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Updated: Jul 14, 2026

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Asymmetric alpha-alkynylation of piperidine via N-sulfinyliminium salts
Serge Turcaud1, Emma Sierecki, Thierry Martens
1Synthèse et Structure de Molécules d'Intérêt Pharmacologique, UMR 8638 CNRS-Université Paris 5, 75270 Paris cedex 6, France.
Abstract:
Piperidine was stereoselectively alpha-alkynylated in a four-step sequence made up of transformation to a chiral nonracemic N-sulfinylpiperidine, anodic oxidation to N-sulfinyliminium ion equivalent, alkynylation through addition of a mixed organoaluminum derivative, and final acidic deprotection of the sulfoxide. Overall yields are around 50%, and the diastereoselectivity of the nucleophilc addition was between 92 and 99% de, allowing isolation of the final product with 99% enantiomeric purity.
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