Abstract
Despite their unique potential as rare 1,1-dipole synthons, allyl sulfones are rarely
used in target-oriented syntheses, likely due to the lack of a general catalytic method
for their branch-selective allylic substitution. Herein, we identified allyl 4-chlorophenyl
sulfone as a versatile linchpin for both base-mediated α-derivatization and subsequent
cobalt-catalyzed allylic substitution. The sequential transformations allow for highly
regioselective access to branched allylic substitution products with a variety of
aliphatic side chains. The photoredox-enabled cobalt catalysis is indispensable
for achieving high yields and regioselectivity for the desulfonylative substitution
in contrast to traditional metal-catalyzed protocols, which lead to inferior outcomes
in the corresponding transformations.
Key words
cobalt catalysis - photoredox catalysis - metallaphotoredox - allylation - sulfones
- regioselectivity