- Regio- and sterochemistry of alkylation of benzoate anion with 5-phenyl 2-cyclohexenyl sulfonium salts : influence of copper(I)
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In order to invstigate the regio and stereochemistry of uncatalyzed and copper(I) catalyzed substitution reactions on allylic sulfonium salts, cis and trans 5-phenyl 2-cyclohexenyldimethylsulfonium tetrafluoroborates were synthesized, along with their α and γ-deutterated analogs.Uncatalyzed substitution of benzoate anion on these substrates essentially involves anti α attack (SN2 reaction), with a minor amount of syn γ (SN2') reaction in the case of the trans substrate.On the contrary, for both stereoisomers copper(I) catalyzed benzoate substitution displays anti attack with (50:50) α,γ-regiochemistry.The mechanism of this copper(I) catalyzed reaction is discussed: it necessarily involves a symmetrical intermediate, possibly a ?-allyl copper complex.
- Gauchet, Frederic,Julia, Marc,Mestdagh, Helene,Rolando, Christian
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p. 1036 - 1044
(2007/10/02)
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