Reversal of Diastereoselectivities in Intra- and Intermolecular Reactions of 2-Adamantanylidenes Primarily Caused by Electron-Donating and Electron- Withdrawing Substituents on C5

A reversal of diastereoselectivity was observed for novel 5-(trimethylsilyl)adamantan-2-ylidene (1c) with regard to 5-hydroxyadamantan-2-ylidene (1a). Ostensibly in intermolecular reactions, 5-substituted 2-adamantanylidenes (1) are sterically unbiased. However, inductive effects originating from th...

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Bibliographic Details
Published in:Organic letters 2003-08, Vol.5 (16), p.2943-2946
Main Authors: Knoll, Wolfgang, Bobek, Michael M, Kalchhauser, Hermann, Rosenberg, Murray G, Brinker, Udo H
Format: Article
Language:English
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Summary:A reversal of diastereoselectivity was observed for novel 5-(trimethylsilyl)adamantan-2-ylidene (1c) with regard to 5-hydroxyadamantan-2-ylidene (1a). Ostensibly in intermolecular reactions, 5-substituted 2-adamantanylidenes (1) are sterically unbiased. However, inductive effects originating from the pendant group bend the divalent carbon bridge of 1 either toward (ERG's, e.g., −Si(CH3)3) or away from (EWG's, e.g., −OH) the γ-position. Hence, the more exposed side is more susceptible to intermolecular reaction and the other side concomitantly undergoes intramolecular 1,3-CH insertions more readily.
ISSN:1523-7060
1523-7052
DOI:10.1021/ol0350700