An asymmetric three-component
carbosulfonylation of
alkenes is
presented here. The reaction, involving the simultaneous formation
of a C–C and a C–S bond across the π-system, uses
a dual nickel/photoredox catalytic system to produce both β-aryl
and β-alkenyl sulfones in high yields and with excellent levels
of stereocontrol (up to 99:1 er). This protocol exhibits a broad substrate
scope and excellent functional group tolerance and its synthetic potential
has been demonstrated by successful applications toward pharmacologically
relevant molecules. A broad array of control experiments supports
the involvement of a secondary alkyl radical intermediate generated
through radical addition of a sulfonyl radical to the double bond.
Moreover, stoichiometric and cross-over experiments further suggest
an underlying Ni(0)/Ni(I)/Ni(III) pathway operative in these transformations.