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N -Alkyl- N -Cyclopropylanilines as Mechanistic Probes in the Nitrosation of N,N -Dialkyl Aromatic Amines

1999; American Chemical Society; Volume: 65; Issue: 1 Linguagem: Inglês

10.1021/jo991104z

1520-6904

Richard N. Loeppky, Saleh Elomari,

Synthesis and Catalytic Reactions

A group of N-cyclopropyl-N-alkylanilines has been synthesized, and their reaction with nitrous acid in aqueous acetic acid at 0 °C was examined. All compounds reacted rapidly to produce the corresponding N-alkyl-N-nitrosoaniline by specific cleavage of the cyclopropyl group from the nitrogen. The transformations were unaffected by the nature of the alkyl substituent (Me, Et, iPr, Bn). The reaction of 4-chloro-N-2-phenylcyclopropyl-N-methylaniline with nitrous acid gave 4-chloro-N-methyl-N-nitrosoaniline (76%), cinnamaldehyde (55%), 3-phenyl-5-hydroxyisoxazoline (26%), and 5-(N-4-chlorophenylmethylamino)-3-phenylisoxazoline (8%). Both the selective cleavage of the cyclopropyl group from the aromatic amine nitrogen and nature of the products derived from the cyclopropane ring support a mechanism involving the formation of an amine radical cation. This step is followed by rapid cyclopropyl ring opening to produce an iminium ion with a C-centered radical which either combines with NO or is oxidized.