Reversible Alkene Extrusion from Platinaoxetanes

Szuromi, Endre; Wu, Jieying; Sharp, Paul R.

doi:10.1021/ja065207s

Cited by 18 publications

(21 citation statements)

References 8 publications

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“…2-Platinaoxetanes with two Lewis acids on the oxygen atom have been implicated in Lewis acid-catalyzed alkene exchange reactions (eq ) . In an attempt to obtain a stable complex with two Lewis acid centers coordinated to the oxygen atom, the bidendate Lewis acid C 6 F 4 (BC 6 F 5 ) 2 (Ar = C 6 F 5 ) was added to 2-platinaoxetane 6 (eq ).…”

Section: Resultsmentioning

confidence: 99%

“…In contrast to C 6 F 4 (BC 6 F 5 ) 2 , excess BF 3 simply converts 6 to 2-platinaoxetane 2 , which is stable in the presence of BF 3 but susceptible to alkene exchange via coordination of a second BF 3 (eq ) . Stability to excess BF 3 is lost when the COD ligand of 2 is replaced by phosphine ligands.…”

Section: Resultsmentioning

confidence: 99%

“…1-Metalla-2-oxacyclobutanes (2-metallaoxetanes) have long been thought to be important in both homogeneous and heterogeneous alkene oxidations, epoxide reactions, and other transition metal-mediated transformations. − Over the years a number of transition metal 2-metallaoxetanes have been prepared and studied, ,− but complete exploration of their chemistry and validation of their involvement in these transition metal (TM)-meditated reactions remains to be fully achieved.…”

Section: Introductionmentioning

confidence: 99%

“…Many of the reported studies of 2-metallaoxetanes are related to alkene oxidation. In some cases it has been shown that 2-metallaoxetanes can form from oxidation of alkene complexes. ,,,, Of further relevance to TM-mediated olefin oxidation (e.g., the Wacker process) is the formation of 2-metallaoxetanes by coupling of an alkene with an oxo or hydroxo complex. ,,, In some reactions the coupling can be reversible. ,, However, alkene coupling to give 2-metallaoxetanes appears to be rare for oxo and hydroxo complexes, and the factors involved are not clear.…”

Section: Introductionmentioning

confidence: 99%

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Reactivity and Stability of 2-Platinaoxetanes

Sharp

2009

Organometallics

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The influence of ancillary ligands, Lewis acids, carbon substituents, and oxidants on the stability and reactivity of 2-platinaoxetanes was investigated through the reactions of 2-platinaoxetanes Pt(L2)(AOC7H10) (L2 = COD, 2PEt3, 2PPh3, dppe, But 2bpy, Me2bpy; A = nothing or a Lewis acid; C7H10 = norbornene) with Lewis acids, alkenes, H2O2, and Br2. Addition of catalytic or stoichiometric amounts of BF3 to 2-platinaoxetanes PtL2(C7H10OBF3) (L2 = 2PEt3 (7), 2PPh3 (8), dppe (9), But 2bpy (10), Me2bpy (11)) in the presence of benzonorbornene diacetate (NB2) does not give alkene exchange, as observed previously for Pt(COD)(C7H10OBF3) (2), but only norbornene extrusion. The Pt products are hydroxo complexes [PtL2(μ-OH)]2(BF3OH)2 for L = PPh3 and PEt3 or unidentified compounds. Treatment of Pt(COD)(BF3OC7H10) (2) with ethylene in the presence of catalytic or stoichiometric amounts of BF3 affords norbornene, acetaldehyde, and allyl complex [Pt(COD)(η3-CH2CHCHCH3)]X (X = BF3OH or BF4, 12). Similar reactions of 2 or 2-platinaoxetane [Pt2(COD)2(OC7H10)Cl]BF4 (1) with isobutylene give norbornene, allyl complex [Pt(COD)(η3-CH2C(CH3)CH2)]BF4 (13), Pt(COD)Cl2 (for 1 only), and presumably water. To investigate the stability of 2-platinaoxetanes with different oxygen-coordinated Lewis acids, Pt(COD)(C7H10O) (6) was treated with 1,2-C6F4(BAr2)2 (Ar = C6F5), HBF4, MeOTf, or Ph3PAuOTf, and PtL2(C7H10O) (L2 = 2PEt3 (5), 2PPh3 (18), dppe (19)) were treated with HBF4. In each case, norbornene (NB) extrusion is observed. (Complexes 18 and 19 are reported here for the first time.) In contrast, the reaction of 6 with HCl(g) in toluene/water yields Pt(COD)(Cl)(C7H10OH) (20). NB extrusion is observed in dry C6D6. Both processes occur in CD2Cl2 or CD3OD. Complex 20 also forms in the reaction of 2-platinaoxetane 1 with HCl(aq). Treatment of 6 with Br2 gives rapid elimination of norbornene oxide with formation of Pt(COD)Br2. H2O2(aq) and 6 give Pt(COD)(OH)(C7H10OH) (21), an OH analogue of 20.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reactivity and Stability of 2-Platinaoxetanes

Sharp

2009

Organometallics

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“…several studies have been published in recent years in which clear evidence for oxametallacyclobutanes as discrete intermediates was presented. [3,[25][26][27][28][29][30][31] Likewise, azametallacyclobutanes have been regarded as possible reaction intermediates from the time they were first invoked by Hegedus and McGuire in 1982. [32] Perhaps most prominently, their involvement in the hydroamination of alkenes and alkynes has been described.…”

Section: Introductionmentioning

confidence: 99%

Formation of Substituted Oxa‐ and Azarhodacyclobutanes

Dauth

Rigling

Tsoung

et al. 2013

Chemistry A European J

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The preparation of substituted oxa- and azarhodacyclobutanes is reported. After exchange of ethylene with a variety of unsymmetrically and symmetrically substituted alkenes, the corresponding rhodium-olefin complexes were oxidized with H2O2 and PhINTs (Ts=p-toluenesulfonyl) to yield the substituted oxa- and azarhodacyclobutanes, respectively. Oxarhodacyclobutanes could be prepared with excellent selectivity for incorporation of the oxygen atom on the more substituted carbon atom of the alkene. At the same time, azarhodacyclobutanes showed good-to-excellent selectivity for heteroatom incorporation on the less substituted carbon. Furthermore, it was shown that steric modifications of the ancillary ligand have a significant influence on the selectivity of Rh-olefin complex formation as well as formation of the substituted azametallacycles.

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de‐insertion

Cornils¹

2020

Catalysis From a to Z

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Reversible Alkene Extrusion from Platinaoxetanes

Abstract: Reversible alkene extrusion from platinaoxetanes has been observed. Catalytic amounts of electrophilic Pt complexes, HOTf, Ag+, or BF3 (best) result in dramatic rate enhancements.

Cited by 18 publications

References 8 publications

Reactivity and Stability of 2-Platinaoxetanes

Reactivity and Stability of 2-Platinaoxetanes

Formation of Substituted Oxa‐ and Azarhodacyclobutanes

de‐insertion

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