Asymmetric Rh(I)-Catalyzed Addition of MIDA Boronates to N-tert-Butanesulfinyl Aldimines: Development and Comparison to Trifluoroborates

The Rh(I)-catalyzed addition of alkenyl and aryl MIDA boronates to N-tert-butanesulfinyl aromatic and aliphatic imines proceeds in good yields (up to 99%) and with very high selectivity (98:2 to >99:1). In comparison to trifluoroborates, higher yields and selectivities are observed for the addition to N-tert-butanesulfinyl aromatic imines. This new method expands upon the versatility of the Rh(I)-catalyzed addition of boron reagents to imines, thereby further enabling the synthesis of chiral α-branched amines.