapter 32. That means drawing (a) is right expression of the molecule.

What I wonder is that is it possible for (a) to ring-flip? If so, is (b) correct as a ring flip version of (a)? If it's not possible to ring flip, why?

Second question: Is drawing (c) also valid to draw this molecule? If it's so, is it same with (a)? or is it ring flip of (a)? If it's not, what's wrong with it?

Personally, I thought (c) was the right drawing for the molecule. Below (c), I drew the conformation of cyclohexene. The first conformation has a pseudoaxial hydrogen and the inner side of carbon faces downward. This is why I drew (c) with methyl at pseudoaxial, and inner carbon facing downward. But the book only has a drawing of (a).

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    $\begingroup$ You can also just tell me where I can find those kind of conformation, in book, website, anything because my four organic chemistry books are needless now. $\endgroup$ – Zillai Mar 28 '18 at 15:54
  • $\begingroup$ I noticed that you had typed your question in proper paragraphs to insert a line break use double space or <br>. $\endgroup$ – Avnish Kabaj Mar 29 '18 at 0:09
  • $\begingroup$ I suggest you build a model (simple molymod is fine) - it will all become clear (and much easier than any 2D representation that I could draw for you) $\endgroup$ – NotEvans. Mar 30 '18 at 11:42
  • $\begingroup$ @NotEvans thanks maybe I will buy one later. I don't have one now. Do you know any website that I can see the ringflip molecular form? Chemspider shows me a good 3d image but no function to change conformation. $\endgroup$ – Zillai Mar 30 '18 at 16:09
  • $\begingroup$ You can ring-flip the enone ring but the methyl must be axial to both rings. If the methyl were equatorial, the double bond would be too twisted. In other words in this example, if a double bond is exocyclic to ring B (steroid lettering), there aren't enough carbons in ring A to attached axially to ring B. Models would be helpful. $\endgroup$ – user55119 Apr 5 '18 at 20:11

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