Radical Conjugate Addition of Acylsilane Enabled by Synergistic
Photoredox and Lewis Acid Catalysis
A visible-light-induced acyl radical conjugate addition to
electron-deficient alkenes with acylsilane was realized by merging
photoredox and Lewis acid catalysis under mild reaction conditions.
Various tri- and tetra-substituted furans were obtained with good yield
(up to 97%) from α,β-unsaturated ketones. Based on the experimental
results and spectral analysis, a possible catalytic cycle involving
1,4-conjugate addition/ring-closure/arylation sequence was proposed.
Beyond that, 1,6-acyl radical conjugate addition to para-quinone
methides was also accomplished to deliver a series of α-aryl ketones by
using this synergistic catalysis protocol.