Trifluoromethyl-substituted indenyl rhodium and iridium complexes are highly selective catalysts for directed hydroboration reactions
Rhodium and iridium catalysts containing trifluoromethyl-substituted indenyl ligands (Ind'MCod, Ind' = C9H7, (1-CF3)C9H6, (2-CF3)C9H6, (1,3-CF3)2C9H5) have been developed for the directed hydroboration of 4-(benzyloxy)cyclohexene to cis-3-(benzyloxy)cyclohexanol. Compared to unsubstituted complexes, trifluoromethyl substitution yields a 3-10% increase in selectivity which is attributed to the strong electron-withdrawing effect of the trifluoromethyl group. Rhodium complexes give selectivities of 74-84%, and iridium complexes give high levels of selectivity (93-98%).
Brinkman
JA
Department of Chemistry, Seton Hall University, South Orange, New Jersey 07079, USA.
Nguyen
TT
Sowa
JR