Can Acyl Transfer Occur by a Concerted Mechanism? Direct Evidence from Heavy-Atom Isotope Effects

Authors

Alvan C. Hengge, Utah State UniversityFollow

Document Type

Article

Journal/Book Title

Journal of the American Chemical Society

Publication Date

1992

Volume

114

First Page

6575

Last Page

6576

Abstract

Nucleophilic acyl-transfer reactions most often occur by way of a two-step mechanism with a tetrahedral intermediate, described in the IUPAC system¹ as A_N + D_N. Acyl halides can react through an acylium ion intermediate by an S_N1 (D_N + A_N) mechanism.² There has been interest in the question of whether ester acyl transfers can proceed by a concerted S_N2 (A_ND_N) pathway.³ On the basis of structure-reactivity studies, Williams et al. proposed that the reaction of phenoxide anions with p-nitrophenyl acetate proceeds by such a concerted pathway,^4a and they proposed a theory predicting when ester acyl transfers will be concerted and when they will go by the limiting stepwise mechanisms.⁵ These conclusions have been challenged.⁶ Recently, theoretical arguments have been presented in support of a concerted mechanism in reactions of aryl acetates with phenoxide anions.⁷

Recommended Citation

A. C. Hengge. “Can Acyl Transfer Occur by a Concerted Mechanism? Direct Evidence from Heavy Atom Isotope Effects.” J. Am. Chem. Soc.1992, 114, 6575-6576.