Organic Chemistry Practice Problems Pinacol Rearrangement Practice Problems Solution: When compound shown below is exposed to an acid, a...

Solution: When compound shown below is exposed to an acid, a molecule of water is eliminated, and a structural rearrangement ensues. The final product is a ketone with a molecular formula C18H18O. However, despite the fact that there are two –OH groups in the starting material, only one ketone is produced, with greater than 99% selectivity. Draw (a) the structure of that ketone and (b) the detailed mechanism that explains its formation. Then (c) provide a brief explanation why no other products are formed. Show all charges and intermediates, and use curved arrows to indicate the flow of electrons. Do not draw transition states.

Problem

When compound shown below is exposed to an acid, a molecule of water is eliminated, and a structural rearrangement ensues. The final product is a ketone with a molecular formula C18H18O. However, despite the fact that there are two –OH groups in the starting material, only one ketone is produced, with greater than 99% selectivity. Draw (a) the structure of that ketone and (b) the detailed mechanism that explains its formation. Then (c) provide a brief explanation why no other products are formed. Show all charges and intermediates, and use curved arrows to indicate the flow of electrons. Do not draw transition states.