Reaction of singlet oxygen with conformationally fixed cyclohexylidenecyclohexanes. Failure of an all suprafacial mechanism

Kellogg, Richard M.; Kaiser, Judy K.

doi:10.1021/jo00905a052

Cited by 14 publications

(5 citation statements)

References 2 publications

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“…(Orbital symmetry allowed) desulfurization to cis -1,2-di- t -butyl ethylene 6 proceeded cleanly. The cis -isomer of 3 obediently provided the trans -isomer of 6 . , …”

Section: Resultsmentioning

confidence: 99%

“…The cis-isomer of 3 obediently provided the transisomer of 6. 7,8 There are two workable routes to 1,3,4-thiadiazolines, the precursors of the thiocarbonyl ylides. They can be formed either by 1,3-dipolar reaction of a diazo compound with a thioketone (Scheme 2a) or by (oxidative) ring-closure of an azine with H 2 S, the route used in Scheme 1.…”

Section: ■ Resultsmentioning

confidence: 99%

“…This behavior is shown by both enantiomers as illustrated in Figure 3. Virtually identical behavior has been reported for P- [7]helicene. 87 From density functional theory (DFT) calculations, it was determined that the arrangement with the NH 2 group pointing toward the Au surface was approximately 3.4 kcal/mol more stable than the arrangement with the NH 2 group pointing away from the surface.…”

Section: ■ Resultsmentioning

confidence: 99%

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Practical Stereochemistry

Kellogg

2017

Acc. Chem. Res.

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The relationship between fundamental and applied is often uneasy, particularly in modern political climates. A familiar political view, aimed negatively at the scientific community, is that the former is a waste of money whereas the latter gives value for investment. The answer that fundamental is required as the basis for practical suffers from the fact that the timelines between fundamental and practical are often long and the routes contorted and unexpected. This has been my experience. In this Account, examples are given from the research in which I have been involved wherein quite fundamental considerations have led to various applications. The longer the time, the clearer and broader the relationship. Fundamental can and does lead to application. They need and depend on each other. I have seen this both from the side of academia and from small companies. In the course of the past 40 plus years, I have been involved in various aspects of stereochemistry and, in particular, chirality. It has been rewarding to see that several of the developments, most originally grounded in fundamental research considerations, have been used in the chemical community and given new dimensions and often practical applications by others. In this Account, a path-not planned deliberately by me-from orbital symmetry and Woodward-Hoffmann rules through crown ethers to conformational analysis to diastereomeric resolutions to deracemizations powered by Ostwald ripening and the Gibbs-Thomson effect to nucleation to helicenes is described. In order of discussion, the orbital symmetry aspects have via an unusual and unpredicted path has resulted in, among other things, a synthesis of hindered alkenes useful for the production of molecular motors. The crown ether aspects led to discovery of the utility of cesium salts particularly for racemization sensitive nucleophilic substitutions. Work on diastereomeric resolutions has concentrated on the mechanistic as well as practical/commercial aspects of the use of multiple resolving agents (Dutch resolution). During this work the complex relationship between nucleation and chirality in diastereomeric resolutions began to reveal itself. In general, nucleation, especially with involvement of chirality, is a topical challenge that has attracted the attention of many groups. The contribution of this knowledge to the development of attrition driven deracemizations of racemizable conglomerates is described. This remarkable technology allows, without intervention of chiral aids, conversion of certain racemates in quantitative yield and absolute enantiomeric excess to a single enantiomer. From a practical standpoint, this methodology has been used for the production in enantiomerically pure form of commercially interesting compounds like naproxen and clopidogrel (Plavix). Finally an STM investigation of the nucleation behavior of a helicene, prepared via a remarkably short and efficient route, on a metal surface is described.

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“…(Orbital symmetry allowed) desulfurization to cis -1,2-di- t -butyl ethylene 6 proceeded cleanly. The cis -isomer of 3 obediently provided the trans -isomer of 6 . , …”

Section: Resultsmentioning

confidence: 99%

Section: ■ Resultsmentioning

confidence: 99%

Section: ■ Resultsmentioning

confidence: 99%

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Practical Stereochemistry

Kellogg

2017

Acc. Chem. Res.

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“…To confirm the deviation from the predicted C2v symmetry (Kellogg & Kaiser, 1975), two different molecules were generated through a mirror plane perpendicular to the double bond with C1-C6 and C 11-C 16 ring conformations, respectively. Both models yielded, as expected, R factors as high as 0.50 and distances from atoms of different molecules shorter than van der Waals values.…”

Section: Discussionmentioning

confidence: 99%

Structure of syn-1-tert-butyl-4-(4-tert-butylcyclohexylidene)cyclohexane

Mariezcurrena¹,

Fornaro²

1988

Acta Crystallogr C

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“…Conformationally fixed C2" and CZh conformers of cyclohexylidenecyclohexane react with '02 to give in different ratio two stereoisomeric allylic hydroperoxides, a result not in accord with an all suprafacial mechanism for the "ene" reaction [40]. Reaction of '02 with germacratriene showed that the exocyclic isopropylidene double bond is nine times more reactive than the endocyclic double bond.…”

Section: On Generation Of ' 0 mentioning

confidence: 98%

Recent Developments in Singlet Molecular Oxygen Chemistry

Rosenthal

1976

Photochem & Photobiology

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This review is an attempt to summarize the literature pertinent to singlet molecular oxygen over the period June 1975-June 1976. Reports on this topic span a wide range of interests: from theoretical attempts to understand, and consequently predict, the interaction between '02 and organic materials, to applications of these reactions to complex biological systems. Although such a survey is necessarily heterogeneous and can hardly be exhaustive, it emphasizes the interdisciplinary aspects of this subject.

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Reaction of singlet oxygen with conformationally fixed cyclohexylidenecyclohexanes. Failure of an all suprafacial mechanism

Cited by 14 publications

References 2 publications

Practical Stereochemistry

Practical Stereochemistry

Structure of syn-1-tert-butyl-4-(4-tert-butylcyclohexylidene)cyclohexane

Recent Developments in Singlet Molecular Oxygen Chemistry

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