title: Reversal of diastereoselectivities in intra- and intermolecular reactions of 2-adamantanylidenes primarily caused by electron-donating and electron- withdrawing substituents on C5.
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.
authors.affiliation: Institut für Organische Chemie, Universität Wien, Währinger Strasse 38, A-1090 Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Knoll
authors.forename: Michael M
authors.initials: MM
authors.lastname: Bobek
authors.forename: Hermann
authors.initials: H
authors.lastname: Kalchhauser
authors.forename: Murray G
authors.initials: MG
authors.lastname: Rosenberg
authors.forename: Udo H
authors.initials: UH
authors.lastname: Brinker