Highly enantioselective synthesis of pseudo-C2-symmetric axially chiral biaryl diphosphines via rhodium-catalyzed double [2+2+2] cycloaddition

Cationic rhodium complexes based on (R)-BINAP catalyze the sequential double [2 + 2 + 2] cycloaddition between 1,4-bis(diphenylphosphinoyl)buta-1,3-diyne and an internal 2,n-diyne followed by its terminal counterpart in an operationally straightforward procedure to afford pseudo-C-2-symmetric axially chiral biaryl diphosphines in good yield and with exceptionally high enantioselectivity.