α‐Olefins as Alkenylmetal Equivalents in Catalytic Conjugate Addition Reactions

Ho, Chun‐Yu; Ohmiya, Hirohisa; Jamison, Timothy F.

doi:10.1002/anie.200705163

Cited by 71 publications

(40 citation statements)

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“…[2][3][4] Although more functionalized conjugate carbonyls and dienes are used as one of the partners, [5,6] the direct addition of monoenes to these systems is also an important advance in the field. [7,8] Recently, some of these alkene coupling technologies have been developed to achieve the asymmetric synthesis of biologically important molecules, with ibuprofen being a representative example.…”

mentioning

confidence: 99%

Catalytic Intermolecular Tail‐to‐Tail Hydroalkenylation of Styrenes with α Olefins: Regioselective Migratory Insertion Controlled by a Nickel/N‐Heterocyclic Carbene

2010

Angew Chem Int Ed

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confidence: 99%

Catalytic Intermolecular Tail‐to‐Tail Hydroalkenylation of Styrenes with α Olefins: Regioselective Migratory Insertion Controlled by a Nickel/N‐Heterocyclic Carbene

2010

Angew Chem Int Ed

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“…Ynoates, diaryl alkynes, mono -aryl internal alkynes, nonaromatic internal alkynes, terminal alkynes, free hydroxyl -bearing alkynes, basic secondary amine -bearing alkynes, and even alkynes with tethered aldehydes or ketones were all effi cient participants. The Z -enol silanes produced by this protocol are largely inaccessible by other synthetic methods and this process complements the powerful Trost and Jamison procedures that are E -selective [28,29] . The utility of these substrates is evident by the emergence of a range of Mukaiyama aldol reaction methodologies.…”

Section: Reductive Couplings Via Hydrogen Atom Transfer -Methods Devementioning

confidence: 99%

“…The extremely high levels of Z -isomer stereoselectivity ( > 98 : 2) can best be rationalized via the metallacycle intermediate 5 which undergoes σ -bond metathesis to afford nickel hydride 6 , followed by reductive elimination to yield the Z -selective enol silane product 7 . A mechanism consisting of a nickel π -allyl species would not be expected to lead to high selectivities of Z -enol silanes, and has been implicated in reactions leading to the selective production of E -enol silanes [28] . …”

Section: Metallacycle -Based Mechanistic Pathwaymentioning

confidence: 99%

Nickel‐Catalyzed Reductive Couplings and Cyclizations

Malik

Baxter

Montgomery

2010

Catalysis Without Precious Metals

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Many classes of standard organic transformations involve the coupling or cycloaddition of two different π -components to assemble a more functionalized product. Many such processes are amenable to the union of two complex fragments, thus allowing convergent approaches to complex organic molecules. Diels -Alder cycloadditions, Prins addition reactions, and ene reactions are examples of broadly useful processes that involve the union of two π -components in a selective manner. As a complement to these classical transformations, the reductive coupling of two π -components provides an alternative strategy for assembly of complex fragments from the same types of starting materials [1 -8] . Whereas the starting components resemble those required for the types of standard organic transformations noted above, the products obtained differ structurally and are obtained in a reduced oxidation state based on the action of the reducing agent employed.A number of transition metal catalyst/reducing agent combinations are known to promote various reductive coupling processes. In addition to the nickelcatalyzed variants that are the subject of this chapter, important advances have been made with titanium -[9 -13] , iridium - [14] , and rhodium -catalyzed variants [15] . Many reducing agents have been employed, and the most widely used classes include silanes, organozincs, organoboranes, molecular hydrogen, and alcohols. The specifi c focus of this chapter will be the development of nickel -catalyzed reductive couplings and cyclizations between a polar π -component and a non -polar π -component. This strategy allows the two π -components to be differentiated in catalytic reactions, and thus avoids homocoupling processes that are often problematic in transformations of this type. The use of either aldehydes or α , β -unsaturated carbonyls as the polar component, and alkynes as the non -polar component has been a primary focus of our laboratories and will be the subject of this chapter. Extensive related developments involving dienes as the non -polar component reported by the laboratories of Mori [16] , Sato [17] , and Tamaru [18] have been reviewed elsewhere [3] and will not be extensively discussed in this 8 Catalysis Without Precious Metals. Edited by R. Morris Bullock

