a. Compound $\mathbf{J}$ is the major product formed in the reaction of compounds $\mathbf{H}$ and $\mathbf{I}$ as shown below:
(i) Draw the chemical structure of product $\mathbf{J}$.
[3 marks]
(ii) Draw and discuss in detail the reaction mechanism for the formation of compound $\mathbf{J}$ from starting materials $\mathbf{H}$ and $\mathbf{I}$. What is the name of this type of reaction?
[15 marks]

Question

Accepted Answer

∻Solution∻ ‖ 1 ⋮ **Predict the product J**: Given the reaction conditions and the molecular formula of the product $C_{11}H_{12}O_3$, we can deduce that a Claisen condensation followed by an acid-catalyzed cyclization occurs. ‖ ‖ 2 ⋮ **Draw the structure of J**: Based on the Claisen condensation, the ethyl group from compound I will form a bond with the carbonyl carbon of compound H. After cyclization, the final product will have a six-membered ring attached to the benzene ring, forming a 3,4-dihydro-2H-chromen-2-one structure. ‖ ‖ 3 ⋮ **Reaction mechanism**: The mechanism involves the deprotonation of compound I by NaOEt to form an enolate, which then attacks the carbonyl carbon of compound H. After the condensation step, acid-catalyzed cyclization leads to the formation of the chromenone ring system. ‖ ‖ 4 ⋮ **Name of the reaction**: This reaction is a combination of a Claisen condensation and an acid-catalyzed cyclization, which can be referred to as a Claisen-Schmidt condensation followed by a cyclization to form the chromenone system. ‖ ∻1 Answer∻ ⚹ The chemical structure of product $J$ is a 3,4-dihydro-2H-chromen-2-one derivative with the molecular formula $C_{11}H_{12}O_3$. ⚹ ∻2 Answer∻ ⚹ The reaction mechanism involves a Claisen condensation followed by an acid-catalyzed cyclization to form the chromenone ring system. The reaction is a combination of Claisen and Schmidt condensation followed by cyclization. ⚹ ∻Key Concept∻ ⚹ Claisen condensation and cyclization ⚹ ∻Explanation∻ ⚹ The reaction between compounds H and I under basic conditions leads to the formation of an enolate, which attacks the carbonyl carbon of another molecule to form a β-keto ester. Subsequent acid-catalyzed cyclization yields the chromenone ring system. ⚹◊What is the molecular formula of compound J formed in the reaction of compounds H and I⍭ Generate me a similar question◊

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