Recent Developments in Enantioselective Nickel(II)-Catalyzed Conjugate Additions

During the last ten years, an important number of novel highly efficient asymmetric conjugate additions of various nucleophiles to numerous acceptor‐activated olefins have been developed on the basis of asymmetric nickel(II) catalysis by the very fact of the lower costs of nickel catalysts in comparison with other transition metals. These processes can be considered as one of the most powerful and reliable tools for the stereocontrolled formation of carbon‐carbon bonds. Importantly, a range of fascinating nickel‐catalyzed asymmetric domino reactions initiated by Michael additions has been successfully developed. The goal of this review is to collect the major developments in enantioselective nickel‐catalyzed conjugate additions reported since the beginning of 2004, well illustrating the power of these inexpensive and highly abundant catalysts to achieve functionalized chiral compounds to be applied as key intermediates in the synthesis of biologically interesting molecules including natural products. Abbreviations: Ac: acetyl; Acac: acetylacetone; Ar: aryl; BINAP: 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl; BINIM: binapthyldiimine; Bn: benzyl; Boc: tert‐butoxycarbonyl; Cbz: benzyloxycarbonyl; cod: cyclooctadiene; Cy: cyclohexyl; DBFOX: dibenzofurandiyloxazoline; DBU: 1,8‐diazabicyclo[5.4.0]undec‐7‐ene; de: diastereomeric excess; DME: dimethoxyethane; DMF: dimethylformamide; dr: diastereomeric ratio; ee: enantiomeric excess; ESI: electrospray ionization; Hex: hexyl; HFIP: hexafluoroisopropyl alcohol; HIPT: hexaisopropylterphenyl; HMPA: hexamethylphosphoramide; L: ligand; MS: mass spectroscopy; MTBE: methyl tert‐butyl ether; Naph: naphthyl; Pent: pentyl; PFP: pentafluorophenol; Pin: pinacolato; PMB: p‐methoxybenzyl; QN: quinolyl; r.t.: room temperature; TADDOL: α,α,α′,α′‐tetraphenyl‐2,2‐dimethyl‐1,3‐dioxolane‐4,5‐dimethanol; TEA: trimethylamine; Tf: trifluoromethanesulfonyl; THF: tetrahydrofuran; TMP: 2,2,6,6‐tetramethylpiperidide; TMS: trimethylsilyl; Tol: tolyl; Ts: 4‐toluenesulfonyl (tosyl).