Sugar ring pucker: Difference between revisions

For a 5-membered ring with perfectly tetrahedral geometry of each atom in the ring, there is minimal strain if the ring were planar (~355 degree rotation around the ring instead of 360). However, all hydrogens/substituents would be ecplised, which is not the lowest energy conformation.[https://www.sciencedirect.com/science/article/pii/B9780128128381500049] To relieve the strain, one or two atoms move out of the plane. The conformation with one atom out of the plane is called <scene name='90/900784/Cyclopentane/3'>envelope</scene> (endo or exo depending on whether the atom is above or below the plane). You can show the 5 possible planes defined by three consecutive ring atoms by clicking on the radio buttons below. In three cases, the remaining two atoms are on the same side of the plane. In two cases ("123" and "512"), carbon 4 is moved out of the plane, making this conformation a carbon-4 envelope.

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