[3+2] Cycloaddition Reaction of Cyclopropyl Ketones with Alkynes Catalyzed by Nickel/Dimethylaluminum Chloride

Abstract

Nick and Al join forces: The nickel‐catalyzed [3+2] cycloaddition between the title compounds gives cyclopentene derivatives in the presence of Me2AlCl. The organoaluminum reagent activates the carbonyl group of the cyclopropyl ketone through coordination of the oxygen atom to the aluminum, and stabilizes the reaction intermediate by the coordination of the chloride to nickel. cod=1,5‐cyclooctadiene, THF=tetrahydrofuran.

The roles of Lewis acidic additives in organotransition metal catalysis

“…2 ) in combination with Ni(COD) 2 and B(C 6 F 5 ) 3 as the Lewis acid cocatalyst (Scheme 4). 21 Other C-C bonds can be activated such as in anhydrides, 22 cyclopropanes, 23 and esters. 24 In the latter example, the reaction of arylnitrile 12 with 2-butyne (13) and catalytic Ni(COD) 2 /P(CH 2 Ph) 3 /MAD (MAD = methylaluminum bis(2,6-di-t-butyl-4-methylphenoxide)) results in sequential C-C bond activation events resulting in formation of coumarin 14 and elimination of arylnitrile 15.…”

Ring-opening hydroarylation of monosubstituted cyclopropanes enabled by hexafluoroisopropanol

“…Generally speaking, the reactivity of monosubstituted cyclopropanes is much less developed than for donor–acceptor cyclopropanes. Existing ring-opening reactions include oxidative addition into C–C bonds with transition metals, 6 – 8 oxidative 1,3-difunctionalization, 9 frustrated Lewis pairs, 10 , 11 or addition of strong nucleophiles 12 – 14 and mineral acids. 15 One-pot iodination/alkylation procedures are also known.…”

“Cut and Sew” Transformations via Transition-Metal-Catalyzed Carbon–Carbon Bond Activation

“…31 Me 2 AlCl was employed as a Lewis acid cocatalyst in addition to the Ni catalyst (Scheme 15). The mechanism was proposed to initiate from coordination of the alkyne and ketone moieties to Ni.…”