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Wei Wang - One of the best experts on this subject based on the ideXlab platform.
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synthesis of 2 quinolinones via a hypervalent iodine iii mediated intramolecular decarboxylative heck type reaction at room temperature
Organic Letters, 2018Co-Authors: Huaqiang Fan, Peng Pan, Yongqiang Zhang, Wei WangAbstract:A hypervalent iodine(III)-mediated intramolecular decarboxylative Heck-type reaction of 2-vinyl-phenyl oxamic acids has been developed. The unique Ring-Strain-enabled radical decarboxylation mechanism is preliminarily revealed. This protocol features metal-free reaction conditions and operational simplicity, allowing the lactamization of 2-vinylanilines using a readily accessible carbonyl source and the synthesis of various 2-quinolinones with excellent chemoselectivity at room temperature.
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Synthesis of 2‑Quinolinones via a Hypervalent Iodine(III)-Mediated Intramolecular Decarboxylative Heck-Type Reaction at Room Temperature
2018Co-Authors: Huaqiang Fan, Peng Pan, Yongqiang Zhang, Wei WangAbstract:A hypervalent iodine(III)-mediated intramolecular decarboxylative Heck-type reaction of 2-vinyl-phenyl oxamic acids has been developed. The unique Ring-Strain-enabled radical decarboxylation mechanism is preliminarily revealed. This protocol features metal-free reaction conditions and operational simplicity, allowing the lactamization of 2-vinylanilines using a readily accessible carbonyl source and the synthesis of various 2-quinolinones with excellent chemoselectivity at room temperature
George A Petersson - One of the best experts on this subject based on the ideXlab platform.
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a complete basis set model chemistry iv an improved atomic pair natural orbital method
Journal of Chemical Physics, 1994Co-Authors: John A Montgomery, Joseph W Ochterski, George A PeterssonAbstract:An improved complete basis set‐quadratic configuration interaction/atomic pair natural orbital (CBS‐QCI/APNO) model is described in this paper. It provides chemical energy differences (i.e., D0 I.P., and E.A.) with a mean absolute error of 0.53 kcal/mol for the 64 first‐row examples from the G2 test set, and is computationally feasible for species with up to three first‐row atoms. A set of 20 CBS‐QCI/APNO bond dissociation energies of hydrocarbons also agree with known experimental values to within less than 1 kcal/mol. Calculations on the cyclopropenyl radical and cyclopropenylidene provide new dissociation energies which are in accord with an interpretation of the thermochemistry emphasizing Ring Strain and aromaticity.An improved complete basis set‐quadratic configuration interaction/atomic pair natural orbital (CBS‐QCI/APNO) model is described in this paper. It provides chemical energy differences (i.e., D0 I.P., and E.A.) with a mean absolute error of 0.53 kcal/mol for the 64 first‐row examples from the G2 test set, and is computationally feasible for species with up to three first‐row atoms. A set of 20 CBS‐QCI/APNO bond dissociation energies of hydrocarbons also agree with known experimental values to within less than 1 kcal/mol. Calculations on the cyclopropenyl radical and cyclopropenylidene provide new dissociation energies which are in accord with an interpretation of the thermochemistry emphasizing Ring Strain and aromaticity.
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a complete basis set model chemistry iv an improved atomic pair natural orbital method
Journal of Chemical Physics, 1994Co-Authors: John A Montgomery, Joseph W Ochterski, George A PeterssonAbstract:An improved complete basis set‐quadratic configuration interaction/atomic pair natural orbital (CBS‐QCI/APNO) model is described in this paper. It provides chemical energy differences (i.e., D0 I.P., and E.A.) with a mean absolute error of 0.53 kcal/mol for the 64 first‐row examples from the G2 test set, and is computationally feasible for species with up to three first‐row atoms. A set of 20 CBS‐QCI/APNO bond dissociation energies of hydrocarbons also agree with known experimental values to within less than 1 kcal/mol. Calculations on the cyclopropenyl radical and cyclopropenylidene provide new dissociation energies which are in accord with an interpretation of the thermochemistry emphasizing Ring Strain and aromaticity.
Robert D Bach - One of the best experts on this subject based on the ideXlab platform.
