Identify the starting material ( ? ) in the given reaction sequence: ? [ (ii) Vinyl lithium, then H ₃ O ^+, ] (i) CuCN

Step-by-step solution

The given reaction sequence involves two main steps to form phenyl vinyl ketone. The starting material reacts with CuCN . Among the given options, the benzenediazonium cation (Option A) undergoes the Sandmeyer reaction with CuCN to form benzonitrile ( Ph-CN ). Ph-N ₂^+ + CuCN Ph-CN + N ₂ Benzonitrile reacts with vinyl lithium ( CH ₂ =CH-Li ). The nucleophilic vinyl group attacks the electrophilic carbon of the nitrile, forming an imine salt intermediate. Ph-CN + CH ₂ =CH-Li Ph-C(=NLi)-CH=CH ₂ Acidic hydrolysis ( H