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JEE Advanced · 2016 · 22 May 2016 · Paper 2 · Chapter_pending

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The major product of the following reaction sequence is
  1. (A)(see structure)
    ✓ Correct
  2. (B)(see structure)
  3. (C)(see structure)
  4. (D)(see structure)

Answer: (A)

Solution

The Grignard reagent (phenylmagnesium bromide) adds to the ketone carbonyl to form a tertiary alcohol. The acidic workup protonates the alkoxide. The product is a cyclic acetal/ketal structure where the tertiary alcohol carbon is incorporated into the ring system with the two oxygen atoms from the original diol protecting group.

JEE Advanced · 2016 · 22 May 2016 · Paper 2 · Single correct option

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