Influence of the stereochemistry on the 1,2-dialkenylcyclobutanols behaviour : oxy-cope versus retro-ene rearrangements

✍ Scribed by J.P. Barnier; J. Ollivier; J. Salaun

• Book ID: 104232884
• Publisher: Elsevier Science
• Year: 1989
• Tongue: French
• Weight: 296 KB
• Volume: 30
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)80441-x

✦ Synopsis

From cyclobutanones Sa-j,ten 1,2-divinylcyclobutanot la-j were prepared. A stereochemical effect was clearly evidenced : while trans 1,2-divinylcyclobutanols underwent a retro-ene ring opening, the cis isomers underwent an oxy-Cope ring enlargement. It is well known that cis 1,2-divinylcyclobutanes undergo thermal [3.3] sigmatropic rearrangement into cis. cis l,%cyclooctadienes (Cope rearrangement) 1 while the corresponding trans isomers react predominantly via Il.31 shift process to provide 4-vinylcyclohexenes 2. On the other hand, it has been recently claimed that both cis and trans 1,2dialkenylcyclobutanols 1 undergo upon treatment with potassium hydride (KH), anionic oxy-Cope C4 -> Cg ring expansion to give 4-cycloocten-l-ones 2 in good yields 3, opening up new ways to cyclooctanoid terpenes such as poitediol or dactyl01 4. No products resulting from [1.3] rearrangements were detected in these reactions 3.