MECHANISTIC STUDY OF THE RHODIUM(I)-CATALYZED HYDROBORATION REACTION

The objective of this study has been to elucidate the mechanism of the rhodium(I)-catalyzed hydroboration process. Evidence that the reaction proceeds through a multistep pathway analogous to that of transition metal catalyzed olefin hydrogenation is presented. Deuterium labeling experiments reveal reversible elementary steps in the catalytic cycle; the level of reversibility is found to be substrate-dependent. Catalyst contamination through contact with adventitious oxidants has a pronounced effect on the reaction and appears to be the source of reported disparities involving product regioselection and deuterium labeling experiments.