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21.1.6.8.4 Method 4: Copper(I)-Catalyzed Amidation

DOI: 10.1055/sos-SD-021-00136

Li, W-R.Science of Synthesis, (200521221.

A copper(I)-mediated enamide formation technique can be used to synthesize highly unsaturated enamide side chains of natural products. The reaction occurs at moderate temperatures and the method is suitable for the attachment of potentially labile enamide chains to complex substrates.[‌212‌] In the amidation reaction, vinyl iodides are more reactive than vinyl bromides as substrates; however, in the coupling reaction with benzamide, when an excess of (E)-1-iodohept-1-ene (2.2 equiv) and cesium carbonate (2.0 equiv) are used, the enamide 173 (77% yield) is the sole product (Scheme 41). N,N-Divinyl amide products do not form in this reaction and the excess iodoalkene (70%) is recovered. Reaction of conjugated amide 174 under similar conditions gives N-substituted amide 175 in 69% yield. In addition, the copper(I)-catalyzed vinylic substitution protocol, which complements related CN bond-formation methodologies, follows a stereocontrolled pathway.

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