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Updated: May 23, 2026

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Medium-sized rings versus macrocycles through rhodium-catalyzed ring-expansion reactions of cyclic acetals
Rafael Ballesteros-Garrido1, Diane Rix, Céline Besnard
1Département de Chimie Organique, Université de Genève, quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland.
Abstract:
α-Diazo β-ketoesters and diketones react with cyclic acetals under Rh(II) catalysis to yield unprecedented polyoxygenated 8- and 9-membered rings in one pot. The reactions occur under mild conditions with yields up to 90%. A perfect regioselectivity is obtained, which can be rationalized through a mechanistic hypothesis that considers 1) the formation of an oxonium ylide, 2) its transformation into an unsaturated acyclic oxocarbenium electrophilic intermediate, and 3) an intramolecular nucleophilic attack in a direct application of Baldwin's rules.
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