Regioselectivity in the Reductive Bond Cleavage of Diarylalkylsulfonium Salts: Variation with Driving Force andStructure of Sulfuranyl Radical Intermediates

Jack Kampmeier, AKM Mansurul Hoque, Franklin D. Saeva, Donald K. Wedergaertner, Pia Thomsen, Saif Ullah, Jacob Krake, Torben Lund

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

This investigation was stimulated by reports that one-electron reductions of monoaryldialkylsulfonium
salts never give aryl bond cleavage whereas reductions of diarylmonoalkylsulfonium salts
preferentially give aryl bond cleavage. We studied the product ratios from the reductive cleavage of di-4-
tolylethylsulfonium and di-4-tolyl-2-phenylethylsulfonium salts by a variety of one-electron reducing agents
ranging in potential from -0.77 to +2.5 eV (vs SCE) and including thermal reductants, indirect electrolyses
mediated by a series of cyanoaromatics, and excited singlet states. We report that the cleavage products
vary from regiospecific alkyl cleavage to predominant aryl cleavage as a function of the potential of the
reducing agent. We conclude that differences between the reductive cleavages of mono- and diarylsulfonium
salts are direct consequences of the structures of the sulfuranyl radical intermediates and the bond
dissociation energies of the alkyl and aryl bonds. Competitions between the rates of cleavage and oxidation
of the intermediate sulfuranyl radicals and between concerted and stepwise mechanisms are discussed to
explain the variations in bond cleavage products as a function of the driving forces for the reductions.
Density functional theory investigations of the nature of the antibonding S-alkyl and S-aryl orbitals of the
starting sulfonium salts provide additional insight.
OriginalsprogEngelsk
TidsskriftJournal of the American Chemical Society
Vol/bind131
Udgave nummer29
Sider (fra-til)10015-10022
Antal sider8
ISSN0002-7863
DOI
StatusUdgivet - 2009

Emneord

  • Sulfonium salte
  • reduktion
  • fraspaltning af alkyl/phenyl radikaler

Citer dette

Kampmeier, Jack ; Mansurul Hoque, AKM ; D. Saeva, Franklin ; K. Wedergaertner, Donald ; Thomsen, Pia ; Ullah, Saif ; Krake, Jacob ; Lund, Torben. / Regioselectivity in the Reductive Bond Cleavage of Diarylalkylsulfonium Salts : Variation with Driving Force andStructure of Sulfuranyl Radical Intermediates. I: Journal of the American Chemical Society. 2009 ; Bind 131, Nr. 29. s. 10015-10022.
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abstract = "This investigation was stimulated by reports that one-electron reductions of monoaryldialkylsulfoniumsalts never give aryl bond cleavage whereas reductions of diarylmonoalkylsulfonium saltspreferentially give aryl bond cleavage. We studied the product ratios from the reductive cleavage of di-4-tolylethylsulfonium and di-4-tolyl-2-phenylethylsulfonium salts by a variety of one-electron reducing agentsranging in potential from -0.77 to +2.5 eV (vs SCE) and including thermal reductants, indirect electrolysesmediated by a series of cyanoaromatics, and excited singlet states. We report that the cleavage productsvary from regiospecific alkyl cleavage to predominant aryl cleavage as a function of the potential of thereducing agent. We conclude that differences between the reductive cleavages of mono- and diarylsulfoniumsalts are direct consequences of the structures of the sulfuranyl radical intermediates and the bonddissociation energies of the alkyl and aryl bonds. Competitions between the rates of cleavage and oxidationof the intermediate sulfuranyl radicals and between concerted and stepwise mechanisms are discussed toexplain the variations in bond cleavage products as a function of the driving forces for the reductions.Density functional theory investigations of the nature of the antibonding S-alkyl and S-aryl orbitals of thestarting sulfonium salts provide additional insight.",
keywords = "Sulfonium salte, reduktion, fraspaltning af alkyl/phenyl radikaler",
author = "Jack Kampmeier and {Mansurul Hoque}, AKM and {D. Saeva}, Franklin and {K. Wedergaertner}, Donald and Pia Thomsen and Saif Ullah and Jacob Krake and Torben Lund",
year = "2009",
doi = "10.1021/ja809918k",
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volume = "131",
pages = "10015--10022",
journal = "Journal of the American Chemical Society",
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Regioselectivity in the Reductive Bond Cleavage of Diarylalkylsulfonium Salts : Variation with Driving Force andStructure of Sulfuranyl Radical Intermediates. / Kampmeier, Jack; Mansurul Hoque, AKM; D. Saeva, Franklin; K. Wedergaertner, Donald; Thomsen, Pia; Ullah, Saif; Krake, Jacob; Lund, Torben.

