Intramolekulare [4 + 2]‐ und [3 + 2]‐Cycloadditionen in der organischen Synthese

Oppolzer, Wolfgang

doi:10.1002/ange.19770890105

Cited by 157 publications

(23 citation statements)

References 85 publications

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“…The even higher complexation constants of the pseudocryptand (3) for these divalent cations is especially striking; this compound has three terminal tropolone ether groups. In agreement with this, a BaIz complex of (3) could be isolated but a KSCN complex could not. In contrast, the complex stabilities for the smaller Lii and Caz+ ions are clearly lower.…”

supporting

confidence: 70%

Double Ring‐Closure Additions to o‐(Methyleneamino)‐phenyl Phosphites

Schmidpeter¹,

Weinmaier²,

Glaser³

1977

Angew. Chem. Int. Ed. Engl.

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supporting

confidence: 70%

Double Ring‐Closure Additions to o‐(Methyleneamino)‐phenyl Phosphites

Schmidpeter¹,

Weinmaier²,

Glaser³

1977

Angew. Chem. Int. Ed. Engl.

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“…13 C NMR spectra were recorded at 125.6 MHz by using a Bruker Avance 500 spectrometer. Coupling constants (J) are given in Hz.…”

Section: Methodsmentioning

confidence: 99%

“…Within complex [A·B], the juxtaposition of the reactive centers of A and B is attainable, rendering the reaction [13] between A and B pseudounimolecular. Intracomplex reactions of this sort are characterised by rate accelerations [14] of considerable magnitude, relative to the rate of random bimolecular collisions between A and B, and yield T inactive with a rate constant of k AB (k AB @ k bim ).…”

Section: Introductionmentioning

confidence: 99%

Comparative Analyses of a Family of Potential Self‐Replicators: The Subtle Interplay between Molecular Structure and the Efficacy of Self‐Replication

Pearson

Kassianidis

Slawin

et al. 2006

Chemistry A European J

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It is envisioned that protocols based on self-replication will emerge as a formidable synthetic apparatus for the production of nanoscale assemblies through molecular structures that are capable of automultiplication with high reaction rates and selectivities. To achieve this goal, a complete understanding of the relationship between molecular structure and replication efficiency is necessary. Rigorous experimental and theoretical analyses of a series of self-complementary scaffolds that are intimately related in a constitutional sense, manufactured through the Diels-Alder reaction of complementary subunits, were undertaken. Experimental and computational methods were employed to map the key determinants that dictate the emergence of self-replicative function, as well as the efficiency, rate and selectivity of the self-replicative processes.

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“…The elusiveness of the Z-isomers in chemical trapping experiments [2] is explained by their extremely rapid reketonization to starting material. Although the chances to use Z-dienols as reactive intermediates of synthetic interest are rather remote, they may be raised by using hydrogen-bondacceptor solvents such as DMSO, pyridine, or HMPA and highly reactive dienophiles in high concentrations or directly attached to the potential diene component [32]. Further work is needed to explain the photochemical behaviour of 2,6-dialkylphenyl ketones [3] [25].…”

mentioning

confidence: 99%

The Photoenolization of 2‐Methylacetophenone and Related Compounds

Haag¹,

Wirz²,

Wagner³

1977

Helvetica Chimica Acta

195

141

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SummaryA reinvestigation of 2-methylacetophenone (1) by ns flash photolysis has provided detailed evidence for the reaction sequence of photoenolization. The triplet reaction proceeds adiabatically from the lowest excited triplet state of the ketone, 3K (l), to the enol excited triplet state, 3E (l), which decays both to enol and ketone ground state. The Z-and E-isomers of the photoenol, Z-E (1) and E-E (1) are formed in about equal yield by the triplet pathway, while direct enolization from the lowest excited singlet state of 1 yields (predominantly) the 2-isomer. Intramolecular reketonization from 2-E (1) to 1 proceeds at a rate of ca. loss-' in cyclohexane, but can be retarded to ca. 104s-' in hydrogen-bond-acceptor solvents. The proposed mechanism is summarized in Scheme 1 and rationalized on the basis of a state correlation diagram, Scheme 2. 3,3,6,8-Tetramethyl-l-tetralone (2) was used as a reference compound with fixed conformational position of the carbonyl group, and some results from a brief investigation of 2,4-dimethylbenzophenone (3) are also reported.We have recently found [ 11 that the photoenolization of 5-methyl-l,6naphtho-quinone takes place with high efficiency and that the thermal reketonization to starting material is very fast at room temperature. The great retardation of the back reaction from a rate of ca. 105s-' in cyclohexane to ca. lo's-' in hexamethyl phosphoric acid triamide (HMPA) was striking but not surprising: The solvation of the enolic proton in hydrogen-bond-acceptor (HBA) solvents obviously provides an I)

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Intramolekulare [4 + 2]‐ und [3 + 2]‐Cycloadditionen in der organischen Synthese

Cited by 157 publications

References 85 publications

Double Ring‐Closure Additions to o‐(Methyleneamino)‐phenyl Phosphites

Double Ring‐Closure Additions to o‐(Methyleneamino)‐phenyl Phosphites

Comparative Analyses of a Family of Potential Self‐Replicators: The Subtle Interplay between Molecular Structure and the Efficacy of Self‐Replication

The Photoenolization of 2‐Methylacetophenone and Related Compounds

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