title: Control of the ambident reactivity of the nitrite ion.
abstract: In previous studies, it was reported that a neighbouring equatorial ester group is essential for a good yield of nitrite-mediated triflate inversion, whereas with neighbouring benzyl ether groups or axial ester groups, mixtures are generally produced. In the present study, the origin of this difference was addressed. The ambident reactivity of the nitrite ion has been found to be the cause of the complex product formation observed, which can be controlled by a neighbouring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favoured in its presence. A neighbouring group assistance mechanism is proposed, in addition to steric effects, based on secondary interactions between the neighbouring ester group and the incoming nucleophile. High-level quantum mechanical calculations were carried out in order to delineate this effect. The theoretical results are in excellent agreement with experiments, and suggest a catalytic role for the neighbouring equatorial ester group.
authors.affiliation: Huazhong University of Science and Technology, School of Chemistry and Chemical Engineering, Luoyu Rd 1037, 430074, Wuhan, PR China. hdong@mail.hust.edu.cn
authors.forename: Hai
authors.initials: H
authors.lastname: Dong
authors.forename: Martin
authors.initials: M
authors.lastname: Rahm
authors.forename: Niranjan
authors.initials: N
authors.lastname: Thota
authors.forename: Lingquan
authors.initials: L
authors.lastname: Deng
authors.forename: Tore
authors.initials: T
authors.lastname: Brinck
authors.forename: Olof
authors.initials: O
authors.lastname: Ramström