Consider the following reaction sequence: 3-phenylprop-1-ene [ (ii) H ₂ O ₂, OH ^-] (i) BH ₃ THF A PCC B The major product 'B' is:

Step-by-step solution

Hydroboration-oxidation of 3-phenylprop-1-ene proceeds via anti-Markovnikov addition of water to the double bond, yielding a primary alcohol, 3-phenylpropan-1-ol (Product A). The presence of the phenyl ring does not alter the regioselectivity of this concerted mechanism. Subsequent oxidation of this primary alcohol with Pyridinium Chlorochromate (PCC), a mild oxidizing agent, selectively yields an aldehyde without over-oxidizing it to a carboxylic acid. Thus, the final product B is 3-phenylpropanal. Answer: 3-pheny