An experimental–theoretical approach to the kinetics and mechanism of Michael type addition: α,β-Unsaturated tungsten Fischer carbene complex as the substrate

Gu, Kaichun; Yang, Gang; Zhang, Weiping; Liu, Xiumei; Yu, Zhengkun; Han, Xiuwen; Bao, Xinhe

doi:10.1016/j.jorganchem.2005.12.063

Cited by 8 publications

(2 citation statements)

References 48 publications

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“…Frontier orbitals of these cycloaddends were obtained from B3LYP/6-31G* calculations . The structures of carbenes 1a , d were fully optimized at the same level of theory, showing that the ethoxy group can adopt two distinct conformations, in accordance with other reports . Thus, we carried out the corresponding geometry optimizations and frequency analysis on the anti and syn geometries.…”

Section: Resultssupporting

confidence: 62%

Synthesis of New Polycyclic Oxazol-2-one Derivatives by a Tandem [4 + 2] Cycloaddition/Cyclopentannulation/1,5-Sigmatropic Rearrangement Process of Fischer (Arylalkynyl)(alkoxy)carbenes and exo-2-Oxazolidinone Dienes

et al. 2008

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An efficient and simple synthesis of highly substituted 9-ethoxy-3-phenyl-3H-fluorene[3,2-d]oxazol-2-(4H,9H,10H)-one derivatives 10a−f by a tandem [4 + 2] cycloaddition/cyclopentannulation process of Fischer (arylethynyl)(ethoxy)carbene complexes (CO)5MC(CCC6H4-R)OCH2CH3 (1a, M = Cr, R = H; 1b, M = Cr, R = p-CH3; 1c, M = Cr, R = p-OCH3; 1d, M = W, R = H; 1e, M = W, R = p-CH3; 1f, M = W, R = p-OCH3) with exo-2-oxazolidinone dienes 7a−d is described. A study of reactivity as well as regio- and stereoselectivity in a tandem process of the Fischer carbene complexes 1 with the exo-heterocyclic dienes 7 was carried out. The cycloadditions were found to be highly regioselective, favoring the para cycloadducts, and highly stereoselective, giving the trans diastereoisomers. The stereochemical assignment of the cycloadducts was supported by NOE measurements, and the derivatives 10b,c,e were further characterized by single crystal X-ray diffraction. A rationalization of the regioselectivity was carried out through an FMO analysis of the energies and coefficients for the most stable conformations of carbenes 1a,d and for diene 7a, showing a stronger interaction for the observed para cycloadduct than for the meta regioisomer. The aromatization of cycloadducts 10a−f with HCl and DDQ is also reported.

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Section: Resultssupporting

confidence: 62%

Synthesis of New Polycyclic Oxazol-2-one Derivatives by a Tandem [4 + 2] Cycloaddition/Cyclopentannulation/1,5-Sigmatropic Rearrangement Process of Fischer (Arylalkynyl)(alkoxy)carbenes and exo-2-Oxazolidinone Dienes

et al. 2008

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“…The highly precise double numerical with polarization (DNP) basis set was adopted through the present research, which proves even more reliable than the commonly used 6-31G(d, p) basis. To describe the structures of transition states and energy barriers as precisely as possible, the complete linear synchronous transit/quadratic synchronous transit (complete LST/QST) protocol in DMOL 3 module was employed for the transition-state searching . Evaluations of molecular Hessians for the transition-state structures were performed confirming that the transition-state structures were characterized by only one imaginary frequency corresponding to the normal mode associated with the reaction coordinate.…”

Section: Calculation Detailsmentioning

confidence: 99%

Density Functional Theoretical Investigations on Various Nanostructural Zeolite Surfaces

et al. 2006

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Through density functional calculations, the Brønsted acidities on various nanostructural ZSM-5 zeolite surfaces were studied as well as the hydrogen exchanging processes with adsorbed H(2)O monomer or dimer. The Brønsted acidities on the four nanostructural surfaces show differences, although slightly, with their strengths increasing as (100) < (210) < (410) < (001). For hydrogen exchanging processes with H(2)O monomer or dimer, the reaction rate increases in the order (210) < (100) < (001) < (410) or (210) < (410) < (001). No transition-state structure is present on H(2)O dimer/(100) surface system. The introduction of a second H(2)O molecule accelerates the hydrogen exchanging processes and meanwhile influences the nanostructural geometries such that they are more evident. Besides the activation barrier, the adsorption energy and reaction heat display differences from one surface to another, which results in the preference of catalytic reactions to a specific nanostructural zeolite surface, such as the hydrogen exchanging processes studied in this paper.

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Lewis Acid Catalyzed Addition of Pyrazoles to Alkynes: Selective Synthesis of Double and Single Addition Products

et al. 2008

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Silver and zinc salts were found to efficiently catalyze the addition of an N-H bond of pyrazoles to alkynes. With silver triflate as a catalyst, two pyrazoles regioselectively attacked the same carbon atom of the CϵC bond of aliphatic terminal alkynes to give gem-dipyrazolylalkanes predominantly. Replacement of silver triflate with zinc triflate allows us to achieve double addition of pyrazoles to aromatic terminal alkynes. In contrast to the selective double addition, the corresponding single addition of aliphatic and aromatic terminal

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An experimental–theoretical approach to the kinetics and mechanism of Michael type addition: α,β-Unsaturated tungsten Fischer carbene complex as the substrate

Cited by 8 publications

References 48 publications

Synthesis of New Polycyclic Oxazol-2-one Derivatives by a Tandem [4 + 2] Cycloaddition/Cyclopentannulation/1,5-Sigmatropic Rearrangement Process of Fischer (Arylalkynyl)(alkoxy)carbenes and exo-2-Oxazolidinone Dienes

Synthesis of New Polycyclic Oxazol-2-one Derivatives by a Tandem [4 + 2] Cycloaddition/Cyclopentannulation/1,5-Sigmatropic Rearrangement Process of Fischer (Arylalkynyl)(alkoxy)carbenes and exo-2-Oxazolidinone Dienes

Density Functional Theoretical Investigations on Various Nanostructural Zeolite Surfaces

Lewis Acid Catalyzed Addition of Pyrazoles to Alkynes: Selective Synthesis of Double and Single Addition Products

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