Question

4. (15 Points) Pericyclic Reactions: The transformation below can be described as a pericyclic reaction followed by a polar-acidic mechanism, where the acid is not shown because it is picked up from the environment. (a) Start by redrawing the starting material below, and show how the pericyclic reaction occurs with curved arrows. (b) Specify the type of pericyclic reaction it represents and the name reaction. (c) If you've done the pericyclic reaction correctly, your product will be an enol. From your pericyclic reaction product, show a detailed mechanism for how the enol tautomerizes to its keto form under acidic conditions (use H and 'base: when needed). (d) On the final product that I drew, number the carbons to reflect what occurred in this reaction, and next to the product, specify bonds broken and bonds formed. 2 4 heat 5 7

Answer 1

It is an example for Cope rearrangement by [3,3]-sigmatropic rearrangement.

After rearrangement, tautomerization of enol to ketone occured.

-4 new bond