Publications by authors named "Colleen Munro-Leighton"

A discontinuity exists between the importance of the cation-olefin reaction as the principal C-C bond forming reaction in terpene biosynthesis and the synthetic tools for mimicking this reaction under catalyst control; that is, having the product identity, stereochemistry, and functionality under the control of a catalyst. The main reason for this deficiency is that the cation-olefin reaction starts with a reactive intermediate (a carbocation) that reacts exothermically with an alkene to reform the reactive intermediate; not to mention that reactive intermediates can also react in nonproductive fashions. In this Account, we detail our efforts to realize catalyst control over this most fundamental of reactions and thereby access steroid like compounds.

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The Pt(II) amido and phenoxide complexes ((t)bpy)Pt(Me)(X), ((t)bpy)Pt(X)(2), and [((t)bpy)Pt(X)(py)][BAr'(4)] (X = NHPh, OPh; py = pyridine) have been synthesized and characterized. To test the feasibility of accessing Pt(IV) complexes by oxidizing their Pt(II) precursors, the previously reported ((t)bpy)Pt(R)(2) (R = Me and Ph) systems were oxidized with I(2) to yield ((t)bpy)Pt(R)(2)(I)(2). The analogous reaction with ((t)bpy)Pt(Me)(NHPh) and MeI yields the corresponding ((t)bpy)Pt(Me)(2)(NHPh)(I) complex.

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Synthesis and characterization of the monomeric complex ((t)bpy)Pt(Me)(NHPh) ((t)bpy = 4,4'-di-tert-butyl-2,2'-dipyridyl) has been accomplished. Mechanistic studies reveal that 1,2-addition of dihydrogen across the Pt-anilido bond to initially produce ((t)bpy)Pt(Me)(H) and free aniline is catalyzed by elemental Pt rather than through a pathway that involves direct activation of H(2) by Pt and 1,2-addition across the Pt-NHPh bond.

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Synthesis and isolation of the monomeric octahedral platinum(IV) amido complex (NCN)PtMe2NHPh have been accomplished upon deprotonation of the amine complex [(NCN)PtMe2(NH2Ph)][OTf]. The preliminary reactivity of the amido ligand has been explored.

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Monomeric Cu(I) amido and thiolate complexes that are supported by the N-heterocyclic carbene ligand 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) catalyze the hydroamination and hydrothiolation of electron-deficient vinylarenes with reactivity patterns that are consistent with an intermolecular nucleophilic addition of the amido/thiolate ligand of (IPr)Cu(XR) (X = NH or S; R = Ph, CH2Ph) to free vinylarene.

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A series of monomeric (NHC)Cu(SR) (R = Ph or CH2Ph; NHC = N-heterocyclic carbene) complexes have been synthesized and fully characterized including single-crystal X-ray diffraction studies. These complexes catalyze the addition of S-H bonds across electron-deficient olefins to regioselectively produce "anti-Markovnikov" products.

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The monomeric Cu(I) complexes (IPr)Cu(Z) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, Z = NHPh, OEt, or OPh) react with YH (Y = PhNH, PhCH2NH, EtO, or PhO) to catalytically add Y-H bonds across the C=C bond of electron-deficient olefins to yield anti-Markovnikov organic products. Catalytic activity has been observed for olefins CH2C(H)(X) with X = CN, C(O)Me, or CO2Me as well as crotononitrile. Preliminary studies implicate an intermediate in which the C-Y bond forms through a nucleophilic addition pathway.

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The monomeric copper(I) alkyl complexes (IPr)Cu(R) [R = Me or Et; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] react with substrates that possess N-H, O-H, and acidic C-H bonds to form monomeric systems of the type (IPr)Cu(X) (X = anilido, phenoxide, ethoxide, phenylacetylide, or N-pyrrolyl) and methane or ethane. Solid-state X-ray crystal structures of the anilido, ethoxide, and phenoxide complexes confirm that they are monomeric systems. Experimental studies on the reaction of (IPr)Cu(Me) and aniline to produce (IPr)Cu(NHPh) suggest that a likely reaction pathway is coordination of aniline to Cu(I) followed by proton transfer to produce methane and the copper(I) anilido complex.

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