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Updated: Jul 19, 2026

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Stereoselective synthesis of 2,4,5-trisubstituted tetrahydropyrans using an intramolecular allylation strategy
Peter J Jervis1, Benson M Kariuki, Liam R Cox
1School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Abstract:
A highly stereoselective route to 2,4,5-trisubstituted tetrahydropyrans is reported. The key step employs an intramolecular allylation of a (Z)-allylsilane onto an aldehyde under Brønsted acid activation. Complete 1,4-stereoinduction accounts for the formation of only two out of the possible four THP products. The level of 1,3-stereoinduction is optimal when the reaction is carried out in an apolar solvent, which is in accord with electrostatics being key to controlling this aspect of the stereoselectivity.
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