Consider the given reaction sequence. Identify the structure of the major product Z .

Step-by-step solution

The reaction sequence involves the following steps: 1. Protection: The starting material, 5-hydroxy-2-pentanone, reacts with 1,3-propanediol in the presence of an acid catalyst ( H ^+ ). This selectively protects the more reactive ketone group as a cyclic ketal (1,3-dioxane derivative), while the primary alcohol remains unaffected. 2. Oxidation: Pyridinium chlorochromate (PCC) oxidizes the primary alcohol group to an aldehyde. The ketal group is stable under these mildly acidic, non-aqueous conditions. 3. Wittig Re