The electron ionization (EI) and collision-induced dissociation (CID) spect
ra of substituted N-(ortho-cyclopropylphenyl)benzamides 1-7 and N-[ortho-(1
-methylcyclopropyl)phenyl]benzamides 8-12 Were recorded. In addition to rou
tine bond cleavages, the molecular ions (M+) of 1-12 undergo cyclization in
to the corresponding 3-aryl-1-alkyl-1-ethyl-1H-benzoxazines and isomeric 5-
ethyl-2-oxodibenzoazepines. The presence of a methyl group in the cycloprop
yl ring (compounds 8-12) makes the formation of 5-ethyl-2-oxodibenzoazepine
less favorable. In accord with mass spectrometric predictions, compound 13
(3-p-tolyl-1-ethyl-1H-benzoxazine) was obtained as a major product of the
reaction of N-(ortho-cyclopropylphenyl)-4-methylbenzamide 1 with sulfuric a
cid. Traces of 5-ethyl-2-oxodibenzoazepine were also detected in gas chroma
tography-mass spectrometry (GC-MS) analysis of the reaction mixture althoug
h the yield was too low to allow its isolation. (C) 2001 American Society f
or Mass Spectrometry.