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Ring Strain energy in the cyclooctyl system the effect of Strain energy on 3 2 cycloaddition reactions with azides
Journal of the American Chemical Society, 2009Co-Authors: Robert D BachAbstract:Ring Strain energies (SEs) and enthalpies of hydrogenation (ΔHhyd) of a series of E- and Z-alkenes, cyclic alkynes and allenes (C5−C9) are computed at the G3 level of theory. The SE for cycloheptyne, cyclohexyne, and cyclopentyne are calculated to be 25.4, 40.1, and 48.4 kcal/mol, respectively. The SE for E-cycloheptene and E-cyclohexene are calculated to be 25.2 and 49.3 kcal/mol (G3). The SE of cyclooctyne is 2.0 kcal/mol greater than that of E-cyclooctene (17.9 kcal/mol) but only 7.7 kcal/mol greater than that of cyclooctane. The SE of 3,3-difluorocyclooctyne (DIFO) is predicted to be slightly reduced (ΔSE = 2.6 kcal/mol) relative to the parent cyclooctyne to 17.3 kcal/mol. The SE and ΔHhyd are correlated with activation barriers for the [3 + 2] cycloaddition of a series of azides to E- and Z-cycloalkenes and alkynes at the G3 level of theory. The energy barrier for the cycloaddition of methyl azide to cyclooctyne is 9.2 kcal/mol lower than addition to 4-octyne and 3.1 kcal/mol lower for reaction with ...
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Strain energy of small Ring hydrocarbons influence of c h bond dissociation energies
Journal of the American Chemical Society, 2004Co-Authors: Robert D Bach, Olga DmitrenkoAbstract:Ab initio calculations at the G2, G3, and CBS-Q levels of theory have been applied to the question of the origin of Ring Strain in a series of unsaturated hydrocarbons. In addition to the angular Ring Strain germane to all three-membered Ring hydrocarbons, a general trend is in evidence that suggests that the increased Ring Strain (SE) of unsaturated small Ring alkenes may be attributed in part to their relatively weak allylic C−H bonds. The high Strain energy of cyclopropene (54.1 kcal/ mol) is attributed largely to angular Strain. The anomalously low SE of cyclobutene relative to cyclobutane (ΔSE = 4 kcal/mol) is a consequence of normal C−H bond dissociation energies for cyclobutane (100.6 kcal/mol) and very strong vinyl C−H bonds (111.9 kcal/mol) and a relatively strong π-bond energy (63.5 kcal/mol) for cyclobutene. The greater SE of methylenecyclopropane (39.5 kcal/ mol), relative to methylcyclopropane (29.8 kcal/mol), can be attributed to the strong Ring C−H bonds of methylcyclopropane (110.5 kcal/mo...
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Strain energy of small Ring hydrocarbons influence of c h bond dissociation energies
Journal of the American Chemical Society, 2004Co-Authors: Robert D Bach, Olga DmitrenkoAbstract:Ab initio calculations at the G2, G3, and CBS-Q levels of theory have been applied to the question of the origin of Ring Strain in a series of unsaturated hydrocarbons. In addition to the angular Ring Strain germane to all three-membered Ring hydrocarbons, a general trend is in evidence that suggests that the increased Ring Strain (SE) of unsaturated small Ring alkenes may be attributed in part to their relatively weak allylic C-H bonds. The high Strain energy of cyclopropene (54.1 kcal/ mol) is attributed largely to angular Strain. The anomalously low SE of cyclobutene relative to cyclobutane (DeltaSE = 4 kcal/mol) is a consequence of normal C-H bond dissociation energies for cyclobutane (100.6 kcal/mol) and very strong vinyl C-H bonds (111.9 kcal/mol) and a relatively strong pi-bond energy (63.5 kcal/mol) for cyclobutene. The greater SE of methylenecyclopropane (39.5 kcal/ mol), relative to methylcyclopropane (29.8 kcal/mol), can be attributed to the strong Ring C-H bonds of methylcyclopropane (110.5 kcal/mol) and relatively weak allylic C-H bonds (99.3 kcal/mol) of methylenecyclopropane. The increased SE of 1-methylcyclopropene relative to isomeric methylenecyclopropane is ascribed to its weak Ring C-H bonds and to angular Strain. The relative thermodynamic stability of a series of small Ring alkenes is determined by a measure of their hydrogenation enthalpies. Independent confirmation of the SEs of a series of substituted cyclopropenes is provided by their dimerization/combination with cyclopropane to form a six-membered Ring reference compound.
