Rhodium-Catalyzed Asymmetric Arylation of Allyl Sulfones under the Conditions of Isomerization into Alkenyl Sulfones

The reaction of 3-sulfolene with arylboronic acids in the presence of a chiral diene-rhodium catalyst under highly basic conditions (10 equiv of KOH),gave high yields of 3-arylsulfolanes with high enantioselectivity, where 3-sulfoleneis in equilibration with 2-sulfolene by base-catalyzed isomerization and the more reactive 2-sulfolene undergoes the rhodium-catalyzed asymmetric arylation.