Acid/Base Opening of Expoy Rings

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emitpeels

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Hey guys quick question. I understand that in acidic conditions you attack the more substituted side of the epoxy ring, and basic attacks the less substituted side. My confusion comes in when certain parts of the molecule invert. Can anyone help me? I am confused! Thank you.

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Hey guys quick question. I understand that in acidic conditions you attack the more substituted side of the epoxy ring, and basic attacks the less substituted side. My confusion comes in when certain parts of the molecule invert. Can anyone help me? I am confused! Thank you.
HOWEVER......Here is a shorter and more concise answer......... As a good general rule of thumb, if you run the reaction in acid, attack the more substituted carbon. If you run the reaction in base, attack the less substituted carbon. If the epoxide has only one R group, often mixed results can occur, which is a very fine point that the Klein bool nor the McMurry book fail to address. If you are attacking a CHIRAL center, regardless of acid or base an INVERSION would occur.

Hope this helps.

Dr. Romano
 
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