Carbonylative cyclization of iodoarenes and iodoalkenes containing a p
roximal enolate precursor can selectively provide either cyclic ketone
s or lactones in the presence of Ni or Cu catalysts via trapping of pu
tative acylmetal derivatives with C-or O-enolates, respectively; the r
ing size and regioselectivity of the reaction may be predicted based o
n two generalizations derived from the recently developed correspondin
g Pd-catalyzed reaction. (C) 1998 Elsevier Science Ltd. All rights res
erved.