Camphorae: chiral intermediates fob the total synthesis of steroids

Recyclization reactions of 8,10-dibromocamphor with Grignard and organolithium compounds

Grignard reagents and organolithium compounds react with 8,10-dibromocamphor to afford substituted 1-methyl-2-methylenebicyclo[3.2.0]heptanes. Recyclization proceeds via intramolecular enolate alkylation and Grob fragmentation of the reaction intermediates. All compounds have been characterized by 1H, 13C and 19F NMR spectroscopy and their chemical composition proved by HRMS analyses. The relative spatial arrangement of substituents in the molecule of (1-methyl-2-methylenebicyclo[3.2.0]heptan-6-yl)diphenylmethanol was studied by NOESY experiments.

Beckmann Rearrangement of 3-carboxybicyclo[3.3.1]nonane and [3.2.1]octane Oximes

Regiospecific Beckmann rearrangement of substituted 2-hydroximinonorbornanone carboxylic acids has been investigated. Selective formation of new functionalized 10-oxo-9-azabicyclo[3.3.2]decanes and 7-oxo-6-azabicyclo[3.2.2]nonanes in good yield has been demonstrated. Presence of neighboring carboxylic group allows conducting of Beckmann rearrangement of strained bicyclic compounds.

Enantiospecific access to various C(9),C(10)-disubstituted camphors: scope and limitations

The valuable chiral sources C(9),C(10)-disubstituted camphors can be enantiospecifically obtained from the corresponding C(9)-substituted camphors by a general and straightforward synthetic method. This method involves the electrophilic treatment of a key 2-methylenenorbornan-1-ol intermediate, followed by a controlled tandem carbon-carbon double-bond addition-Wagner-Meerwein rearrangement of the norbornane framework. Discussion of the results presented suggests possible extensions and limitations of the methodology used. The feasibility of this method has been exemplified by the highly efficient enantiospecific preparation of several interesting C(9)-halogen-, C(10)-halogen, O-, S-, or Se-substituted camphors.