TY  - JOUR
UR  - https://doi.org/10.1002/rcm.1290090716
N2  - The influence of cyclopentane fusion on the fragmentation behaviour of 1,3-oxazines and related thiazines was studied. The differences observed in the rearrangement reactions between the hydrogen atom at the ortho position of the aromatic ring and one of the hetero atoms in the cyclohexane ring were also investigated. These rearrangements occur if the cyclohexane ring contains an electrophilic atom and the carbon atom next to it is substituted by a benzyl or arylamino group. The compounds examined were cis and trans isomers of the title compounds substituted with methyl and benzyl (in the latter case only the cis isomers) on the ring nitrogen. All the compounds exhibited a large [M - H]+ ion peak which decreased with increasing size of the substituent. This indicates an intramolecular cyclization prior to further fragmentation of the molecule. Methyl substitution seems to change the character of this intramolecular cyclization. The main routes of fragmentation resemble those of the cyclohexane-fused analogues more than those of the corresponding 5,6-fused compounds. The stereoisomers fragment so similarly that they cannot be distinguished from each other, except in the case of methyl substituted oxazines.
AV  - restricted
SN  - 0951-4198
A1  -  Oksman Pentti
A1  -  Pihlaja Kalevi
A1  -  Fülöp Ferenc
A1  -  Bernáth Gábor
VL  - 9
JF  - RAPID COMMUNICATIONS IN MASS SPECTROMETRY
SP  - 615
ID  - publicatio32470
IS  - 7
EP  - 624
TI  - Fragmentation and intramolecular cyclization in cyclopentane?4,5?fused 2?N?phenyliminoperhydro?1,3?oxazines and related thiazines under electron impact ionization
Y1  - 1995///
ER  -