The Key Is The The Carbocation
I had a student ask if I could make up an E1 question that incorporates many different products. Well, here it is…
Since we know this is an E1 mechanism, we first need to generate a carbocation:
Look for alpha hydrogens
Next, we need to look for hydrogens that are alpha to the carbocation (hydrogens on the adjacent carbon(s):
There is only one site with hydrogens; the other is a quaternary center.
As you have guessed, this can’t be the only final product and the whole story…there must be something else we can do. Let’s take a look at the quaternary center again:
We can see the driving force for this migration. We can go from a secondary carbocation to a teriary carbocation, which is more stable. Now, let’s see how many products we can form:
With this alkyl migration, we were able to squeak out 3 more products (a total of 4 products). See if you can rank them from highest to lowest priority.