Question

2. (5 pts) Provide a mechanism for this rearrangement. Include all intermediates. Show all electron pushing. Give a reason why this process occurs; that is, what makes this reaction an exothermic process?

Answer 1

in this mechanism there is formation of six membered ring from 5 embered ring , this is becous steric reason 5-membered ring is less stable than the the six membere ring. hence molecule get to stable by releasing energy hence the process is exothrmic process.

in this 1 on reacting with 1% H2S04 the ketonic carbonyl get protonated which can accept the electron density from the ring and carbocation is generated on same tome nearest 0-C bond break and which can attack on the carbocation hence ring get expanded to 6 membered 2. Finaly the ring get aromatise 3 by accepting proton by HS04- ion .To obtained the product 4.

OH 16H S0 Mechanism OH OH он он HS0 4