Control of the ambident reactivity of the nitrite ion.

Artikel i vetenskaplig tidskrift, 2013

In previous studies, it was reported that a neighboring equatorial ester group is essential for a good yield of nitrite-mediated triflate inversion, whereas with neighboring benzyl ether groups or axial ester groups, mixts. are generally produced. The origin of this difference was addressed. The ambident reactivity of the nitrite ion is the cause of the complex product formation obsd., which can be controlled by a neighboring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favored in its presence. A neighboring group assistance mechanism is proposed, in addn. to steric effects, based on secondary interactions between the neighboring ester group and the incoming nucleophile. High-level quantum mech. calcns. were carried out to delineate this effect. The theor. results are in excellent agreement with expts., and suggest a catalytic role for the neighboring equatorial ester group. [on SciFinder(R)]