Regioselective Nickel‐Catalyzed Reductive Couplings of Enones and Allenes

Abstract

Alkenes made easy: In a complement to coupling processes of terminal alkynes, the reductive coupling of enones and allenes provides access to conjugate addition products that possess a 1,1‐disubstituted alkene (see scheme; cod=1,5‐cyclooctadiene). The solvent composition and reducing agent must be carefully matched to allow high levels of regioselectivity to be observed.

Iridium-Catalyzed Intramolecular β-C–H Alkenylation of Ketones with Alkynes via a Hydride-Transfer Approach

“…The subsequent conjugate addition and α-protonation form the β-C–C bond and deliver the desired product with the regeneration of the Ir­(I) catalyst. Alternatively, as described in path b , enyne cyclometalation could take place to give an Ir­(III) metallacycle and forge the β-C–C bond (intermediate E ) . The following C–H reductive elimination and α-protonation can also give the desired product.…”

Hydroarylation of N‐Allenyl Derivatives Catalyzed by Copper**

“…Hydrofunctionalization of allenes mainly allowed the selective formation of C–N, C–O, and C–C bond. [ 2,3,5–8 ] The latter being performed through the addition of pronucleophiles such as malonates, [ 9–12 ] nitriles, [ 13–16 ] alkynes, [ 17–19 ] alkenes, [ 20–22 ] and aryl derivatives. The reaction of aromatic compounds with allenes, known as hydroarylation reaction, consists of adding an aryl moiety to a C–C double bond and constitutes a powerful tool to form a Csp 3 –Csp 2 bond in a regio‐ and stereoselective manner.…”

Metal-Catalyzed Intermolecular Hydrofunctionalization of Allenes: Easy Access to Allylic Structures via the Selective Formation of C–N, C–C, and C–O Bonds

“…235 The group of Montgomery published in 2010 the regioselective nickel catalyzed reductive coupling of various enones with mono-and 1,3-disubstituted allenes (Scheme 110). 236 This reaction affords the possibility to synthesize γ,δunsaturated carbonyl compounds with trisubstituted alkenes.…”