Figure 5. Fe(III) salts expand the breadth of cross-nucleophile coupling reactions.
(A) Comparison of reactivity using Cu(II) and Fe(III) salts. Reaction conditions for Cu(II) mediated couplings: Cu(OTf)2 (2.5 equiv), Na3PO4 (3.0 equiv), i-PrCN (5.5 equiv), nucleophile (3.0 equiv), and carboxylic acid 1 (0.1 mmol) in CH2Cl2 (0.10M) setup under inert atmosphere and irradiated with a 427 nm blue Kessil Lamp at RT for 24 h. Yields were determined by 1H NMR analysis of the crude reaction mixture using 1-methylnaphthalene as an internal standard. Reaction conditions for Fe(III)-mediated couplings are reported in Figures 2 and 3.
(B) Proposed roles of Fe(III) in the C–C bond-forming reaction.