Dynamic Kinetic Resolution in Rhodium-Catalyzed Asymmetric Arylation of Phospholene Oxides.

The reaction of 2,5-dihydro-1H-phosphole 1-oxide 1 with ArB(pin) 3 in the presence of a chiral (R)-segphos-rhodium catalyst under highly basic conditions (10 equiv of KOH) gave high yields of (1S,3S)-3-arylphospholane 1-oxide 4 with high diastereoselectivity as well as high enantioselectivity. Equilibration of 1 with its 2,3-dihydro isomer 2, which is chiral and racemic, by base-catalyzed olefin isomerization followed by kinetic resolution of 2 with the chiral rhodium catalyst realized the present dynamic kinetic resolution.