3
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Twisting in Chair and Twist Boat

In this image, does the arrows indicate correct rate of reactions? The upper arrow is longer and lower is shorter.

According to me Chair is more stable than Twist Boat. Does axial and equatorial arrangement of the two -C(CH3) groups play a role?

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  • $\begingroup$ Check out this paper: pubs.acs.org/doi/abs/10.1021/jo051654z. Two reasons are mentioned: 1. Steric repulsion between an axial methyl group and the axial hydrogens on carbons 3 and 5 of the ring; 2. Hyperconjugation interactions involving the methine hydrogen. I don't have time to post an answer now, so if anyone can do it using this reference as a starting point -- please feel free to do so. $\endgroup$ – andselisk Sep 25 '17 at 16:11
  • $\begingroup$ Basically, a tert-butyl substituent is so bulky that it will never occupy an axial position. $\endgroup$ – Jan Sep 26 '17 at 8:07
  • $\begingroup$ Also note that the thin end of a hashed wedge bond should always go away from the ‘stereocentre’ i.e. from the quarternary carbon and not the methyl group here. $\endgroup$ – Jan Sep 26 '17 at 8:17

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