Thomas M Gilbert - One of the best experts on this subject based on the ideXlab platform.
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ab initio prediction of Ring Strain enthalpies of cyclic amine boranes
Tetrahedron Letters, 1998Co-Authors: Thomas M GilbertAbstract:Abstract Ring Strain enthalpies for a series of cyclic amine-boranes (1-azonia-2-boratacycloalkanes) were calculated from MP4(SDTQ)/6-31G ∗ //MP2/6-31G ∗ energies by the group equivalent method. Small Rings exhibit smaller RSEs than do the corresponding cycloalkanes; larger Rings exhibit RSEs essentially identical to those of the corresponding cycloalkanes.
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ab initio prediction of Ring Strain enthalpies of cyclic amine boranes
Tetrahedron Letters, 1998Co-Authors: Thomas M GilbertAbstract:Abstract Ring Strain enthalpies for a series of cyclic amine-boranes (1-azonia-2-boratacycloalkanes) were calculated from MP4(SDTQ)/6-31G ∗ //MP2/6-31G ∗ energies by the group equivalent method. Small Rings exhibit smaller RSEs than do the corresponding cycloalkanes; larger Rings exhibit RSEs essentially identical to those of the corresponding cycloalkanes.
John A Montgomery - One of the best experts on this subject based on the ideXlab platform.
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a complete basis set model chemistry iv an improved atomic pair natural orbital method
Journal of Chemical Physics, 1994Co-Authors: John A Montgomery, Joseph W Ochterski, George A PeterssonAbstract:An improved complete basis set‐quadratic configuration interaction/atomic pair natural orbital (CBS‐QCI/APNO) model is described in this paper. It provides chemical energy differences (i.e., D0 I.P., and E.A.) with a mean absolute error of 0.53 kcal/mol for the 64 first‐row examples from the G2 test set, and is computationally feasible for species with up to three first‐row atoms. A set of 20 CBS‐QCI/APNO bond dissociation energies of hydrocarbons also agree with known experimental values to within less than 1 kcal/mol. Calculations on the cyclopropenyl radical and cyclopropenylidene provide new dissociation energies which are in accord with an interpretation of the thermochemistry emphasizing Ring Strain and aromaticity.An improved complete basis set‐quadratic configuration interaction/atomic pair natural orbital (CBS‐QCI/APNO) model is described in this paper. It provides chemical energy differences (i.e., D0 I.P., and E.A.) with a mean absolute error of 0.53 kcal/mol for the 64 first‐row examples from the G2 test set, and is computationally feasible for species with up to three first‐row atoms. A set of 20 CBS‐QCI/APNO bond dissociation energies of hydrocarbons also agree with known experimental values to within less than 1 kcal/mol. Calculations on the cyclopropenyl radical and cyclopropenylidene provide new dissociation energies which are in accord with an interpretation of the thermochemistry emphasizing Ring Strain and aromaticity.
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a complete basis set model chemistry iv an improved atomic pair natural orbital method
Journal of Chemical Physics, 1994Co-Authors: John A Montgomery, Joseph W Ochterski, George A PeterssonAbstract:An improved complete basis set‐quadratic configuration interaction/atomic pair natural orbital (CBS‐QCI/APNO) model is described in this paper. It provides chemical energy differences (i.e., D0 I.P., and E.A.) with a mean absolute error of 0.53 kcal/mol for the 64 first‐row examples from the G2 test set, and is computationally feasible for species with up to three first‐row atoms. A set of 20 CBS‐QCI/APNO bond dissociation energies of hydrocarbons also agree with known experimental values to within less than 1 kcal/mol. Calculations on the cyclopropenyl radical and cyclopropenylidene provide new dissociation energies which are in accord with an interpretation of the thermochemistry emphasizing Ring Strain and aromaticity.
