Factors Influencing the Direction of Elimination in the Chugaev Reaction

Benkeser, Robert A.; Hazdra, James J.

doi:10.1021/ja01510a052

Cited by 30 publications

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“…All the polymers demonstrated thermal stability up to 250 °C, at which point they underwent a partial mass loss before reaching a plateau and fully degrading at >400 °C (Figure C). We hypothesized that this partial mass loss was the result of a Chugaev-type elimination. , To support this hypothesis, the evolution of volatile compounds accompanying the partial mass loss was analyzed by mass spectrometry (TGA/MS). A prominent peak at a mass to charge ( m / z ) of 76.1 was evident in all of the samples, which we hypothesize is due to expulsion of carbon disulfide.…”

Section: Resultsmentioning

confidence: 99%

“…We hypothesized that this partial mass loss was the result of a Chugaev-type elimination. 50,51 To support this hypothesis, the evolution of volatile compounds accompanying the partial mass loss was analyzed by mass spectrometry (TGA/MS). A prominent peak at a mass to charge (m/z) of 76.1 was evident in all of the samples, which we hypothesize is due to expulsion of carbon disulfide.…”

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

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Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure–Property Study

Williamson

Johnson

et al. 2019

J. Am. Chem. Soc.

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Polyolefins represent a high-volume class of polymers prized for their attractive thermomechanical properties, but the lack of chemical functionality on polyolefins makes them inadequate for many high-performance engineering applications. We report a metal-free postpolymerization modification approach to impart functionality onto branched polyolefins without the deleterious chain-coupling or chain-scission side reactions inherent to previous methods. The identification of conditions for thermally initiated polyolefin C−H functionalization combined with the development of new reagents enabled the addition of xanthates, trithiocarbonates, and dithiocarbamates to a variety of commercially available branched polyolefins. Systematic experimental and kinetic studies led to a mechanistic hypothesis that facilitated the rational design of reagents and reaction conditions for the thermally initiated C−H xanthylation of isotactic polypropylene (iPP) within a twin-screw extruder. A structure−property study showed that the functionalized iPP adheres to polar surfaces twice as strongly as commercial iPP while demonstrating similar tensile properties. The fundamental understanding of the elementary steps in amidyl radical-mediated polyolefin functionalization provided herein reveals key structure−reactivity relationships for the design of improved reagents, while the demonstration of chemoselective and scalable iPP functionalization to realize a material with improved adhesion properties indicates the translational potential of this method.

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Section: Resultsmentioning

confidence: 99%

Section: Journal Of the American Chemical Societymentioning

confidence: 99%

Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure–Property Study

Williamson

Johnson

et al. 2019

J. Am. Chem. Soc.

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“…These base-free coupling conditions also tolerate protic functional groups ( 3f , 3h ), where many analogous, benzyl-derived pronucleophiles (e.g., BnBF 3 K or BnZnCl, derived from benzyl halides), in contrast, would be difficult to prepare directly in their unprotected form. Secondary benzyl and unactivated alkyl xanthates (Chugaev elimination product could be observed) were not well-tolerated in these studies, even upon mild heating, and often resulted in a mixture of products.…”

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confidence: 89%

O-Benzyl Xanthate Esters under Ni/Photoredox Dual Catalysis: Selective Radical Generation and Csp³–Csp² Cross-Coupling

2017

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Alkyl xanthate esters are perhaps best known for their use in deoxygenation chemistry. However, their use in cross-coupling chemistry has not been productive, which is due, in part, to inadequate xanthate activation strategies. Herein, we report the use of O-benzyl xanthate esters, readily derived from alcohols, as radical pronucleophiles in Csp3–Csp2 cross-couplings under Ni/photoredox dual catalysis. Xanthate (C–O) cleavage is found to be reliant on photogenerated (sec-butyl) radical activators to form new carbon-centered radicals primed for nickel-catalyzed cross-couplings. Mechanistic experiments support the fact that the key radical components are formed independently, and relative rates are carefully orchestrated, such that no cross reactivity is observed.

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“…Moreover there is eclipsing in these alkene products, which is greatest for the cyclohexyl derivative (and compounded by the fact that the a-Me-ring C-H bond distance is shorter in this product). Consequently less of this alkene is formed from ester (34) than from the corresponding cyclopentyl ester (33).…”

Section: E V I Ementioning

confidence: 99%

The transition state in ester pyrolysis. Part 9. On the ‘surface-catalysed’ mechanism for the elimination

Taylor¹

1979

J. Chem. Soc., Perkin Trans. 2

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Factors Influencing the Direction of Elimination in the Chugaev Reaction

Cited by 30 publications

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Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure–Property Study

Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure–Property Study

O-Benzyl Xanthate Esters under Ni/Photoredox Dual Catalysis: Selective Radical Generation and Csp³–Csp² Cross-Coupling

The transition state in ester pyrolysis. Part 9. On the ‘surface-catalysed’ mechanism for the elimination

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Factors Influencing the Direction of Elimination in the Chugaev Reaction

Cited by 30 publications

References 0 publications

Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure–Property Study

Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure–Property Study

O-Benzyl Xanthate Esters under Ni/Photoredox Dual Catalysis: Selective Radical Generation and Csp3–Csp2 Cross-Coupling

The transition state in ester pyrolysis. Part 9. On the ‘surface-catalysed’ mechanism for the elimination

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O-Benzyl Xanthate Esters under Ni/Photoredox Dual Catalysis: Selective Radical Generation and Csp³–Csp² Cross-Coupling