With Bases, Nucleophiles, and Reducing Agents

Nishiguchi, T. Yokijama, and M. Nitta, Chem. Letters, 1975,433. 

Vergnani, M. Karpf, L. Hoesch, and A. S. Dreiding, Helv. Chim. Acta, 1975,58,2524. 

The data is consistent with the initial formation of a cyclopropylcarbinyl cation which then undergoes rapid ring-opening to the allylcarbinyl cation from which the products are derived. 

Metallated methylenecyclobutane has been used as an isoprene equivalent in terpene synthesis. Methylenecyclobutene has been metallated with butyl-lithium and tetramethylethylenediamine. Reaction of the ambident anion (384) with electrophiles gives a mixture of positional isomers. The ratio of the isomers can be controlled by variation of solvent and temperature in this reaction and the cyclobutene ring in the products can then be opened thermally to dienes. This method has been applied to a synthesis of a component of the Ips confusus pheromone. Reaction of (384) with iso-valeraldehyde gave 30 % of the cyclobutene (385) which was isomerized to (386) by heating at 150°C. 

The general method of converting ketones into the corresponding a -unsaturated ketones by conversion of the ketones into the phenylselenoketones, followed by oxidation and elimination of benzeneselenic acid, has been applied to phenyl cyclobutyl ketone and 3-phenylcyclobutanone.  

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