Question

A cyclopropyl ether ketone is treated with $\text{H}_2\text{O}^{18}$ in the presence of acid. Which of the following is the major product?

(Image of a cyclopropyl ether ketone reacting with $\text{H}_2\text{O}^{18}$ and acid to form several possible products labeled A, B, C, and D.)

• A. Product A
• B. Product B
• C. Product C
• D. Product D

Answer 1

Answer: (A)

Product A

Answer 2

The reaction involves the acid-catalyzed hydrolysis of a cyclopropyl ether ketone with heavy water ($\text{H}_2\text{O}^{18}$). The strained cyclopropane ring and the ether linkage are cleaved. Protonation of the ether oxygen activates the ring for nucleophilic attack by water. The mechanism involves ring opening, likely forming a carbocation intermediate, followed by attack by $\text{H}_2\text{O}^{18}$. Rearrangements occur, leading to the incorporation of $\text{O}^{18}$ into the molecule, specifically at the aldehyde group in Product A, which is a $\gamma$-ketoaldehyde.