N-Alkyl-N-cyclopropylanilines as mechanistic probes in the nitrosation of N,N-dialkyl aromatic amines.
A group of N-cyclopropyl-N-alkylanilines has been synthesized, and their reaction with nitrous acid in aqueous acetic acid at 0 degrees 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, (i)()Pr, 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.
Loeppky
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Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA. LoeppkyR@missouri.edu
Elomari
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S
D000588:Amines / Q000737:chemistry*; D000814:Aniline Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015335:Molecular Probes; D009603:Nitroso Compounds / Q000737:chemistry*
D000588:Amines; D000814:Aniline Compounds; D015335:Molecular Probes; D009603:Nitroso Compounds; C023650:aniline