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Updated: Jun 9, 2026

Characterizing Lewis Pairs Using Titration Coupled with In Situ Infrared Spectroscopy
Published on: February 20, 2020
Stereochemical surprises in the Lewis acid-mediated allylation of isatins
Devendra J Vyas1, Roland Fröhlich, Martin Oestreich
1Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, 48149 Münster, Germany.
Abstract:
The BF(3)·OEt(2)-mediated allylation of isatin with an α-chiral allylic stannane is diastereo- and enantioselective. Conversely, allylation of any substituted isatin employing the identical protocol is not diastereoselective at all and only enantioselective for the major diastereomer having syn relative configuration. The anti isomer is, however, formed in almost racemic form. Both absolute and relative configurations are unambiguously secured by X-ray analysis of major isomers, and the stereochemical assignment of the other 3-substituted 3-hydroxy oxindoles is based on similar NMR spectroscopic characteristics. The remarkable observations are rationalized by an acyclic transition state model.
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