α-Alkyl-α-aminosilanes. 2. A2H NMR study of organolithium stabilization by silicon and by phenyl in solution

Sieburth, Scott McN.; Somers, Joseph J.

doi:10.1016/0040-4020(96)00191-3

Cited by 12 publications

(6 citation statements)

References 21 publications

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“…These are nucleophilic substitution reactions at Si, and the carbanionic leaving groups were either protonated to result in overall desilylation, or were used in synthesis for formation of C–C bonds by combination with carbon electrophiles. However, such reactions are successful only under certain favorable circumstances, such as the following: (a) The leaving carbon is stabilized by a carbanion-stabilizing group, as in allyl- or propargylsilanes, or by another trialkylsilyl group. , (b) The leaving C atom is in a hybridization state better suited than sp 3 to accommodate a negative charge. For example, Si–C vinyl bonds (leaving C sp 2 ) and Si–C ethynyl bonds (sp) are cleaved by n Bu 4 NF; in highly basic THF solution, the latter reaction was even claimed to be catalytic in fluoride in the presence of an alkoxide .…”

Section: Degradation Of Organosiloxanesmentioning

confidence: 99%

Environmental Chemistry of Organosiloxanes

2014

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Section: Degradation Of Organosiloxanesmentioning

confidence: 99%

Environmental Chemistry of Organosiloxanes

2014

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“…For ring‐opening products from 14 , a silicon group is the sole anion‐stabilizing substituent. The ability of silicon to stabilize an α‐anion is well known, but the extent of this stabilization is limited . The absence of stereochemistry at the cyclopropanone carbonyl of 14 unfortunately does not allow a study of a conrotatory ring‐opening pathway for this cyclopropanone …”

Section: Methodsmentioning

confidence: 99%

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

2016

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Irradiation of a 1,3‐enyne tethered to a 2‐pyridone, in the presence of oxygen, leads to formation of a seven‐membered ring product, an overall [4+4−1] reaction. This transformation involves two unstable intermediates and a sequence of unusual reactions. An initial [4+4] photocycloaddition of the enyne with the pyridone yields a 1,2,5‐cyclooctatriene. Photooxidation of this triene forms a cyclopropanone and subsequent photoextrusion of carbon monoxide gives the observed 1,4‐cycloheptadiene product. The first‐formed cyclooctatriene and the cyclopropanone could be observed and characterized spectroscopically. The cyclopropanone underwent CO extrusion both photochemically and thermally to give the cycloheptadiene product. Addition of fluoride or acetylide to the most stable cyclopropanone occurred chemoselectively at the two different silicon groups rather than the carbonyl group. The resulting cyclopropanone ring openings gave unsaturated aldehydes.

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“…[28,29] In many cases,a nion-stabilizing substituents on the termini of the allyl anion intermediate have been required. [30] Theabsence of stereochemistry at the cyclopropanone carbonyl of 14 unfortunately does not allow as tudy of ac onrotatory ring-opening pathway for this cyclopropanone. Theability of silicon to stabilize an aanion is well known, but the extent of this stabilization is limited.…”

Section: Angewandte Chemiementioning

confidence: 99%

“…Theability of silicon to stabilize an aanion is well known, but the extent of this stabilization is limited. [30] Theabsence of stereochemistry at the cyclopropanone carbonyl of 14 unfortunately does not allow as tudy of ac onrotatory ring-opening pathway for this cyclopropanone. [29,31] Fort he unusual 1,2,5-cyclooctatrienes discussed here, oxidation of the allene,e ither with dioxirane or by photocycloaddition in the presence of oxygen, results in isomerization to the corresponding cyclopropanone.W eh ave not observed oxidation of the more stable allenes,s uch as 8,o n exposure to oxygen in the absence of light.…”

Section: Angewandte Chemiementioning

confidence: 99%

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

2016

Self Cite

View full text Add to dashboard Cite

Irradiation of a 1,3-enyne tethered to a 2-pyridone, in the presence of oxygen, leads to formation of a seven-membered ring product, an overall [4+4-1] reaction. This transformation involves two unstable intermediates and a sequence of unusual reactions. An initial [4+4] photocycloaddition of the enyne with the pyridone yields a 1,2,5-cyclooctatriene. Photooxidation of this triene forms a cyclopropanone and subsequent photoextrusion of carbon monoxide gives the observed 1,4-cycloheptadiene product. The first-formed cyclooctatriene and the cyclopropanone could be observed and characterized spectroscopically. The cyclopropanone underwent CO extrusion both photochemically and thermally to give the cycloheptadiene product. Addition of fluoride or acetylide to the most stable cyclopropanone occurred chemoselectively at the two different silicon groups rather than the carbonyl group. The resulting cyclopropanone ring openings gave unsaturated aldehydes.

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α-Alkyl-α-aminosilanes. 2. A2H NMR study of organolithium stabilization by silicon and by phenyl in solution

Cited by 12 publications

References 21 publications

Environmental Chemistry of Organosiloxanes

Environmental Chemistry of Organosiloxanes

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

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