Neighboring group participation effects in the solvolysis of isobutyl and neopentyl sulfonate esters

Shiner, V. J.; Seib, R. C.

doi:10.1016/s0040-4039(01)85900-1

Cited by 6 publications

(3 citation statements)

References 11 publications

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“…Competing with this cation-forming k Δ process is a small amount of the k s process which leads to the 9% unrearranged product 11 . Previous solvolytic studies on triflate 9 in protic solvents gave only rearranged products . The formation of unrearranged 11 attests to the relatively high nucleophilicity of DMSO- d 6 even though carbocation formation in DMSO- d 6 is quite facile.…”

Section: Resultsmentioning

confidence: 86%

“…We were therefore interested in the kinetic behavior of the related triflates 9 and 14 . Neopentyl triflate 9 readily solvolyzes in DMSO- d 6 at 25 °C by a pseudo-first-order process readily monitored by 19 F NMR, where it is converted to a mixture of oxosulfonium ions 10 and 11 which are observable by 1 H NMR spectroscopy. As the reaction progresses at 25 °C, the oxosulfonium ion 10 converts to the alkenes 12 and 13 .…”

Section: Resultsmentioning

confidence: 99%

“…Preparation of Triflates. The preparations of triflates 5 , 9 , 21 , 23 , 24 , 25 , 29 , 33 ,11a and 39 15 have previously been described, as has the preparation of t -BuCH(OMs)CO- t -Bu ( 44 ) …”

Section: Methodsmentioning

confidence: 99%

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Remarkably Facile Solvolyses of Triflates via Carbocationic Processes in Dimethyl Sulfoxide

Creary

Burtch

2004

J. Org. Chem.

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A number of triflates have been shown to undergo clean pseudo-first-order solvolysis reactions in DMSO-d(6) to give products derived from carbocationic intermediates. Thus, t-BuCH(OTf)CO-t-Bu (5) and t-BuCH(2)OTf (9) react readily in DMSO-d(6) at 25 degrees C to give a rearranged oxosulfonium salts, and subsequent alkene products where methyl migration to the incipient cationic center occurs. t-BuCH(OTf)CO(2)CH(3) (14) gives analogous rearranged products, and 1-methylcyclopropyl triflate (21) gives a ring-opened allylic oxosulfonium salt. These triflates react primarily via k(Delta) pathways. 6-Methylbicyclo[3.1.0]hex-6-yl triflate (23), bicyclo[2.2.1hept-1-yl triflate (24), 1,6-methano[10]annulen-11-yl triflate (25), (CH(3))(2)C(OTf)CO(2)CH(3) (26), and (CH(3))(2)CCN(OTf) (29) all react in DMSO-d(6) to give carbocation-derived products. PhCH(OTf)CF(3) (33) and substituted analogues also react readily in DMSO-d(6), and the Hammett rho(+) value is -3.7. This suggests a "borderline" mechanism where the transition state has substantial charge development. The primary feature of these solvolyses is the high reactivity of all of these triflates in DMSO-d(6). Thus, these triflates are all more reactive in DMSO-d(6) than in HOAc, and for most, rates are faster than in CF(3)CH(2)OH. Triflates 5, 21, 29, and 33 are 10(8)-10(9) times more reactive in DMSO-d(6) than the corresponding mesylates. It is suggested that the decreased need for electrophilic solvation of triflate anion, and the high cation solvating ability of DMSO, are the reasons for the high triflate reactivity in DMSO-d(6).

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Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 99%

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Remarkably Facile Solvolyses of Triflates via Carbocationic Processes in Dimethyl Sulfoxide

Creary

Burtch

2004

J. Org. Chem.

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Nucleophilic substitution at saturated carbon atoms. Mechanisms and mechanistic borderlines: Evidence from studies with neutral leaving groups

Katritzky¹,

Brycki²

1988

J of Physical Organic Chem

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Substrates with neutral leaving groups undergo unimolecular solvolysis in nonpolar solvents. Whereas t-alkyl substrates invariably solvolyze by a unimolecular mechanism, .r-alkyl and primary alkyl substrates can undergo both uni and bimolecular reactions, and the bimolecular step can take place on either the substrate itself or on an intimate ion-molecule pair formed in either a pre-equilibrium or in a rate determining step. Study of reactions at borderlines indicates that the individual reaction types remain distinct and d o not merge.

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Assistance d'un groupe voisin pour des tosylates secondaires β substitues diequatoriaux dans l'hexafluoroisopropanol 97%

Laureillard

1984

Tetrahedron

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Neighboring group participation effects in the solvolysis of isobutyl and neopentyl sulfonate esters

Cited by 6 publications

References 11 publications

Remarkably Facile Solvolyses of Triflates via Carbocationic Processes in Dimethyl Sulfoxide

Remarkably Facile Solvolyses of Triflates via Carbocationic Processes in Dimethyl Sulfoxide

Nucleophilic substitution at saturated carbon atoms. Mechanisms and mechanistic borderlines: Evidence from studies with neutral leaving groups

Assistance d'un groupe voisin pour des tosylates secondaires β substitues diequatoriaux dans l'hexafluoroisopropanol 97%

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