# Does the Oxy or Alkoxy Claisen Rearrangement Exist?

@Waylander's cogent Comment to the query of @Random Guy inspired me to post a problem in synthesis to test a question I have pondered for some time. The activation energy (AE) for the Cope rearrangement of 1 is higher than that for the rearrangement of oxy-Cope precursor 2, whose AE is higher than that of the alkoxy-Cope precursor 3. The AE for the Claisen rearrangement of 4 is lower than that for the Cope rearrangement of 1. Can the analogs 5 (R = alkyl, silyl) and 6 be prepared to test whether or not a Claisen rearrangement occurs? The observant reader will recognize 6 as the 1,2-addition product of the enolate of acetaldehyde (or similar enolate) to methyl vinyl ketone (MVK). Does a Michael addition occur by cleavage of 6 with subsequent 1,4-addition or does a Claisen rearrangement intercede? The stereochemistry of the rearrangement of 7 may prove insightful. Would the rearrangement of 9, enolate stereochemistry notwithstanding, be the same or different from that of a Michael addition?

Design a synthesis of 5 or a precursor to 6 taking any liberties with substitution patterns. If you are truly ambitious, go for 7 or a precusor to 9. Feel free to utilize (Z)-and/or (E)-double bonds in 7 and 9.

I am looking for an enterprising young chemist to solve this problem.

Having had no responses to this post, I thought I would offer a scheme in an effort to answer the question about the existence of the oxy Claisen rearrangement. α-Diketone 1[1] was chosen as a starting material owing to the equivalency of the two carbonyls. Selective monoketalization of α-diketone 1 with β-bromoethanol affords cyclohexanone 2. Over ketalization is unlikely owing to steric considerations. Wittig reactions of the type 2 $$\rightarrow$$ 3 have been conducted successfully.[2]