Question

The major products of following reaction sequence are :

• A. I =
• B. I =
• C. III =
• D. III =

Answer 1

Answer: (B), (D)

(B), (D)

Answer 2

The reaction sequence involves three steps:

Step 1: Pinacol Rearrangement

The starting material undergoes a pinacol rearrangement in the presence of H2SO4. This involves protonation of one of the hydroxyl groups, followed by the migration of a group from the adjacent carbon, leading to ring expansion and the formation of a ketone (I).

Step 2: Reduction with LiAlH4

The ketone (I) is then reduced by LiAlH4 to form a secondary alcohol (II).

Step 3: Acid-Catalyzed Dehydration

Finally, the alcohol (II) undergoes acid-catalyzed dehydration, leading to the formation of an alkene (III). The major product is the more stable alkene, which has the double bond conjugated with the phenyl rings.

Therefore, the major products are I as shown in option (B) and III as shown in option (D).