Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated ketones with DIFLUORPHOS and SYNPHOS analogues.

Applications of electron-deficient DIFLUORPHOS and SYNPHOS analogues in the rhodium-catalyzed asymmetric conjugate addition of boronic acids to α,β-unsaturated ketones afford the 1,4-addition adducts in yields up to 92% and with 99% ee. Particularly, a Rh-catalyzed asymmetric 1,4-addition of arylboronic acids to nonsubstituted maleimide substrates using the (R)-3,5-diCF(3)-SYNPHOS ligand is also reported. This protocol provides access to various enantioenriched 3-substituted succinimide units of biological interest, in high yields and good to excellent ee up to 93%, which could be upgraded up to 99% ee, after a single crystallization.