Reversal of diastereoselectivities in intra- and intermolecular reactions of 2-adamantanylidenes primarily caused by electron-donating and electron- withdrawing substituents on C5

Wolfgang Knoll; Michael M Bobek; Hermann Kalchhauser; Murray G Rosenberg; Udo H Brinker

doi:10.1021/ol0350700

Reversal of diastereoselectivities in intra- and intermolecular reactions of 2-adamantanylidenes primarily caused by electron-donating and electron- withdrawing substituents on C5

Org Lett. 2003 Aug 7;5(16):2943-6. doi: 10.1021/ol0350700.

Authors

Wolfgang Knoll¹, Michael M Bobek, Hermann Kalchhauser, Murray G Rosenberg, Udo H Brinker

Affiliation

¹ Institut für Organische Chemie, Universität Wien, Währinger Strasse 38, A-1090 Vienna, Austria.

PMID: 12889914
DOI: 10.1021/ol0350700

Abstract

[reaction: see text] 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(CH(3))(3)) or away from (EWG's, e.g., -OH) the gamma-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.