@article {2694, title = {Construction of Carbo- and Heterocycles Using Radical Relay Cyclizations Initiated by Alkoxy Radicals}, journal = {Organic Letters}, volume = {11}, number = {9}, year = {2009}, note = {ISI Document Delivery No.: 438ATTimes Cited: 5Cited Reference Count: 55Zhu, Hai Wickenden, Jason G. Campbell, Natalie E. Leung, Joe C. T. Johnson, Kayll M. Sammis, Glenn M.}, month = {May}, pages = {2019-2022}, type = {Article}, abstract = {An efficient method for the rapid construction of carbo- and heterocycles has been developed using radical relay cyclizations initiated by alkoxy radicals. Linear substrates were cyclized to form a wide range of cyclopentane, pyrrolidine, tetrahydropyran, and tetrahydrofuran derivatives in excellent yields. This methodology was utilized as a key step in the synthesis of the tetrahydrofuran fragment in (-)-amphidinolide K.}, keywords = {1, 5-HYDROGEN ATOM TRANSFER, AMPHIDINOLIDE K, C-H ACTIVATION, CARBONYLATION, CHAIN REACTIONS, EFFICIENT, FUNCTIONALIZATION, ORGANIC-SYNTHESIS, REARRANGEMENT, TRANSLOCATION REACTIONS}, isbn = {1523-7060}, url = {://000265529000039}, author = {Zhu, H. and Wickenden, J. G. and Campbell, N. E. and Leung, J. C. T. and Johnson, K. M. and Sammis, G. M.} } @article {2694, title = {Construction of Carbo- and Heterocycles Using Radical Relay Cyclizations Initiated by Alkoxy Radicals}, journal = {Organic Letters}, volume = {11}, number = {9}, year = {2009}, note = {ISI Document Delivery No.: 438ATTimes Cited: 5Cited Reference Count: 55Zhu, Hai Wickenden, Jason G. Campbell, Natalie E. Leung, Joe C. T. Johnson, Kayll M. Sammis, Glenn M.}, month = {May}, pages = {2019-2022}, type = {Article}, abstract = {An efficient method for the rapid construction of carbo- and heterocycles has been developed using radical relay cyclizations initiated by alkoxy radicals. Linear substrates were cyclized to form a wide range of cyclopentane, pyrrolidine, tetrahydropyran, and tetrahydrofuran derivatives in excellent yields. This methodology was utilized as a key step in the synthesis of the tetrahydrofuran fragment in (-)-amphidinolide K.}, keywords = {1, 5-HYDROGEN ATOM TRANSFER, AMPHIDINOLIDE K, C-H ACTIVATION, CARBONYLATION, CHAIN REACTIONS, EFFICIENT, FUNCTIONALIZATION, ORGANIC-SYNTHESIS, REARRANGEMENT, TRANSLOCATION REACTIONS}, isbn = {1523-7060}, url = {://000265529000039}, author = {Zhu, H. and Wickenden, J. G. and Campbell, N. E. and Leung, J. C. T. and Johnson, K. M. and Sammis, G. M.} } @article {1392, title = {Glucosamine conjugates of tricarbonylcyclopentadienyl rhenium(I) and technetium(I) cores}, journal = {Inorganic Chemistry}, volume = {45}, number = {17}, year = {2006}, note = {ISI Document Delivery No.: 073DPTimes Cited: 13Cited Reference Count: 43Ferreira, Cara L. Ewart, Charles B. Bayly, Simon R. Patrick, Brian O. Steele, Jennifer Adam, Michael J. Orvig, Chris}, month = {Aug}, pages = {6979-6987}, type = {Article}, abstract = {To obtain a Tc-99m glucose conjugate for imaging, double-ligand transfer (DLT) and related reactions were examined for the preparation of CpM(CO)(3) (Cp = cyclopentadienyl; M = Re, Tc) complexes with pendant carbohydrates at Cp. Tricarbonyl {N-(1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-beta-D-glucopyranose) cyclopentadienyl carboxamide} rhenium(I) (1a) and tricarbonyl {N-(2-amino-2-deoxy-beta-D-glucopyranose) cyclopentadienyl carboxamide} rhenium(I) (2a) were prepared. The compounds were fully characterized by mass spectrometry, elemental analysis, IR, and NMR spectroscopy. Full assignment of the NMR spectra verified the pendant nature of the glucosamine moieties in the solution state and that 2a exists as both anomers. The solid-state structure of 2a was determined by X-ray crystallography, again confirming the pendant nature of the glucosamine, but differing from the solution state in that the, anomer crystallized preferentially (93\%). Compound 2a was determined to be a high-affinity competitive inhibitor (K-i = 330 +/- 70 mu M) of the glucose metabolism enzyme hexokinase, demonstrating that it retains certain biological activity. The Tc-99m analogues 1b and 2b were prepared in moderate radiochemical yields by means of the single-ligand transfer (SLT) route, which is more pertinent to radiopharmaceutical synthesis.