REACTIONS OF THE NITROSONIUM ION .11. FLUORIDE TRANSFER FROM COMPLEX FLUORIDE ANIONS TO CARBENIUM IONS IN THE NITROSATIVE DECOMPOSITION OF ALIPHATIC AZIDES

Results from nitrosative reactions of aliphatic azides, azido nitriles, and phenoxy azides with nitrosonium salts in chloroform are reported. The presence of the basic nitrile or ether functional group causes a significant increase in the yield of fluoroalkane products, from 5% with 1-azidohexane to 50-81% in reactions with azido nitriles. Elimination reactions and protonic decomposition (Curtius rearrangement), which are major competing processes in the nitrosative decomposition of aliphatic azides, are minimized or not observed in nitrosative reactions with azido nitriles and phenoxy azides. Fluoride transfer is even competitive with intramolecular Friedel-Crafts alkylation from nitrosative reactions of phenoxy azides, but nitrosative decomposition of benzyl 5-azidopentanoate results in the exclusive formation of lactones. Enhancement of fluoride substitution is explained by intimate association of the basic functional group at the surface of the nitrosonium salt causing nitrosative decomposition of the azide to occur in close proximity to the complex fluoride anion. © 1979, American Chemical Society. All rights reserved.