124418-03-7Relevant articles and documents
Rearrangement of chiral 1-bromo-N-nitrobicyclo[2.2.1]heptan-2-imines
Grytsai, Oleksandr V.,Gorichko, Marian V.,Golovko, Vladimir B.
, p. 817 - 821 (2013)
The regio- and diastereospecific Wagner-Meerwein-type rearrangements of the potassium cyanide adducts of camphor-derived substituted 1-bromo-N- nitrobicyclo[2.2.1]heptan-2-imines under acidic conditions have been investigated. The selective formation of bromonorbornene derivatives has been demonstrated in the case of rearrangements involving intermediate α-bromocarbocations containing vicinal hydrogen atoms. In all other cases, hydrolysis of the intermediates resulted in the formation of a carbonyl group. The simplicity of this transformation opens up a novel and straightforward synthetic pathway to enantiopure derivatives of bridgehead-substituted norbornane carboxamides in just three steps, starting from 1-bromonorbornanones.
Boat/chair topographic stereoselection during anionic oxy-cope rearrangement of 1-alkenyl-2-cyclopentenyl-endo-norbornan-2-ols
Paquette, Leo A.,Teleha, Christopher A.,Taylor, Richard T.,Maynard, George D.,Rogers, Robin D.,Gallucci, Judith C.,Springer, James P.
, p. 265 - 277 (2007/10/02)
In to examine which of four possible [3,3] sigmatropic transition states 1-alkenyl-2-cyclopentenyl-enyl-endonorbornan-2-ols would adopt during oxy-Cope rearrangement of their potassium salts at room temperature, the functionalized norbornanones 15, 19, 20, and 24-26 were prepared. Since those in the 3,3-dimethyl series are derived from (1 R)-(-)-fenchone, they were available in optically pure form. Condensation of these ketones with cyclopentenyllithium (for the nonenolizable series) or cyclopentenyldichlorocerium(III) proceeded exclusively with C-C bond formation from the exo direction. In each example, oxy-Cope rearrangement took place efficiently, and structural assignments to the products were arrived at on the strength of extensive X-ray crystallographic data. In all but one instance, bridgehead olefinic ketones were formed. The major exception materialized because of unusual SN′ displacement of methoxide ion by the transannularly positioned enolate ion. The stereochemistries of these products are inextricably linked to the particular operational transition state. The results show clearly that exo-boat transition states are utilized as long as the sigmatropic change occurs readily, as it does except in one example. A slower reaction rate favors adoption of an exo-chair geometry. From the synthetic viewpoint, the stereochemical control elements elucidated herein point the way to the possible utilization of this methodology in elaboration of diverse oxacembranolides.
