The reaction of an alkyl nickel acylate complex with a variety of mono- and
disubstituted acetylene derivatives was investigated. Depending upon the s
ubstitution pattern and the reaction time, the reaction product can be a 1,
4-diketone, a cyclopentenone, or a gamma-lactone, but only when the reactio
n is performed under an Ar atmosphere. When a CO atmosphere is used, no rea
ction occurs. The mechanism for formation of each of these compounds is dis
cussed.