The ring opening of enantiomerically pure 3, 4-dimethyl-2, 5-diphenyl-1, 3, 2- oxazaphospholidine-2-borane (1) with a variety of bulky aryllithium reagents was studied. Our results are not in total agreement with those obtained by others. In fact, several 2, 6- disubstituted aryl groups were successfully appended to the phosphorus atom, furnishing the corresponding (N-ephedrino) phosphine boranes 2a-g with dr> 99: 1. However, when ...