Photopromoted carbonylation of bromobenzene under ambient conditions

The photopromoted carbonylation of bromobenzene with carbon monoxide catalyzed by inexpensive commercially available cobalt salts [Co(OAc)2, CoCl2] was carried out under ambient conditions. The results revealed that methyl benzoate was produced in the presence of basic additives (CH3ONa, NaOAc or (n-C4H9)3N). The catalytic activity of Co(OAc)2 was higher than that of CoCl2. Furthermore, the activity of the carbonylation was greatly improved by addition of acetophenone, e.g. both the yield and selectivity of the ester were increased from 47% to 91% with Co(OAc)2 as catalyst and CH3ONa as additive, while the yield of by-product benzene from hydrodehalogenation of bromobenzene decreased from 32% to 8%.