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

Abstract

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.