Nickel-catalyzed Reactions between Enone and Two Ethylenes

Abstract

In the presence of a catalytic amount of Ni(cod)2 and PCy3, the reaction of (E)-1-phenylbut-2-en-1-one (1a) with ethylene occurred to give three-component addition products, 1,6-enone 2a and 1,5-diketone 4a. The reaction of an enone with two ethylenes gave 2a. The reaction of two enones with an ethylene gave 4a. On the other hand, 2-methyl-1-phenylprop-2-en-1-one (1b) reacted with two ethylenes selectively to give a mixture of 2b and 3b. The reaction might proceed via oxidative cyclization of an enone and an ethylene with nickel(0).

Development and Mechanistic Studies of (E)-Selective Isomerization/Tandem Hydroarylation Reactions of Alkenes with a Nickel(0)/Phosphine Catalyst

“…We found the transition state TS1 α – β′ , which a hydrogen atom at the α-position of 1d is transferred to the β-position of another alkene coordinated to the nickel center. The intermolecular hydrogen shift, which includes a concerted multiple-bond rearrangement on the nickel center, can be classified as a mechanism analogous to ligand-to-ligand hydrogen transfer (LLHT) . Although the Gibbs activation energy of TS1 α – β′ was higher than those of the oxidative addition mechanism ( TS1 α – β′ , Δ G = +32.3 kcal/mol; TS1 - E or Z , Δ G < +18.0 kcal/mol), the corresponding enthalpy was lower than those of TS1 - E or Z ( TS1 α – β′ , Δ H = +15.8 kcal/mol; TS1 -E or Z, Δ H > +17.2 kcal/mol).…”

Nickel-catalyzed reactions of enone with ethylene

“…We, thus, investigated the reactivity of (E)-1-phenylbut-2-en-1-one (1) with ethylene in the presence of Ni(0) catalyst, resulting in the formation of three-component addition products [18]. To the best of our knowledge, this is the first example of the three-component addition reactions of enones with alkenes, which afford terminal alkenes [11; 19; 20].…”

Nickel‐Catalyzed Allylic Substitution of Simple Alkenes

“…In a pioneering paper in 2004, Ogoshi and coworkers reported intramolecular, Ni-mediated cyclization of alkenals in the presence of organophosphine and trimethylsilyl triflates (Me 3 SiOTf), [7a] and shortly thereafter we reported Ni-catalyzed intermolecular three-component couplings of alkenes, aldehydes, and silyl triflates. [8a] Over the past several years, both of our groups have actively investigated other related transformations.…”

“…[8a] Over the past several years, both of our groups have actively investigated other related transformations. [7-9] In our ongoing efforts in this area, we have developed highly regioselective nickel-catalyzed three-component couplings of alkenes, aldehydes, and silyl triflates, enabling the access to both homoallylic alcohols [8b] and allylic alcohols [8c] by judicious choice of reaction conditions (equation 1). Nickel-catalyzed intermolecular coupling reactions of simple terminal alkenes with α,β-unsaturated carbonyl compounds has also been reported (equation 2).…”