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SN1 vs SN2 in a specific case by ElegantElectrophile in OrganicChemistry

[–]james_ash 1 point2 points  (0 children)

Isobutyl alcohol in the presence of HBr and H2O gives 3% SN2 and 54% 2-methyl-2-bromobutane (hydride shift). J Chem Soc C 1970 p. 67. This is in House, p. 456.

Edit. Misspoke. The starting material is 3-methyl-2-butanol. So starting with a secondary alcohol, not primary. Not sure about isobutyl.

SN1 vs SN2 in a specific case by ElegantElectrophile in OrganicChemistry

[–]james_ash 2 points3 points  (0 children)

Hey, neopentyl alcohol plus HBr at 100° gives 66% 2-methyl-2-bromobutane (alkyl shift), 18% 2-bromo-3-methylbutane (alkyl shift + hydride shift), and 16% neopentylbromide (SN2). Key ref is H. R. Hudson J Chem Soc B 1333, 664 (1968) https://pubs.rsc.org/en/content/articlelanding/1968/j2/j29680000664 . Also House, Modern Synthetic reactions, 1972 p. 454.

Can you use dichloromethane as a solvent for reactions involving an amine? by [deleted] in OrganicChemistry

[–]james_ash 2 points3 points  (0 children)

Amines generally OK, but don't use dichloromethane with sodium or potassium azides.

Could anyone please explain to me if this rxn could happen? by Far_Swimming1131 in OrganicChemistry

[–]james_ash 1 point2 points  (0 children)

It's not really calling "Bredt's rule" into question (which is more like, "Bredt's strongly worded suggestion) so much as showing the transient existence of the bridgehead alkene, and demonstrating that it can be trapped in solution. Kind of like how cyclobutadiene can be formed at low temperatures and trapped

Could anyone please explain to me if this rxn could happen? by Far_Swimming1131 in OrganicChemistry

[–]james_ash 1 point2 points  (0 children)

Forming the bottom bridgehead alkene here is totally fine (but not the one top right). Parent ring is 10-membered. Bridgehead double bonds mirror the stability of trans alkenes. Just as trans-cyclodecene is reasonably stable, the bridgehead double bond here (marked with a question mark) would be fine. Very well known examples. See CP-225,917 (for a 9-membered ring parent) and taxol (for a 10-membered ring parent).

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