BrF₃, an underutilized reagent in organic chemistry: A novel C-C-N to C-N-C rearrangement

Little is known about bromine trifluoride in organic chemistry. Under the right conditions, it can be a useful tool and generate a new and unprecedented chemistry. Thus, when reacted with oxime methyl ethers of α-ketoesters, BrF₃ was able to convert the oxime group into a CF₂ group and through a new type of rearrangement cause a shift of the carboxylate group to the nitrogen atom. The novel structure of the α,α-difluorocarbamate was also proven by ¹⁵N NMR as demonstrated for compounds 3, 8, 9, 12, 15, and 18. Another novel "double rearrangement" was observed during the formation of 19. Dynamic ¹⁹F NMR experiments indicate a high nitrogen inversion-rotation (NIR) barrier for these novel carbamates of about 12.5 kcal/mol.