}, keywords = {BIOMOLECULES, COORDINATION, CYCLOPENTADIENYL-TRICARBONYL COMPLEXES, DERIVATIVES, FUNCTIONALIZATION, IN-VITRO, METAL-COMPLEXES, RE-186(I), RECEPTOR, TC-99M}, isbn = {0020-1669}, url = {://000239723300060}, author = {Ferreira, C. L. and Ewart, C. B. and Bayly, S. R. and Patrick, B. O. and Steele, J. and Adam,Michael J. and Orvig, Chris} } @article {1392, title = {Glucosamine conjugates of tricarbonylcyclopentadienyl rhenium(I) and technetium(I) cores}, journal = {Inorganic Chemistry}, volume = {45}, number = {17}, year = {2006}, note = {ISI Document Delivery No.: 073DPTimes Cited: 13Cited Reference Count: 43Ferreira, Cara L. Ewart, Charles B. Bayly, Simon R. Patrick, Brian O. Steele, Jennifer Adam, Michael J. Orvig, Chris}, month = {Aug}, pages = {6979-6987}, type = {Article}, abstract = {To obtain a Tc-99m glucose conjugate for imaging, double-ligand transfer (DLT) and related reactions were examined for the preparation of CpM(CO)(3) (Cp = cyclopentadienyl; M = Re, Tc) complexes with pendant carbohydrates at Cp. Tricarbonyl {N-(1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-beta-D-glucopyranose) cyclopentadienyl carboxamide} rhenium(I) (1a) and tricarbonyl {N-(2-amino-2-deoxy-beta-D-glucopyranose) cyclopentadienyl carboxamide} rhenium(I) (2a) were prepared. The compounds were fully characterized by mass spectrometry, elemental analysis, IR, and NMR spectroscopy. Full assignment of the NMR spectra verified the pendant nature of the glucosamine moieties in the solution state and that 2a exists as both anomers. The solid-state structure of 2a was determined by X-ray crystallography, again confirming the pendant nature of the glucosamine, but differing from the solution state in that the, anomer crystallized preferentially (93\%). Compound 2a was determined to be a high-affinity competitive inhibitor (K-i = 330 +/- 70 mu M) of the glucose metabolism enzyme hexokinase, demonstrating that it retains certain biological activity. The Tc-99m analogues 1b and 2b were prepared in moderate radiochemical yields by means of the single-ligand transfer (SLT) route, which is more pertinent to radiopharmaceutical synthesis.}, keywords = {BIOMOLECULES, COORDINATION, CYCLOPENTADIENYL-TRICARBONYL COMPLEXES, DERIVATIVES, FUNCTIONALIZATION, IN-VITRO, METAL-COMPLEXES, RE-186(I), RECEPTOR, TC-99M}, isbn = {0020-1669}, url = {://000239723300060}, author = {Ferreira, C. L. and Ewart, C. B. and Bayly, S. R. and Patrick, B. O. and Steele, J. and Adam,Michael J. and Orvig, Chris} } @article {1253, title = {Activation and cleavage of alkynes by the dinuclear tantalum complexes ([NPN]Ta)(2)(mu-H)(4) and ([NPN]Ta)(2)(mu-eta(1):eta(2)-N-2)(mu-H)(2) (where NPN = PhP(CH2SiMe2NPh)(2))}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {83}, number = {6-7}, year = {2005}, note = {ISI Document Delivery No.: 963UVTimes Cited: 4Cited Reference Count: 29}, month = {Jun}, pages = {652-660}, type = {Article}, abstract = {Reaction of phenylacetylene with the dinuclear tetrahydride complex ([NPN]Ta)(2)(mu-H)(4) gives the product ([NPN]Ta)(2)(mu-PhCCH)(mu-H)(2) (where NPN is PhP(CH2SiMe2NPh)(2)). Activation of other terminal alkynes by ([NPN]Ta)(2)(mu-H)(4) accesses ([NPN]Ta)(2)(mu-RCCH)(mu-H)(2) (R = n-Pr, t-Bu). Crystallographic analysis of the R = Ph derivative showed it to be a bis(mu-alkylidene) bound asymmetrically to the two tantalum centres. Storage of solutions of ([NPN]Ta)(2)(mu-PhCCH)(mu-H)(2) under vacuum promotes the loss of H-2 and cleavage of the C-C bond to give a bis(mu-alkylidyne) complex, ([NPN]Ta)(2)(mu-CPh)(mu-CH). Addition of diphenylacetylene did not give the desired ([NPN]Ta)(2)(mu-CPh)(2), but rather promotes a complex decomposition of the supporting [NPN] ligands. Reaction of phenylacetylene with the dinitrogen complex ([NPN]Ta)(2)(mu-eta(1):eta(2)-N-2)(mu-H)(2) results in the dissociation of the bound dinitrogen and the formation of ([NPN]Ta)(2)(mu-PhCCH)(mu-H)(2), which is identical to that derived from the reaction with the dinuclear tetrahydride.}, keywords = {activation of small molecules, alkylidene, alkylidyne, ALKYLIDYNE COMPLEXES, ALKYNE, amidodiphosphine, BONDS, DIAMIDOPHOSPHINE COMPLEXES, DINITROGEN CLEAVAGE, DINUCLEAR, END-ON, FUNCTIONALIZATION, hydride dinitrogen, LIGAND, N-2, NIOBIUM(III), SIDE-ON, tantalum}, isbn = {0008-4042}, url = {://000231832500020}, author = {Shaver, M. P. and Johnson, S. A. and Fryzuk,Michael D.} } @article {1252, title = {Cleavage of hydrazine and 1,1-dimethylhydrazine by dinuclear tantalum hydrides: Formation of imides, nitrides, and N,N-dimethylamine}, journal = {Journal of the American Chemical Society}, volume = {127}, number = {2}, year = {2005}, note = {ISI Document Delivery No.: 887RZTimes Cited: 11Cited Reference Count: 21}, month = {Jan}, pages = {500-501}, type = {Article}, keywords = {BRIDGING N-2 UNIT, COORDINATION, DINITROGEN COMPLEX, END-ON, FUNCTIONALIZATION, LIGAND, METAL-COMPLEXES, N-N BOND, REDUCTIVE CLEAVAGE, SIDE-ON}, isbn = {0002-7863}, url = {://000226324500013}, author = {Shaver, M. P. and Fryzuk,Michael D.} } @article {1186, title = {Hydroalumination of a dinuclear tantalum dinitrogen complex: N-N bond cleavage and ancillary ligand rearrangement}, journal = {Organometallics}, volume = {24}, number = {16}, year = {2005}, note = {ISI Document Delivery No.: 949ZKTimes Cited: 15Cited Reference Count: 32}, month = {Aug}, pages = {3836-3841}, type = {Article}, abstract = {The addition of diisobutylaluminum hydride (DIBAL) to the side-on end-on dinitrogen complex ([NPN]Ta)(2)(mu-eta(1):eta(2)-N-2)(mu-H)(2), 1 (where [NPN] = (PhNSiMe2CH2)(2)PPh), is described. The two end products are diastereomeric rotational isomers in which N-N bond cleavage has occurred with an Al(Bu-i)H group attached to one of the nitride atoms. The reaction proceeds through addition of DIBAL to 1 to generate a thermally sensitive intermediate that has been characterized in solution as the result of Al-H addition across the TaN2 moiety, namely, ([NPN]TaH)(mu-eta(1):eta(2)-NNA1(i)Bu(2))(mu-H)(2)(Ta[NPN), 2. This material subsequently rearranges via a second thermally labile intermediate to ultimately generate two diastereomeric end products that show N-N bond cleavage, loss of H-2, loss of an aluminum isobutyl group, and NPN ligand migration from tantalum to aluminum. Both of these complexes have been isolated in crystalline form and analyzed by single-crystal X-ray diffraction. The second thermally sensitive intermediate has been characterized on the basis of multinuclear NMR spectroscopy as ([NPN]TaH)(mu-eta(1):eta(2)-(NNAlBu)-Bu-i(mu-H))(mu-H)(2)(Ta[NPN), 3.}, keywords = {ACTIVATION, ATMOSPHERIC NITROGEN, CHEMISTRY, COORDINATED DINITROGEN, END-ON, FUNCTIONALIZATION, METAL-COMPLEXES, MOLECULAR NITROGEN, N-2, SIDE-ON}, isbn = {0276-7333}, url = {://000230827200007}, author = {MacKay, B. A. and Patrick, B. O. and Fryzuk,Michael D.