Synthesis and rearrangement of [1, 1′-bicyclobutyl]-1-ols and spiro [3.4] octan-5-ols: a general access to bicyclo [3.3. 0] octenes (hexahydropentalenes)
Several new Grignard reagents based on substituted cyclobutanes have been generated and added to cyclobutanones to yield mono-to trimethylated [1, 1′-bicyclobutyl]-1-ols. Mono-to trimethylated spiro [3.4] octan-5-ols have been prepared from the parent ketone via alkylation and/or addition reactions. Upon treatment with acid, all [1, 1′-bicyclobutyl]-1-ols and spiro [3.4] octan-5-ols rearrange to yield a single bicyclo [3.3. 0] octene.