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I really like your "draw it ugly," strategy. I was struggling a lot with the ring expansion even through I understood it theoretically but, drawing it ugly first makes the ring expansion so much less visually overwhelming , and then once I see what belongs where I redraw it as the "pretty" version.
Rearrangements that involve cyclic intermediates (with either ring expansions or contractions) are always tricky, so why make your life more difficult by doing multiple manipulation all at the same time? So, yeah, just redraw your molecule, erase one bond, make a line for another bond and theeeeen redraw it nicely!
I'm wondering why the ring expansion choice was not a cyclohexane from a cyclopentane on the right side, but instead making a cyclopentane from a cyclobutane on the left side?
The overall stability gain going 4->5 is much greater than going 5->6. Also (and we don’t cover it in the sophomore level course) the sigma bonds (HOMO) in a 4-membered ring have a higher p-character bringing them closer to the energy level of the LUMO empty p-orbital of the carbocation making a more favorable HOMO-LUMO interaction than a similar overlap with the 5-membered ring.
Please, like, share, and comment to help promote this video!
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OMG thank you for "drawing it ugly" first I would have been so lost otherwise
I really like your "draw it ugly," strategy. I was struggling a lot with the ring expansion even through I understood it theoretically but, drawing it ugly first makes the ring expansion so much less visually overwhelming , and then once I see what belongs where I redraw it as the "pretty" version.
Rearrangements that involve cyclic intermediates (with either ring expansions or contractions) are always tricky, so why make your life more difficult by doing multiple manipulation all at the same time? So, yeah, just redraw your molecule, erase one bond, make a line for another bond and theeeeen redraw it nicely!
Can you make a video on girgnard reagent please
I'm wondering why the ring expansion choice was not a cyclohexane from a cyclopentane on the right side, but instead making a cyclopentane from a cyclobutane on the left side?
The overall stability gain going 4->5 is much greater than going 5->6. Also (and we don’t cover it in the sophomore level course) the sigma bonds (HOMO) in a 4-membered ring have a higher p-character bringing them closer to the energy level of the LUMO empty p-orbital of the carbocation making a more favorable HOMO-LUMO interaction than a similar overlap with the 5-membered ring.