} } @article {947, title = {Carbon-nitrogen bond formation via the reaction of terminal alkynes with a dinuclear side-on dinitrogen complex}, journal = {Journal of the American Chemical Society}, volume = {126}, number = {31}, year = {2004}, note = {ISI Document Delivery No.: 843TSTimes Cited: 27Cited Reference Count: 21}, month = {Aug}, pages = {9480-9481}, type = {Article}, keywords = {ACTIVATION, COORDINATION, FIXATION, FUNCTIONALIZATION, HETEROCYCLES, HYDROAMINATION, METAL-COMPLEXES, MOLECULAR NITROGEN, MOLYBDENUM, N-2}, isbn = {0002-7863}, url = {://000223110100007}, author = {Morello, L. and Love, J. B. and Patrick, B. O. and Fryzuk,Michael D.} } @article {994, title = {Spectroscopic properties and quantum chemistry-based normal coordinate analysis (QCB-NCA) of a dinuclear tantalum complex exhibiting the novel side-on end-on bridging geometry of N-2: Correlations to electronic structure and reactivity}, journal = {Journal of the American Chemical Society}, volume = {126}, number = {1}, year = {2004}, note = {ISI Document Delivery No.: 761ZMTimes Cited: 16Cited Reference Count: 40}, month = {Jan}, pages = {280-290}, type = {Article}, abstract = {The vibrational properties and the electronic structure of the side-on end-on N-2-bridged Ta complex ([NPN]Ta(mu-H))(2)(mu-eta(1):eta(2)-N-2) (1) (where [NPN] = (PhNSiMe2CH2)(2)PPh) are analyzed. Vibrational characterization of the Ta-2(mu-N-2)(mu-H)(2) core is based on resonance Raman and infrared spectroscopies evaluated with a novel quantum chemistry-based normal coordinate analysis (QCB-NCA). The N-N stretching frequency is found at 1165 cm(-1) exhibiting a N-15(2) isotope shift of -37 cm(-1). Four other modes of the Ta2N2H2 core are observed between 430 and 660 cm(-1). Two vibrations of the bridging hydrido ligands are also identified in the spectra. On the basis of experimental frequencies and the QCB-NCA procedure, the N-N force constant is determined to be 2.430 mdyn -Angstrom(-1). The Ta-N force constants are calculated to be 2.517 mdyn Angstrom(-1) for the Ta-eta(1)-N-2 bond and 1.291 and 0.917 mdyn Angstrom(-1) for the Ta-eta(2)-N-2 bonds, respectively. DFT calculations on 1 suggest that the bridging dinitrogen ligand carries a charge of -1.1, which is equally distributed over the two nitrogen atoms. However, orbital analysis reveals that the terminal nitrogen makes lower contributions to the pi orbitals and much higher contributions to the pi* orbitals of the N-2 ligand than the bridging nitrogen. This suggests that reactions of the dinitrogen ligand with electrophiles should preferentially occur at the terminal N atom, in agreement with experimental results.}, keywords = {ACTIVATION, CLEAVAGE, DINITROGEN FIXATION, EFFECTIVE CORE POTENTIALS, FUNCTIONALIZATION, LIGAND, MOLECULAR CALCULATIONS, MOLYBDENUM, NITROGEN-FIXATION, REDUCTION PATHWAY}, isbn = {0002-7863}, url = {://000187945400064}, author = {Studt, F. and MacKay, B. A. and Fryzuk,Michael D. and Tuczek, F.} } @article {734, title = {Vanadium and niobium diamidophosphine complexes and their reactivity}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {81}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 751CNTimes Cited: 7Cited Reference Count: 27}, month = {Dec}, pages = {1431-1437}, type = {Article}, abstract = {The tridentate ligand precursors R{\textquoteright}P(CH2SiMe2NR")(2) ((R{\textquoteright}R{\textquoteright}{\textquoteright})[NPN]: R{\textquoteright} = Cy, Ph; R" = Ph, Mes, Me) were prepared from metathesis reactions of a lithiated amine, chloro(chloromethyl)dimethylsilane, the appropriate 1degrees phosphine, and n-butyl lithium and were isolated as solvent adducts. Metathesis between (CyPh)[NPN]Li-2(OEt2), 2, and VCl3(THF)(3) afforded ((CyPh)[NPN]VCl)(2), 7, whose solid-state structure was established by X-ray crystallography. Reduction attempts of the ((R{\textquoteright}R{\textquoteright}{\textquoteright})[NPN]VCl)(2) species with KC8 incorporated molecular nitrogen but were complicated by imide formation and ligand decomposition. Metathesis of 2 with NbCl2Me3 afforded the highly unstable complex (CyPh)[NPN]NbMe3, 15. Attempts to hydrogenate this species were unsuccessful.