Identify the reactant that yields the given product through the following sequence of reactions: (i) HO - CH ₂ CH ₂- OH , catalytic H ⁺ (ii) Mg , THF ; then H ₂ C = O ; then H ₃ O ⁺ (iii) H ₃ O ⁺ , heat Product:

Step-by-step solution

The product is a cyclic hemiacetal containing a 6-membered ring fused to a benzene ring. The hemiacetal carbon is bonded to a methyl group, indicating it is derived from the intramolecular cyclization of a hydroxyl group with a methyl ketone. Evaluating the reaction sequence for the reactant in Option C gives the desired product. In the first step, the ketone group -COCH₃ of 1-(2-(bromomethyl)phenyl)ethan-1-one is protected as a cyclic ketal using HO-CH₂CH₂-OH and catalytic H^+ . The -CH₂Br group remains unaffected