Disclosed is method for increasing the efficiency of a dirhodium catalyst. The method includes providing a dirhodium catalyst, providing an organic ester, and contacting the dirhodium catalyst and the organic ester under conditions effective to increase the efficiency of the dirhodium catalyst. The organic ester is selected such that it is not a substrate for catalysis by the dirhodium catalyst. Dirhodium catalyst compositions which include a dirhodium catalyst and an organic ester are also disclosed. In these compositions, the organic ester is not a substrate for catalysis by the dirhodium catalyst. The method and compositions can be used in a number of reactions, including insertion reactions (e.g., C—H insertions, Si—H insertions, O—H insertions, and N—H insertions) cyclopropanation reactions, annulations (e.g., [3+2] annulations and [3+4] annulations), and ,-diarylalkanoate syntheses.