# Grignard reaction with cycloheptatriene

I'm having trouble with the following set of reactions and their products.

Product A is achieved by exploiting the unique aromaticity of cycloheptatriene cations. When A is treated with the Grignard reagent $$\ce{MeMgI}$$, a mixture of B and C is obtained. Treating A with catalytic amount of $$\ce{HCl}$$ in $$\ce{CCl_4}$$ furnishes isomer A’, which is again converted into a mixture of B and C upon treatment with Lewis-acidic Grignard reagents.

For A I got the following structure, since I could not figure out how the aromaticity of the first structure is affecting the reaction.

This cannot be correct, since the grignard reaction would produce only one product and not a mixture of two.

Having done some reasearch online on the resonance structures of cycloheptatriene, I thought of the following structure for A. But this would not produce two different products either if I am not mistaken.

• I think your initial structure for A is correct. Consider that MeMgI can attack A in a 1,2 mode or 1,4 – Waylander May 14 at 11:27
• Would that result in the products B and C being 1) the one below my structure for A and the other 2) being the same as 1) but with methyl group moved to the adjacent carbon in the cycloheptatriene structure? – Pöytä Laatikko May 14 at 12:10
• 1) correct 2) Me group in the benzylic position on benzocycloheptadiene ring - like your last structure but without the OH – Waylander May 14 at 13:23

The product A, shown below, is formed by first reducing the ketone to a secondary alcohol with $$\ce{LiAlH_4}$$ and then by adding a methyl group to form an ether using the reagent $$\ce{CH_3I}$$.
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Next the grignard reaction with product A will form two products. The grignard reagent $$\ce{MeMgI}$$ can attack A in a $$1$$,$$2$$ or in a $$1$$,$$4$$ mode, due to the unique aromaticity of cycloheptatriene, giving a mixture of products B and C, the structures of which are shown below.
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