Resolution of BIPHEP on Rh with a chiral diene auxiliary

Resolution of the atropisomeric chiral BIPHEP ligand on Rh has been achieved with the aid of 2-(4-tert-butyl-phenyl)-8-methoxy-1,8-dimethyl-bicyclo[2.2.2]octa-2,5-diene, a chiral chelating diene ligand. The diene complex 3 containing an (S)-BIPHEP ligand was found to be configurationally stable in CDCl3 solution at RT. Conversion of the diene complex 3 to a dicarbonyl Rh complex 4 that had a barrier of 25.0 kcal/mol for atropisomerization of the BIPHEP ligand. Preliminary studies of the use of the resolved complex 3 for catalysis are presented.