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Question

The major product formed in the following reaction sequence is

The correct answer is

The reaction sequence described involves the conversion of an alkyne to a ketone through hydroboration-oxidation followed by halogenation and subsequent elimination. Let's break it down step by step:

  1. Hydroboration-Oxidation: The alkyne reacts with catecholborane. Hydroboration adds across the triple bond, followed by oxidation, which typically gives a ketone from an alkyne.
  2. Bromination: The resultant ketone undergoes alpha-bromination using Br2. This creates a bromoketone.
  3. Elimination: Treatment with NaOMe favors the formation of an enone through elimination (E2 mechanism).

Applying these steps to the given structure:

The starting alkyne is a terminal alkyne, which through the described sequence results in the formation of a 2-enone structure.

Thus, the major product formed is the enone shown in the provided image. This is the result of the bromination followed by elimination yielding a conjugated enone.

Conclusion: The major product is the conjugated enone, which corresponds with the correct answer option provided.

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Important Questions from Organic Transformations

  1. The major products X and Y in the following reaction sequence are 

  2. The following conversion is an example of 

  3. The major product formed in the reaction given below is

  4. In the following reaction 

    the major product [X] is

  5. In the following reaction 

    the major product [X] is

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