Frontalin is an aggregation pheromone that can be synthesized via the acid-catalyzed cyclization of an acyclic precursor. Based on the equilibrium shown below, identify the correct structure of this open-chain precursor.

Step-by-step solution

To find the open-chain precursor of Frontalin, we need to perform a retro-acetalization (hydrolysis) on its bicyclic ketal structure. 1. Analyze the structure of Frontalin: Frontalin is a bicyclic ketal with the IUPAC name 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane. Its molecular formula is C₈H₁₄O₂ . The structure consists of a 6-membered ring and a 5-membered ring sharing a common C-C-O-C framework. The key functional group is the ketal carbon, which is bonded to two oxygen atoms. 2. Hydrolysis of the ketal: The r