ChemInform Abstract: Nickel‐Catalyzed Reductive Conjugate Addition to Enones via Allylnickel Intermediates.

Abstract

Nickel-Catalyzed Reductive Conjugate Addition to Enones via Allylnickel Intermediates. -In comparison to related copper-catalyzed procedures the presented protocol utilizes readily accessible haloarenes instead of nucleophilic aryl reagents. A wide variety of functional groups is tolerated. From a mechanistic point of view these are the first examples for a catalytic reductive conjugate addition of organic halides via allylnickel intermediates. -(SHRESTHA, R.; DORN, S. C. M.; WEIX*, D. J.; J. Am. Chem. Soc. 135 (2013) 2, 751-762, http://dx.doi.org/10.1021/ja309176h ; Dep. Chem., Univ. Rochester, Rochester, NY 14627, USA; Eng.) -Nuesgen 33-036

Selective Cross-Coupling of Organic Halides with Allylic Acetates

“…Kishi has reported that neocuproine ( L4 ) nickel complexes are slow to dimerize aryl halides 23 and we have also found that neocuproine was a selective ligand for the reductive conjugate addition of aryl and vinyl halides with enones, which we propose involves allylnickel intermediates. 24 Indeed, L4 formed a highly selective catalyst for the cross-coupling of 2-bromocyclohexenone with the branched allylic acetate 2c (entry 3). The results appear related to sterics because the unsubstituted 1,10-phenanthroline provided poor results (entry 4).…”