Theoretical studies of the structures and reactions of substituted carbonyl ylides

Houk, K. N.; Rondan, Nelson G.; Santiago, Cielo; Gallo, Catherine J.; Gandour, Ruth Wells; Griffin, G. W.

doi:10.1021/ja00525a006

Cited by 67 publications

(35 citation statements)

References 23 publications

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“…From Table 3, the energy splitting among six biradical states of 1 are not so dependent on the basis sets employed. But this fact is far different from the closed-shell RHF MO [4] and RHF CI [5] results. The present calculations indicate that the d-polarization functions are not crucial for calculations of the rotational energy barriers of 1.…”

Section: Energy Levels Rotational Energy Barriers and Orbital Energiescontrasting

confidence: 77%

“…Elegant experiments by Huisgen showed that the energy barrier, for the isomerization from the cis edge-to-edge (EE) form to the trans EE form of the carbonyl ylides formed from C-C cleavaged α-cyanostilbene oxide, is 8-16 kcal mol −1 [2]. The energy barrier for one of the terminal methylene groups of the parent carbonyl ylide CH 2 OCH 2 1 was calculated, by theoretical studies, to be 14 (4-31G basis set) kcal mol −1 by Hehre [3], 63 and 39 (4-31G) kcal mol −1 by Houk et al [4] and 13-17 (4-31G) kcal mol −1 by Jean and Volatron [5]. These results indicate that the calculated energy barriers are highly dependent on the computational methods even if the same basis set is employed.…”

Section: Introductionmentioning

confidence: 99%

“…Houk et al [4] have utilized the closed-shell restricted Hartree-Fock (RHF) solutions to compute the energy difference between EE and face-to-edge (FE) forms of carbonyl ylide 1. The use of 3 × 3 configuration interaction (CI) did not lower the rotational barrier obtained from the RHF results.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical study on rotational barriers of 1,3‐dipoles and mechanisms of 1,3‐dipolar reactions

Yoshioka

Yamaki

Kiribayashi

et al. 1997

Elect J Theoret Chem

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SUMMARYThe different orbitals for different spins molecular orbital and complete active space (CAS) SCF MO descriptions of azomethyne ylides, carbonyl ylides and related oxygenated dipoles were performed as a continuation of earlier papers. Rotational energy barriers for the C-C double bond of ethylene at the equilibrium and dissociated geometries, and the 1,3-dipolar species were calculated by UHF, APUHF, UMP, APUMPn, CASSCF and CASSCF MP2 procedures, and were discussed in relation to their biradical characters and stereospecificity of 1,3-dipolar reactions. It was found that the biradical characters of carbonyl ylides and related species are quenched by the symmetry-allowed orbital interactions with olefins, in accord with the symmetry-allowed concerted property. The rotational energy barriers for 1,5 biradicals were also examined in relation to the non-concerted mechanism of 1,3-dipolar reactions. The implications of these results are discussed in relation to the concerted and biradical mechanisms of 1,3-dipolar additions such as ozonolysis reactions.

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Section: Energy Levels Rotational Energy Barriers and Orbital Energiescontrasting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Theoretical study on rotational barriers of 1,3‐dipoles and mechanisms of 1,3‐dipolar reactions

Yoshioka

Yamaki

Kiribayashi

et al. 1997

Elect J Theoret Chem

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“…In neat 5, only about 27% of the ylide generated from 1 was trapped as the cycloadduct 9 at 79.5"C (eq. [12]). …”

Section: Andoch3mentioning

confidence: 99%

“…Fragmentation (eq. [6]) appears to require, at one reactive site of the ylide, a substituent, such as arnino or alkoxy, capable of conjugative donation of electron density (2,12).…”

Section: Introductionmentioning

confidence: 99%

Carbonyl ylides and carbenes from thermolysis of oxadiazolines. Substituent effects on intramolecular and intermolecular reactions of carbonyl ylides

Bekhazi¹,

Warkentin²

1983

Can. J. Chem.

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Thermolysis of a 2-methoxy-Δ3-1,3,4-oxadiazoline involves loss of N2 with formation of a carbonyl ylide. The fate of the carbonyl ylide depends on its environment and on the other substituents present. Thus, the ylides from 2-methoxy-2,5,5-trimethyl-Δ3-1,3,4-oxadiazoline (1) and from 2-methoxy-2-(4-methoxyphenyl)-5,5-dimethyl-Δ3-1,3,4-oxadiazoline (2) are trapped very efficiently by methanol. However, the ylide from 1 is trapped much less efficiently than that from 2 by dimethylacetylene dicarboxylate, cis-1,2-dichloroethylene, or norbornadiene. A major competitive process in the case of 1 is fragmentation of the ylide to carbonyl compounds and carbenes, the latter being trapped by alkenes to form cyclopropanes. An intramolecular 1,4-H transfer is also competitive under some conditions. The ylide from 2 does not appear to fragment, nor does it undergo the 1,4-H transfer, but it cyclizes efficiently to the oxirane in the absence of trapping agents.Preliminary estimates of rate constants for cyclization of the ylide from 2 to form the oxirane [Formula: see text] and for its additions to norbornadiene and to dimethylacetylene dicarboxylate (1 × 105 M−1 s−1 and 1 × 109 M−1 s−1, respectively) are reported. If it is assumed that the ylide from 1 would add to dimethylacetylene dicarboxylate with a similar rate constant, then the yield for that process can be used to place a lower limit of 1010 s−1 on the rate constant for fragmentation of that ylide at 31 °C.

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Direct observation of the ylides formed upon reaction of cyclopentadienylidene with acetic anhydride, dimethyl carbonate, ethyl acetate and acetone

Platz

Olson

1996

J. Phys. Org. Chem.

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Cyclopentadienylidene was studied by laser Rash photolysis (LFP) techniques. LFP of diazocyclopentadiene in acetic anhydride, acetaldehyde, acetone, dimethyl carbonate, ethyl acetate, acetonitrile, dimethyl sulfide and pyridine produces UV-visible active ylides. The first reports of the direct detection of carbene--anhydride, carbene-aldehyde, carbene-amide and carbene-carbonate ylides are presented. The spectra and the lifetimes of these ylides are reported.

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Theoretical studies of the structures and reactions of substituted carbonyl ylides

Cited by 67 publications

References 23 publications

Theoretical study on rotational barriers of 1,3‐dipoles and mechanisms of 1,3‐dipolar reactions

Theoretical study on rotational barriers of 1,3‐dipoles and mechanisms of 1,3‐dipolar reactions

Carbonyl ylides and carbenes from thermolysis of oxadiazolines. Substituent effects on intramolecular and intermolecular reactions of carbonyl ylides

Direct observation of the ylides formed upon reaction of cyclopentadienylidene with acetic anhydride, dimethyl carbonate, ethyl acetate and acetone

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