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 alpha-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 alpha,alpha-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.
Rozen
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School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel. rozens@post.tau.ac.il
Ben-David
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