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Thermodynamic stability and reactivity of silylated bis(oxy)iminium ions.

Khomutova YA, Smirnov VO, Mayr H, Ioffe SL

ND Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospekt 47, 119991, Moscow, Russian Federation.

Silylation of various nitronates with trialkylsilyl triflates was investigated by applying NMR techniques. In several cases, a flexible nitronate-bis(oxy)iminium ion (as an ion pair with triflate as counterion) equlibrium was found, and its thermodynamic parameters were determined. Elevation of temperature or dilution shifts this equilibrium toward the reactants. Activation parameters for the C,C-coupling reaction of silylated bis(oxy)iminium ions with a series of reference nucleophiles were determined. Estimated electrophilicity of bis(oxy)iminium ions allows one to count on C,C-coupling when partner nucleophilicity is N > 4.

Published 16 November 2007 in J Org Chem, 72(24): 9134-40.
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