Synthesis of Pt(II)-η3-benzyl complexes: crystal structure of [Pt(Bu2tP(CH2)3PBu2t)(η3-anti-1-MeCHC6H4Br-4)][BF4]

Crascall, Louise E.; Litster, Stephen A.; Redhouse, A. D.; Spencer, John L.

doi:10.1016/0022-328x(90)87277-k

Cited by 36 publications

(12 citation statements)

References 6 publications

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“…It is not possible at this stage to know if the protonation sites are the kinetic sites or the thermodynamic sites; we assume for now that they are the kinetic sites. 1-Phenyl complexes are virtually unknown in the literature; a cationic 1-phenethyl complex of Pt(II) was found to have an η 3 -benzallylic structure …”

Section: Resultsmentioning

confidence: 99%

Interconversion of Molybdenum or Tungsten d² Styrene Complexes with d⁰ 1-Phenethylidene Analogues

et al. 2021

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Upon addition of 5−15% PhNMe 2 H + X − (X = B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 or B(C 6 F 5 ) 4 ) to Mo(NAr)(styrene)(OSiPh 3 ) 2 (Ar = N-2,6-i-Pr 2 C 6 H 3 ) in C 6 D 6 an equilibrium mixture of Mo(NAr)-(styrene)(OSiPh 3 ) 2 and Mo(NAr)(CMePh)(OSiPh 3 ) 2 is formed over 36 h at 45 °C (K eq = 0.36). A plausible intermediate in the interconversion of the styrene and 1-phenethylidene complexes is the 1-phenethyl cation, [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 ] + , which can be generated using [(Et 2 O) 2 H][B(C 6 F 5 ) 4 ] as the acid. The interconversion can be modeled as two equilibria involving protonation of Mo(NAr)(styrene)(OSiPh 3 ) 2 or Mo(NAr)(CMePh)(OSiPh 3 ) 2 and deprotonation of the α or β phenethyl carbon atom in [Mo(NAr)-(CHMePh)(OSiPh 3 ) 2 ] + . The ratio of the rate of deprotonation of [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 ] + by PhNMe 2 in the α position versus the β position is ∼10, or ∼30 per H β . The slow step is protonation of Mo(NAr)(styrene)(OSiPh 3 ) 2 (k 1 = 0.158(4) L/(mol• min)). Proton sources such as (CF 3 ) 3 COH or Ph 3 SiOH do not catalyze the interconversion of Mo(NAr)(styrene)(OSiPh 3 ) 2 and Mo(NAr)(CMePh)(OSiPh 3 ) 2 , while the reaction of Mo(NAr)(styrene)(OSiPh 3 ) 2 with pyridinium salts generates only a trace (∼2%) of Mo(NAr)(CMePh)(OSiPh 3 ) 2 and forms a monopyridine adduct, [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 (py)] + (two diastereomers). The structure of [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 ] + has been confirmed in an X-ray study; there is no structural indication that a β proton is activated through a CH β interaction with the metal. W(NAr)(CMePh)(OSiPh 3 ) 2 is also converted into a mixture of W(NAr)(CMePh)(OSiPh 3 ) 2 and W(NAr)(styrene)(OSiPh 3 ) 2 (K eq = 0.47 at 45 °C in favor of the styrene complex) with 10% [PhNMe 2 H][B(C 6 F 5 ) 4 ] as the catalyst; the time required to reach equilibrium is approximately the same as in the Mo system.

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Section: Resultsmentioning

confidence: 99%

Interconversion of Molybdenum or Tungsten d² Styrene Complexes with d⁰ 1-Phenethylidene Analogues

et al. 2021

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“…However, use of alcoholic solvent enabled benzylic acetates to react with various nucleophiles. 48 The reaction of benzyl acetate (26) with active methine 27 proceeded in high yield when tertamyl alcohol was employed as the solvent (Scheme 18). Ethanol was an effective solvent for the palladium-catalyzed benzylic amination (Scheme 19) and sulfonylation (Scheme 20) of 26.…”

Section: Scheme 17 Nucleophilic Substitution Of Diphenylmethyl Carbonatementioning

confidence: 99%

Catalytic Transformations of Benzylic Carboxylates and Carbonates

Kuwano¹

2009

Synthesis

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Benzylic carboxylates and carbonates react with various molecules in the presence of homogeneous palladium or cobalt catalysts. The catalytic transformations occur at the benzylic carbons of the substrates, affording benzylic substitution products. This review surveys the catalytic reactions using benzylic carboxylates and carbonates as substrates. Furthermore, the related studies on (h 3benzyl)metal complexes are summarized in order to facilitate the understanding and consideration of the catalytic substitution. 1 Introduction 2 Chemistry of the (h 3-Benzyl)metal Complex 2.1 Structure of the (h 3-Benzyl)metal Complex 2.2 Reactivity of the (h 3-Benzyl)metal Complex 3 Catalytic Transformations of Benzylic Esters 3.

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“…This unique regioselectivity has been attributed to the stabilizing effect of a p-benzyl interaction available only to the branched isomer 3. [2] p-Benzyl complexes of a variety of transition metals [10][11][12][13][14][15] including rhodium [16][17][18][19][20][21] have been isolated, however, there is no empirical evidence to definitively ascribe the regioselectivity in the rhodiumcatalyzed hydroboration to this interaction.…”

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confidence: 99%

Regioselectivity of the Rhodium‐Catalyzed Hydroboration of Vinyl Arenes: Electronic Twists and Mechanistic Shifts

et al. 2007

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Any substituent does it: The hydroboration of vinyl arenes with pinacol borane (HBPin) and cationic rhodium complexes selectively placed the boron proximal to the aryl rather than phenyl ring, regardless of whether this ring bears electron‐donating or electron‐withdrawing substituents. In competition experiments between styrene and various vinyl arenes, preferential hydroboration also occured at the substituted arene (see scheme). Hammett plots indicate a break in the mechanism.

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Synthesis of Pt(II)-η3-benzyl complexes: crystal structure of [Pt(Bu2tP(CH2)3PBu2t)(η3-anti-1-MeCHC6H4Br-4)][BF4]

Cited by 36 publications

References 6 publications

Interconversion of Molybdenum or Tungsten d² Styrene Complexes with d⁰ 1-Phenethylidene Analogues

Interconversion of Molybdenum or Tungsten d² Styrene Complexes with d⁰ 1-Phenethylidene Analogues

Catalytic Transformations of Benzylic Carboxylates and Carbonates

Regioselectivity of the Rhodium‐Catalyzed Hydroboration of Vinyl Arenes: Electronic Twists and Mechanistic Shifts

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Synthesis of Pt(II)-η3-benzyl complexes: crystal structure of [Pt(Bu2tP(CH2)3PBu2t)(η3-anti-1-MeCHC6H4Br-4)][BF4]

Cited by 36 publications

References 6 publications

Interconversion of Molybdenum or Tungsten d2 Styrene Complexes with d0 1-Phenethylidene Analogues

Interconversion of Molybdenum or Tungsten d2 Styrene Complexes with d0 1-Phenethylidene Analogues

Catalytic Transformations of Benzylic Carboxylates and Carbonates

Regioselectivity of the Rhodium‐Catalyzed Hydroboration of Vinyl Arenes: Electronic Twists and Mechanistic Shifts

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Product

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Interconversion of Molybdenum or Tungsten d² Styrene Complexes with d⁰ 1-Phenethylidene Analogues

Interconversion of Molybdenum or Tungsten d² Styrene Complexes with d⁰ 1-Phenethylidene Analogues