# Mechanism for reaction of enol ether with HBr

Please refer to the image for the question. I tried two different mechanisms for the reaction (1 and 2) and ended up with two different products. Now I can't decide which of the two mechanisms would give the major product.

I think that mechanism 1 should give the major product as it involves the formation of a double bond between $\ce{C}$ and $\ce{O}$ atom which is thermodynamically favorable. Is this reasoning correct?

The answer to the question had given product of mechanism 2 as major product. But I don't know if it is really correct or not.

• The last s step in Mech. 2 is reversible allowing liberate bromide to participate in Mech. 1. In Mech. 1 the cation in the upper right may undergo SN2 vs. SN1 reaction with bromide. In all, you did well! – user55119 Apr 25 '18 at 17:53
• @user55119 Thanks! That's another point to consider. One of my friend said that mechanism 1 involves cleavage of a C-O bond and so the reaction should not occur through Mech. 1. Is what he is saying correct? – FreakyLearner Apr 26 '18 at 8:09
• Both mechanisms involve cleavage of a C-O bond at some point. – user55119 Apr 26 '18 at 16:16