See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1: Identify the substrate. The compound is an octalin (1,2,3,4,4a,5,6,7,8,8a-decahydronaphthalene) with a double bond between the two ring-junction carbons (C4a–C8a). There is a methyl group (on a bold/wedge bond) at one ring-junction carbon and an ethyl group (on a bold/wedge bond) at the other ring-junction carbon. Step 2: Identify the reaction. OsO4 followed by NaHSO3 is a syn-dihydroxylation reaction. OsO4 adds across the double bond in a concerted, syn (same-face) fashion to give a cis-diol after workup with NaHSO3. Step 3: Determine the faces of attack. The double bond is between C4a and C8a. OsO4 can attack from either the top face or the bottom face of the double bond. The existing substituents (methyl at C4a on a wedge = above the plane, ethyl at C8a on a wedge = above the plane) define the two faces. Attack from the top (same side as methyl and ethyl) gives one syn-diol, and attack from the bottom (opposite side) gives another syn-diol. Step 4: Consider the stereochemical outcomes. Since both substituents are on the same face (both on wedge bonds = both above the plane), the two faces of the double bond are diastereotopic. Top-face attack gives one diastereomeric product, and bottom-face attack gives another diastereomeric product. These two products are diastereomers of each other, not enantiomers, because the molecule already has stereocenters that make the two faces non-equivalent. Step 5: Count distinct products. Since OsO4 is achiral but the substrate is chiral (both existing stereocenters are defined), top-face and bottom-face attacks give two distinct diastereomeric diol products. No racemic mixture issue arises here beyond these two diastereomers because the starting material is a single enantiomer (defined stereochemistry at both ring junctions). Step 6: Why other options fail. Option (a) 10 and (c) 3 and (d) 4 are incorrect because there are only two faces of the double bond, and syn-dihydroxylation on each face gives exactly one product per face, totaling 2 products. Therefore, the correct answer is B.