Reaction of Na(RCO)Fe(CO) < inf > 4 < /inf > with CuCl or I < inf > 2 < /inf > : Synthetic and Mechanistic Studies of the Formation of 1,2-Diketones in a Novel Double-Carbonylation Process

Abstract

Reaction of Na(RCO)Fe(CO)4 with CuCl at 25 °C in THF leads to the formation of 1,2-diketones, RCOCOR (70–90% yield). The reaction was carried out in the presence of methyl acrylate in order to get information about possible intermediates. In these runs, the 1,2-diketones (20–28%) and acyllactones (35–52%), derived from two alkyl and two CO groups and one acrylate moiety, are formed. The reaction of I2 with Na(RCO)Fe(CO)4 was investigated in order to compare the reactivities with the Na(RCO)Fe(CO)4/CuCl system. In this case, the reaction is not clear and the 1,2-diketone (32%), dialkyl ketone (8%), and RCOOH (29%) (R = n-octyl) are obtained. When the reaction of Na(RCO)Fe(CO)4 was carried out with I2 in the presence of methyl acrylate, the acyllactones (19–21%), 1,2-diketones (16–18%), dialkyl ketones (4–5%), and RCOOH (6–7%) are isolated. It is proposed that the formation of 1,2-diketone takes place through the decomposition of Cu(RCO)Fe(CO)4 or I(RCO)Fe(CO)4 to RCOFe(CO)4 followed by the formation of η2 complexes of 1,2-diketones as fleeting intermediates. © 1993, American Chemical Society. All rights reserved.