}, keywords = {3-COORDINATE MOLYBDENUM(III), BRIDGING N-2 UNIT, COORDINATION, COORDINATION CHEMISTRY, DINITROGEN COMPLEX, END-ON, FUNCTIONALIZATION, HYDROGENATION, LIGAND, METATHESIS, NIOBIUM, REDUCTION, REDUCTIVE CLEAVAGE, SIDE-ON, TANTALUM COMPLEX, VANADIUM}, isbn = {0008-4042}, url = {://000187035400001}, author = {Shaver, M. P. and Thomson, R. K. and Patrick, B. O. and Fryzuk,Michael D.} } @article {328, title = {C-H activation of substituted arenes by tungsten alkylidene complexes: Products, selectivity, and mechanism}, journal = {Organometallics}, volume = {21}, number = {7}, year = {2002}, note = {ISI Document Delivery No.: 534QZTimes Cited: 18Cited Reference Count: 35}, month = {Apr}, pages = {1474-1486}, type = {Article}, abstract = {Thermolyses (70 degreesC, 40 h) of Cp*W(NO)(CH2CMe3)(2) (1) and Cp*W(NO)(CH2CMe3)(CH2C6H5) (2) in xylenes, mesitylene, and a,a,(x-trifluorotoluene generate mixtures of the corresponding aryl and/or benzyl products derived from aromatic sp(2) and benzylic sp(3) C-H bond activations of the solvent molecules by the intermediate alkylidene complexes Cp*W(NO)(=CHCMe3)(sigma-CMe4) (sigma-A) and Cp*W(NO)(=CHC6H5)(sigma-CMe4) (sigma-B), respectively. For instance, the thermolysis of 1 in p-xylene affords products resulting from the activation of one and two molecules of p-xylene. The two products derived from the activation of one solvent molecule are Cp*W(NO)(CH2CMe3)(C6H3-2,5-Me-2) (10) and CP*W(NO)(CH2CMe3)(CH2C6H4-4-Me)(2) (11). The other two complexes derived from the activation of two solvent molecules are Cp*W(NO)(CH2C6H4-4-Me)(C6H4-2,5-Me-2) (12) and Cp*W(NO)(CH2C6H4-4Me)(2) (13). The ratio of the four products in the final reaction mixture is 10:11:12:13 = 1.81 +/- 0.09:0.44 +/- 0.05:1.0:0.15 +/- 0.02. All new complexes prepared have been characterized as fully as possible by conventional spectroscopic methods, and the solid-state molecular structures of Cp*W(NO)(CH2C6H5)(C6H3-3,5-Me-2) (7) and Cp*W(NO)(CH2C6H5)(CH2C6H3-3,5-Me-2) (9) have been established by X-ray diffraction methods. Analyses of the product distributions resulting from the various thermolyses indicate that the benzyl products are increasingly favored over the aryl products as the number of methyl substituents on the solvent molecule increases. Likewise, the movement of the methyl groups from the ortho to meta to para position in the xylenes shifts the aryl vs benzyl product distribution toward the benzyl products. With respect to the aryl product regioselectivities, only the least sterically congested aryl regioisomers are formed in the activations of o- and m-xylene, while the meta and para aryl products are formed preferentially for (x,(x,(x-trifluorotoluene. Finally, the distributions obtained from sigma-B are more abundant in the aryl products than are those obtained from a-A. However, despite these general trends, it is also apparent that the origin of the observed product selectivities is highly dependent on the nature of the substrate, the nature of the C-H activation products, and the intermediate alkylidene complex.}, keywords = {1, 2-RH-ELIMINATION, ARYL, BOND ACTIVATION, CARBON-HYDROGEN, FUNCTIONALIZATION, HYDROCARBON ACTIVATION, METHANE, MOLYBDENUM, ORGANOMETALLIC NITROSYL CHEMISTRY, REVERSIBLE, THERMOLYSIS}, isbn = {0276-7333}, url = {://000174599400020}, author = {Adams, C. S. and Legzdins,Peter and Tran, E.} }