[scientific]

Cannot for the life of me figure out what's wrong. Please find attached images.

3-methylcyclepentene, methyl group coming out of the page, reacted with O₃, then worked with Zn/H₂O

What would the product be? The top or bottom? My notes say that the absolute configuration of chiral center is preserved, but wouldn't that be the bottom? My book says it's the top product, but i don't understand--isn't the configuration around the chiral carbon changed then?

Thanks!

[Dan]

My notes say that the absolute configuration of chiral center is preserved, but wouldn't that be the bottom? My book says it's the top product, but i don't understand--isn't the configuration around the chiral carbon changed then?

Number the carbon atoms in the starting material and the corresponding carbon atoms in the product. The product molecule has been rotated relative to the starting material - it's not as simple as looking to see whether the Me is up or down in the product, you need to consider 3D rotation.

Draw the product in the same orientation/conformation as the starting material, then rotate it to match the orientation of the answer. Alternatively, draw the product in the same orientation as the starting material, assign the stereochemistry R/S, assign the stereochemistry R/S in the two answer options and choose the correct one.