I: Journal of the American Chemical Society, Bind 131, Nr. 29, 2009, s. 10015-10022.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Regioselectivity in the Reductive Bond Cleavage of Diarylalkylsulfonium Salts

T2 - Variation with Driving Force andStructure of Sulfuranyl Radical Intermediates

AU - Kampmeier, Jack

AU - Mansurul Hoque, AKM

AU - D. Saeva, Franklin

AU - K. Wedergaertner, Donald

AU - Thomsen, Pia

AU - Ullah, Saif

AU - Krake, Jacob

AU - Lund, Torben

PY - 2009

Y1 - 2009

N2 - This investigation was stimulated by reports that one-electron reductions of monoaryldialkylsulfoniumsalts never give aryl bond cleavage whereas reductions of diarylmonoalkylsulfonium saltspreferentially give aryl bond cleavage. We studied the product ratios from the reductive cleavage of di-4-tolylethylsulfonium and di-4-tolyl-2-phenylethylsulfonium salts by a variety of one-electron reducing agentsranging in potential from -0.77 to +2.5 eV (vs SCE) and including thermal reductants, indirect electrolysesmediated by a series of cyanoaromatics, and excited singlet states. We report that the cleavage productsvary from regiospecific alkyl cleavage to predominant aryl cleavage as a function of the potential of thereducing agent. We conclude that differences between the reductive cleavages of mono- and diarylsulfoniumsalts are direct consequences of the structures of the sulfuranyl radical intermediates and the bonddissociation energies of the alkyl and aryl bonds. Competitions between the rates of cleavage and oxidationof the intermediate sulfuranyl radicals and between concerted and stepwise mechanisms are discussed toexplain the variations in bond cleavage products as a function of the driving forces for the reductions.Density functional theory investigations of the nature of the antibonding S-alkyl and S-aryl orbitals of thestarting sulfonium salts provide additional insight.

AB - This investigation was stimulated by reports that one-electron reductions of monoaryldialkylsulfoniumsalts never give aryl bond cleavage whereas reductions of diarylmonoalkylsulfonium saltspreferentially give aryl bond cleavage. We studied the product ratios from the reductive cleavage of di-4-tolylethylsulfonium and di-4-tolyl-2-phenylethylsulfonium salts by a variety of one-electron reducing agentsranging in potential from -0.77 to +2.5 eV (vs SCE) and including thermal reductants, indirect electrolysesmediated by a series of cyanoaromatics, and excited singlet states. We report that the cleavage productsvary from regiospecific alkyl cleavage to predominant aryl cleavage as a function of the potential of thereducing agent. We conclude that differences between the reductive cleavages of mono- and diarylsulfoniumsalts are direct consequences of the structures of the sulfuranyl radical intermediates and the bonddissociation energies of the alkyl and aryl bonds. Competitions between the rates of cleavage and oxidationof the intermediate sulfuranyl radicals and between concerted and stepwise mechanisms are discussed toexplain the variations in bond cleavage products as a function of the driving forces for the reductions.Density functional theory investigations of the nature of the antibonding S-alkyl and S-aryl orbitals of thestarting sulfonium salts provide additional insight.

KW - Sulfonium salte

KW - reduktion

KW - fraspaltning af alkyl/phenyl radikaler

U2 - 10.1021/ja809918k

DO - 10.1021/ja809918k

M3 - Journal article

VL - 131

SP - 10015

EP - 10022

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 29

ER -