Ni-Catalyzed Site-Selective Dicarboxylation of 1,3-Dienes with CO.

A site-selective catalytic incorporation of multiple CO molecules into 1,3-dienes en route to adipic acids is described. This protocol is characterized by its mild conditions, excellent chemo- and regioselectivity and ease of execution under CO (1 atm), including the use of bulk butadiene and/or isoprene feedstocks.

Nickel-Catalyzed CO Rearrangement of Enol Metal Carbonates for the Efficient Synthesis of β-Ketocarboxylic Acids.

4-Methylene-1,3-dioxolan-2-ones underwent oxidative addition of a Ni catalyst in the presence of Me Al(OMe), followed by a coupling reaction with alkynes, to form δ,ϵ-unsaturated β-ketocarboxylic acids with high regio- and stereoselectivity. The reaction proceeds by [1,3] rearrangement of an enol metal carbonate intermediate and the formal reinsertion of CO .

Efficient and selective formation of unsaturated carboxylic and phenylacetic acids from diketene.

A nickel catalyst promotes the multicomponent coupling reaction of diketene, an alkyne, and Me2Zn to provide 3-methylene-4-hexenoic acids in excellent yields. Under similar conditions, the combination of the nickel catalyst and Et2Al(OEt) promotes a cycloaddition reaction involving dimerization of an alkyne to furnish phenylacetic acids. In the presence of PPh3, a formal [2+2+1+1] cycloaddition reaction proceeds to afford regioisomeric phenylacetic acids via cleavage of the C=C bond.