Base-promoted elimination reactions of (E)- and (Z)-arylaldehyde O-benzoyloximes. Effects of stereochemistry, β-aryl group, and base-solvent on the nitrile-forming transition states
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چکیده
This account summarizes the results of mechanism studies on the nitrile-forming eliminations from (E)and (Z)-arylaldehyde O-benzoyloximes promoted by 1,8-diazabicyclo-[5.4.0]undec-7ene (DBU) in MeCN, R1R2NH in MeCN, and R1R2NH/R1R2NH2 in 70mol% MeCN(aq). The rate of anti-elimination was 36,000-fold faster than that of syn-elimination. The change of the βaryl group from Ph to thienyl to furyl shifted the E2 transition state slightly towards product-like. When (E)-2,4-dinitrobenzaldehyde O-benzoyloxime was employed as the reactant and R1R2NH/R1R2NH2 in 70mol% MeCN(aq) was used as the base-solvent, the (E1cb)irr was observed.
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تاریخ انتشار 2010