Cyclobutanol and Cyclobutanone Derivatives

Reactions Involving p-Carbon Elimination of Transition Metal Cyclobutanolates 

Transition metal alkoxides of tert-cyclobutanols undergo ring opening by P-carbon elimination to generate ketones that are metalated at the y-position these can be utilized in many functionalization reactions. Palladium, rhodium, and nickel have been the most studied metals in these transformations. Useful transition metal cyclobutanolates are generated from either cyclobutanones or cyclobutanols. 

3-Monosubstituted cyclobutanones reacted with arylboronic acids in the presence of a Rh(I)-P(f-Bu)3 catalyst to afford butyrophenone derivatives by the addition of an arylrhodium(I) species to the carbonyl group, followed by ring opening of the resulting rhodium(I) cyclobutanolate by P-carbon elimination 

The alkylrhodium(I) species formed by ring opening of 3-(2-silylphenyl)-cyclobutanol 44 underwent a 1,4-rhodium/silicon exchange to generate 

Some cyclobutanones were amenable to asymmetric reaction, in which a BINOL (l,l -bi-2-naphthol)-derived phosphoramidite worked as an excellent 

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Both cyclobutanones and the tertiary cyclobutanols derived from them behave as intramolecular alkylating reagents towards 0-substituted aromatic rings under 4-TsOH catalysis yielding cyclobuta[c]chromans 23. The use of an equimolar amount of 4-TsOH results in subsequent fission of the cyclobutane ring and the formation of chromenes <04T449>. 

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