Degenerate rearrangements of long-lived 9,10-dimethyl-9-(1-methyl-1-vinyl)-phenanthrenium and 9,10-dimethyl-9-(trans-1-methyl-1-propenyl)phenanthrenium ions: unexpected strong retardation of vinyl migrations

Artamoshkin, V. G.; Bushmelev, V. A.; Genaev, A. M.; Shubin, V. G.

doi:10.1070/mc2006v016n02abeh002209

Cited by 4 publications

(3 citation statements)

References 2 publications

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“…A very sharp (by five orders of magnitude) slowing down of the degenerate rearrangement going from cation 1c to 1d, 28,29 i.e., when the cis dimethylvinyl migrant was replaced by the trans dimethylvinyl one, turned out to be quite unexpected. Geometric characteristics of the initial and transition states of the rearrangements have been obtained 29 by the DFT method ("PRIRODA" program 34, 35 ).…”

Section: Methodsmentioning

confidence: 91%

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Long-lived cationic complexes: “frozen” intermediates of cationoid reactions

Shubin

2008

Russ Chem Bull

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Section: Methodsmentioning

confidence: 91%

“…68 A rapid de generate rearrangement is also characteristic of this com plex ( Scheme 14). As X ray analysis shows, nitrosonium complex of 1,10 phenanthroline in the solid state (crys talline tetrafluoroborate), in contrast to the dynamic monodentate n complex 27 in solution, is a static biden tate one (28). 69,70…”

Section: Scheme 13mentioning

confidence: 97%

Long-lived cationic complexes: “frozen” intermediates of cationoid reactions

Shubin

2008

Russ Chem Bull

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“…This slow migration has not been explained. 40 [1,3]-Sigmatropic migrations of the nitroso group in the systems ON-X-CH=X (X = O, S, Se, NH, CH 2 ) have been studied by DFT methods. 41 Treatment of silyl ethers of allyl alcohol, and some simple derivatives, with t-BuLi in THF-HMPA, followed by a suitable electrophile, has been shown to give the 1,4-retro-Brook rearrangement products, which are ethers, carbonates or carbamates of 3-trialkylsilylprop-1-en-1-ol.…”

Section: [1n]-sigmatropic Rearrangementsmentioning

confidence: 99%

Molecular Rearrangements: Part 1. Pericyclic Reactions

Armstrong

2010

Organic Reaction Mechanisms · 2006

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Energy barriers to degenerate rearrangements of long-lived carbocations: Quantum chemical calculations vs. experiment

Genaev

Shubin

2006

Russ Chem Bull

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Density functional calculations of energy barriers to degenerate rearrangements of long lived carbocations that occur by 1,2 shifts of various atoms and groups were performed. The results obtained were compared with the available experimental data. Good agreement was found for hydrocarbon migrants. Possible reasons of discrepancies in the case of hydrogen migrant and migrants containing heteroatoms are discussed.Rearrangements of carbocations generated in super acids (so called long lived carbocations) have a high syn thetic potential. A number of relevant examples are shown in Scheme 1. Such rearrangements result in cations with other cyclic systems, occur at room temperature, and pro vide a nearly quantitative yield of the products obtained upon neutralization of acid solutions. 1-4 However, at present these reactions are not used for synthetic purposes because of low predictability of their results owing to mul tistage character and very large number of possible path ways. Each pathway includes a sequence of one step pro cesses, among which the 1,2 shifts of migrants or σ bonds to a neighboring carbocationic center play the key role.The possibility for the rearrangements of initial and inter mediate carbocations to follow several pathways leads to branched reaction schemes (graphs) containing tens of structures. 5 An ICAR program 6 permits automated con struction of such graphs. 7 In order to predict the results of a rearrangement, one should estimate the relative stability of each structure and the activation barriers to corre sponding reaction paths. Evaluation based on the avail able experimental data is only reliable for close analogs. The molecular mechanics and semiempirical quantum chemical methods are almost inapplicable for the activa tion barrier calculations, while the ab initio methods are time consuming. In this situation good results can be obtained from density functional quantum chemical cal culations using recently developed, fast and efficient pro grams, e.g., the PRIRODA program. 8 * Dedicated to the memory of Academician V. A. Koptyug on the occasion of the 75th anniversary of his birth.

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Degenerate rearrangements of long-lived 9,10-dimethyl-9-(1-methyl-1-vinyl)-phenanthrenium and 9,10-dimethyl-9-(trans-1-methyl-1-propenyl)phenanthrenium ions: unexpected strong retardation of vinyl migrations

Cited by 4 publications

References 2 publications

Long-lived cationic complexes: “frozen” intermediates of cationoid reactions

Long-lived cationic complexes: “frozen” intermediates of cationoid reactions

Molecular Rearrangements: Part 1. Pericyclic Reactions

Energy barriers to degenerate rearrangements of long-lived carbocations: Quantum chemical calculations vs. experiment

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