See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the substrate: The starting material is a bicyclic compound resembling a dihydronaphthalene or indene derivative with an OMe group attached to a vinyl carbon (enol ether type double bond) and another alkene that is part of the ring system. Step 2 - Principle of electrophilic ozonolysis selectivity: Ozone (O3) is an electrophile. It preferentially reacts with the more electron-rich (more nucleophilic) double bond. An enol ether double bond (C=C with OMe substituent) is significantly more electron-rich than a simple alkene because the oxygen lone pairs donate into the pi system via resonance, making it far more reactive toward electrophilic ozone. Therefore, ozone selectively cleaves the enol ether double bond (the OMe-substituted alkene) over the simple alkene. Step 3 - Ozonolysis of the enol ether: Ozonolysis of a vinyl ether (enol ether) under reductive workup (Me2S) gives an ester (methyl ester, CO2Me) from the OMe-bearing carbon and an aldehyde from the other carbon of the double bond. The OMe carbon becomes CO2Me because ozonolysis of R-CH=C(OMe)-R' with reductive workup gives an aldehyde/ketone from one fragment and a methyl formate/ester from the OMe-bearing carbon. Step 4 - NaBH4 reduction: NaBH4 is added after reductive ozonolysis workup. NaBH4 selectively reduces aldehydes over esters. The aldehyde generated from ozonolysis is reduced to a primary alcohol (CH2OH), while the ester (CO2Me) remains intact. Step 5 - Product identification: The product P contains the bicyclic framework with a CO2Me group (from the OMe-bearing carbon of the cleaved double bond, now part of the ring as a pendant ester) and a CH2OH group (aldehyde reduced by NaBH4). This corresponds exactly to option (b): a bicyclic indane-type structure with CO2Me and OH (CH2OH) substituents. Step 6 - Why other options fail: - Option (a) would be the product before NaBH4 reduction (aldehyde not yet reduced); since NaBH4 is applied, the CHO becomes CH2OH, ruling out (a). - Option (c) is a linear chain product, not consistent with selective ozonolysis of the enol ether in a bicyclic system. - Option (d) is also a linear chain with an alcohol, not matching the bicyclic framework. Therefore, the correct answer is B.