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“…Recently, Jamison and co-workers successfully developed catalytic conjugate addition and allylic substitution methods in forming substituted olefins. 7 Ogoshi and co-workers reported a similar direct conjugate addition of simple alkenes to enones by using a Ni(0)/PR 3 catalyst. 8 Chelate-assisted C–H insertion methods have been successfully extended to the catalytic couplings of enones with simple alkenes.…”

Section: Introductionmentioning

confidence: 99%

Scope and Mechanistic Study of the Coupling Reaction of α,β-Unsaturated Carbonyl Compounds with Alkenes: Uncovering Electronic Effects on Alkene Insertion vs Oxidative Coupling Pathways

Kwon

Lee

2011

Organometallics

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The cationic ruthenium-hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4− (1) was found to be a highly effective catalyst for the intermolecular conjugate addition of simple alkenes to α,β-unsaturated carbonyl compounds to give (Z)-selective tetrasubstituted olefin products. The analogous coupling reaction of cinnamides with electron-deficient olefins led to the oxidative coupling of two olefinic C–H bonds in forming (E)-selective diene products. The intramolecular version of the coupling reaction efficiently produced indene and bicyclic fulvene derivatives. The empirical rate law for the coupling reaction of ethyl cinnamate with propene was determined as: rate = k[1]1[propene]0[cinnamate]−1. A negligible deuterium kinetic isotope effect (kH/kD = 1.1±0.1) was measured from both (E)-C6H5CH=C(CH3)CONHCH3 and (E)-C6H5CD=C(CH3)CONHCH3 with styrene. In contrast, a significant normal isotope effect (kH/kD = 1.7±0.1) was observed from the reaction of (E)-C6H5CH=C(CH3)CONHCH3 with styrene and styrene-d10. A pronounced carbon isotope effect was measured from the coupling reaction of (E)-C6H5CH=CHCO2Et with propene (13C(recovered)/13C(virgin) at Cβ = 1.019(6)), while a negligible carbon isotope effect (13C(recovered)/13C(virgin) at Cβ = 0.999(4)) was obtained from the reaction of (E)-C6H5CH=C(CH3)CONHCH3 with styrene. Hammett plots from the correlation of para-substituted p-X-C6H4CH=CHCO2Et (X = OCH3, CH3, H, F, Cl, CO2Me, CF3) with propene and from the treatment of (E)-C6H5CH=CHCO2Et with a series of para-substituted styrenes p-Y-C6H4CH=CH2 (Y = OCH3, CH3, H, F, Cl, CF3) gave the positive slopes for both cases (ρ = +1.1±0.1 and +1.5±0.1, respectively). Eyring analysis of the coupling reaction led to the thermodynamic parameters, Δ H‡ = 20±2 kcal mol−1 and S‡ = −42±5 e.u. Two separate mechanistic pathways for the coupling reaction have been proposed on the basis of these kinetic and spectroscopic studies.

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α‐Olefins as Alkenylmetal Equivalents in Catalytic Conjugate Addition Reactions

Cited by 71 publications

References 48 publications

Catalytic Intermolecular Tail‐to‐Tail Hydroalkenylation of Styrenes with α Olefins: Regioselective Migratory Insertion Controlled by a Nickel/N‐Heterocyclic Carbene

Catalytic Intermolecular Tail‐to‐Tail Hydroalkenylation of Styrenes with α Olefins: Regioselective Migratory Insertion Controlled by a Nickel/N‐Heterocyclic Carbene

Nickel‐Catalyzed Reductive Couplings and Cyclizations

Scope and Mechanistic Study of the Coupling Reaction of α,β-Unsaturated Carbonyl Compounds with Alkenes: Uncovering Electronic Effects on Alkene Insertion vs Oxidative Coupling Pathways

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