In rhodium catalysed borylation of cyclic olefins, the synergy between bidentate NHC ligands, that modify cationic Rh(I) species, and the use of non-polar solvents, such as cyclohexane, is the key factor to favour a less energetically demanding route towards the formation of diborated products versus allyl boronate esters.
![Rhodium–NHC complexes mediate diboration versus dehydrogenative borylation of cyclic olefins: A theoretical explanation](https://www.iciq.org/wp-content/uploads/2014/03/RhodiumNHC-complexes-mediate_746.gif)