JEE Main Chemistry question

The product obtained in the reaction of a highly branched tetramethyl-substituted ketone with 1. (CH₃)₂CHMgBr 2. H⁺ is

(A)The expected tertiary alcohol from simple Grignard addition
(B)An alkene + a secondary alcohol, from a competing reduction (hydride transfer) pathway due to severe steric hindranceCorrect
(C)No reaction
(D)A rearranged ketone

Answer: (B)

Solution

When the ketone carbonyl is extremely hindered (flanked by bulky tert-butyl/isopropyl-type groups), a Grignard reagent bearing a β-hydrogen (such as isopropylmagnesium bromide) can act as a hydride donor instead of a simple nucleophile — this competing

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Question ID VK-149359