Nickel/Brønsted Acid-Catalyzed Chemo- and Enantioselective Intermolecular Hydroamination of Conjugated Dienes

Abstract

A novel nickel/Brønsted acid-catalyzed asymmetric hydroamination of acyclic 1,3-dienes has been established. A wide array of primary and secondary amines can be transformed into allylic amines with high yields and high enantioselectivities under very mild conditions. Moreover, our method is compatible with various functional groups and heterocycles, allowing for late-stage functionalization of biologically active complex molecules. Remarkably, this protocol exhibits good chemoselectivity with respect to amines bearing two different nucleophilic sites. Mechanistic studies reveal that the enantioselective carbon-nitrogen bond-forming step is reversible.

Nickel/Brønsted acid dual-catalyzed regio- and enantioselective hydrophosphinylation of 1,3-dienes: access to chiral allylic phosphine oxides

“…This result further indicates that the formation of C-P bonds is irreversible, which is inconsistent with a previous report on nickel-catalyzed hydroamination reaction. 19 On the basis of our observations and previous reports, 14,19 we proposed a catalytic cycle for this nickel-catalyzed hydrophosphinaylation reaction, as depicted in Figure 4d. The Ni(0) precatalyst undergoes ligand substitution with (S)-BINAP to form chiral monomeric species I, and subsequent oxidative addition to TsOH•H 2 O (HX) forms Ni−H species II.…”

“…The use of plane chiral ligand L2, spiro ligand (R)-SDP Please do not adjust margins Please do not adjust margins to other brønsted acids, the reaction was almost inert (entries 9-13). In addition, the choice of solvent had an obvious effect on the yield, but little effect on the enantioselectivity (entries [14][15][16][17][18][19]. The reaction activity decreased obviously when the temperature was lowered (entries [20][21][22].…”

“…16 Apart from low cost and ready availability, the nickel catalyst holds a unique reactivity prole. 17 As a continuation of our previous studies on nickel-catalyzed functionalization of alkenes, 18 particularly the asymmetric hydroamination of 1,3-dienes 19 and inspired by Dong's work, 14 we speculated that the application of a smaller nickel catalyst would allow the hydrophosphinylation reaction to occur under milder conditions and has better stereocontrol, leading to the development of a highly enantioselective nickelcatalyzed reaction. Herein we describe our success in the above speculations, resulting in the development of asymmetric nickel/Brønsted acid-catalyzed hydrophosphinylation of 1,3-dienes with secondary phosphine oxides (Fig.…”

Earth-Abundant 3d Transition Metal Catalysts for Hydroalkoxylation and Hydroamination of Unactivated Alkenes

“…The methodology has a good functional group tolerance and exhibits good chemoselectivity with respect to amines bearing two different nucleophilic sites but is unsuitable to the reaction of disubstituted 1,3-dienes. The same year, a novel biphosphine ligated nickel-catalyzed asymmetric hydroamination of monosubstituted 1,3-dienes using a Brønsted acid as cocatalyst was established by the group of Yin (Figure 18, bottom) [110]. By using a catalytic combination of Ni(COD)2, enantiopure rigid ligand (S,S)-Me-DuPhos and phthalic acid as Brønsted acid, a wide series of primary and secondary amines could be selectively added to 4-aryl and 4-alkyl-substituted 1,3-dienes affording enantioenriched functionalized allylic amines in yields and with enantioselectivity up to 99%.…”

Nickel‐Catalyzed Regioselective Arylboration of Conjugated Dienes

“…On the basis of our continued interest in the nickelcatalyzed carboboration of alkenes [14] and asymmetric hydroamination of conjugated dienes, [15] we assessed the extension of these concepts to conjugated dienes, especially with regard to the regioselectivity and stereoselectivity of the reactions. In addition, we examined a new single catalyst system so as to provide an operationally simple option.…”